Enormous Sunspot 1944 Unleashes X-Class Flare! (January 8, 2014)
More flares are in the offing. The sunspot has an unstable 'beta-gamma-delta' magnetic field that is likely to erupt again today. NOAA forecasters estimate an 80% chance of M-class flares and a 50% chance of X-flares on Jan. 8th.
Christmas Aurora a Surprising Present for Some Observers (December 27, 2013)
While sunspots 1934 and 1936 continue to maintain high levels of magnetic instability and should be monitored closely, forecasters have lowered expectations for any significant eruptive activity over the next 24-48 hours. Christmas Lights Turned On! Skies above the Arctic Circle turned green on Dec. 25th when the interplanetary magnetic (IMF) field near Earth turned south. This opened a crack in our planet's magnetosphere. Solar wind poured in and fueled a display of Northern Lights: 
"I saw these at 8:30 am on Dec. 25th," says photographer John Dean of Nome, Alaska. "They were the first Christmas auroras I have ever seen."
The day after Christmas could be good, too. A solar wind stream is expected to brush past Earth's magnetic field on Dec. 26th, prompting NOAA to estimate a 35% chance of polar geomagnetic storms. High-latitude sky watchers should remain alert for auroras. Flare Activity Picking Up, Chance for Radiation Storm (December 23, 2013)
The eruption of an M3.3 class flare from sunspot region 1928 which initiated at 15:12UTC on Sunday captured in extreme ultraviolet light by SDO/EVEcameras.
Big sunspot 1928 has been acting up over the last 24 hours, popping and churning with flare activity. Three moderate M-class x-ray flares erupted on Sunday from this region (see image of one of them above). Magnetic fields spiraling away from the sunspot's location near the sun's western limb are well-connected to Earth, raising the possibility of a radiation storm around our planet if the flares intensify.
The image below is an updated look at 13:00 UTC showing visible sunspots currently located in the southeast quadrant, along with sunspot 1928 (inset) approaching the west limb. In addition to the eruptions around sunspot 1928, sunspot 1934 has also been active, generating an m1.6 class flare itself on Sunday. As well, a yet to be numbered region now in view near the southeast limb has also erupted in the last 24 hours. Currently, solar activity is fairly stable since the M1.6 flare around 1928 at 09:06 UTC this morning, however there will remain a chance for C-Class flares, and perhaps another isolated M-Class event. Solar wind conditions have been nominal and the geomagnetic field has been relatively quiet. 
C9 Class Flare Highlights a Relatively Quiet Day on the Sun (December 22, 2013)
The slight decline in solar activity that occurred yesterday has leveled off at a relatively low intensity of flare activity. Region 1928 (beta-gamma magnetic field potential) produced several C-class flares during the period including a C9-class flare at 21/1036 UTC and a C7 flare at 21/1929 UTC. Regions 1928 and 1934 continued to show slight growth in intermediate and trailing spots during the period. No Earth-directed coronal mass ejections were observed during the period. NOAA forecasters are calling for solar activity to continue to be low with a 40% chance for M-class flare activity and only a slight chance for X-class flare activity for the next three days (22-24 Dec), with regions 1928 or 1934 being the likely source. Meanwhile, the earth's magnetic field has been relatively quiet and is expected to remain so over the next 24 hours as both the solar wind and interplanetary magnetic field show no signs of changing from their current nominal levels.
The zone around sunspot 1928 is one of the most intense regions of built-up magnetic strain on the earth-facing side of the sun. Any moderate-strength x-ray flare activity is likely to come from this zone or from sunspot 1934. (SDO)
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STEREO-B is located on the far side of the sun where it can look back and see Earth along with other planets in the Solar System. From STEREO-B's point of view, Earth and Jupiter are so close together that the spacecraft's Heliospheric Imager can barely tell the two apart. Venus is only 2 degrees from the Earth-Jupiter pair, so this is actually a 3-way conjunction.
This meeting is not nearly as tight as the putative Star of Bethlehem conjunction ~2000 years ago. At that time Venus and Jupiter could have been as little as 6 arcseconds (0.00166 degrees) apart. Nevertheless, the ongoing display is still special because it's the first "Christmas Star conjunction" from space. Happy Holidays from STEREO! Ursid Meteor Shower Peaks Today
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Low Intensity C-Class Flares Only Action of Note on Solar Disk (December 19. 2013)
Solar activity remains at low levels with only a sputtering of minor x-ray flares occurring in the past 24 hours. Region 1930 was the most active spot group, producing three C-class flares during the period. Each event was C1 in magnitude with the flare at 19/0719 UTC having a subfaint optical correlation. This region continues to be in a growth phase, showing separation between the leader and trailer spots, as well as development in the intermediate spots. Region 1928 (with a Beta-Gamma magnetic configuration) also continued to develop, showing consolidation in the leading spots, consolidation in the intermediate spots, yet overall separation between the leader and trailer spots. This region also produced a C1-class flare at 19/0918 UTC. The other regions on the visible disk were either stable or exhibited signs of decay. No Earth-directed coronal mass ejections were detected in satellite imagery throughout the period. The NOAA solar forecast calls for solar activity to continue to be low in intensity with a 30% chance for M-class (Minor-Moderate) flare activity for the next three days. All other regions, including newly numbered 1931, remain stable. Existing region 1917 is now rotating onto the west limb.
Lots of Little Sunspots, But Sun Grows Quiet (December 17, 2013)
Newly formed sunspot region 1928 is growing quickly today in the southeast quadrant of the solar disk and has alreadly developed a fairly strong Beta-Gamma magnetic field potential.
Solar activity this morning was at very low levels over the last 24 hours. All visible regions, including sunspot 1917 are currently stable. Sunspot 1927 is about to rotate onto the west limb and out of direct Earth view. New sunspot 1928 was numbered overnight after quickly forming in the southeast quadrant. It has exhibited fairly rapid growth throughout the last 24 hours, while displaying prominent mixing within its magnetic structure. It is currently exhibiting a beta/gamma magnetic field potential, indicating an increased possibility for fairly strong solar flare activity in the near future. However, for now forecasters are only willing to predict that there will remain a chance for at least C-Class solar flares somewhere on the solar disk in the next 24 hours. Old region 1913 will begin to rotate back into view off the east limb during the next 24-36 hours.
Solar Flares Low in Intensity, But Sun Still Churns Away (December 16, 2013)
Image of the lower quieter regions of the Sun's corona and upper transition zone late this afternoon taken with the Solar Dynamics Observatory cameras using the AIA 171 filter.
Solar flare activity has remained low in intensity over the last 24 hours. Sunspot 1917 remained the most active visible region, producing a couple of minor C-Class solar flares. This region along with sunspot 1918, have 'beta-gamma' magnetic fields that harbor energy for moderately strong solar flares. Any eruptions from the duo in the days ahead would likely be geoeffective. NOAA forecasters estimate a 25% chance of M-class flares during the next 24 hours. All other numbered regions remained stable. New sunspot 1927 formed quickly in the southwest quadrant, but will soon begin to rotate onto the west limb. Old active region 1913 from the previous rotation is now just over a day away from returning back into view off the east limb. This is the active region responsible for an onslaught of almost continuous plasma eruptions beyond the solar limb on Saturday. There will remain a chance for at least C-Class solar flares during the next 24 hours. NOAA forecasters are expecting the Earth's magnetic field to remain relatively quiet for the upcoming 24 hours.
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Leviathan's Lunar Feature of the Week #5: Cauchy: An Intriguing Volcanically and Geologically Active Region
Article by Peter Grego
Across the north-eastern plains of the Sea of Tranquiility, more than 500 km from the Apolio 11 landing site, lie two magnificent near-parallel cracks in the Moon's surface, both more than 200 km long. Rupes and Rima Cauchy (the Cauchy scarp and rille) are named after the bright 12 km diameter impact crater Cauchy that lies between them. Both features were formed after the massive lava flows that formed the sea had cooled and had begun to settle, and they were caused by a localised stretching apart of the lunar crust. Cauchy crater itself is a small lunar impact crater, circular and symmetric, with a small interior floor at the midpoint of the sloping inner walls. It has been measured to have a depthof 2.6 km from the top of the crater rim down to its floor. Due to the high albedo of this bowl-shaped formation, it is particularly prominent at full Moon.
Like the crust of the Earth, the Moon's crust is capable of being deformed by stresses. In some lunar seas there are examples of wrinkle features that have arisen as a result of the Moon's crust buckling under pressure. But beyond a critical degree of compression or tension the rocks suddenly fault, giving rise to fault scarps, ridges and rilles. Some faults can be very deep-seated, like the so-called Straight Wall (Rupes Recta) in Mare Nubium which undoubtedly cuts through the upper lava strata into the very bedrock of the Nubian basin.
Like the crust of the Earth, the Moon's crust is capable of being deformed by stresses. In some lunar seas there are examples of wrinkle features that have arisen as a result of the Moon's crust buckling under pressure. But beyond a critical degree of compression or tension the rocks suddenly fault, giving rise to fault scarps, ridges and rilles. Some faults can be very deep-seated, like the so-called Straight Wall (Rupes Recta) in Mare Nubium which undoubtedly cuts through the upper lava strata into the very bedrock of the Nubian basin.
Thrust faults occur when the lunar crust is compressed laterally, breaking the rocky materials below and forming a long scarp (rupes) on the surface.
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Graben are troughs formed when the lunar crust was stretched and pulled apart. This stretching causes the near-surface materials to break along two parallel normal faults, the terrain in between the twin faults drops down forming a valley (rima).
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Rupes Cauchy is part rille, part escarpment, and appears a little more complicated than the clean scarp of Rupes Recta or the chisel-cut rille of the Rima Cauchy. Rupes Cauchy begins in the west at a pair of tiny oval craterlets (visible in a 150 mm reflector or larger) and several larger craters lie just along its length. Rupes Cauchy extends eastward to meet with the ragged mountain border of Mare Tranquillitatis, and there is evidence that it cuts through the mountains to meet with the small ruined crater Lawrence. What is to be made of the craters that lie along the Rupes Cauchy? Many of the Moon's rilles appear to be composed (at least in part) by elongated craterlets or chains of craters. In some cases the original faulting may have instigated fresh bouts of volcanic activity that produced small volcanic vents along the fissure. There certainly has been a good deal of volcanic activity in this region, for just to the south of Rupes Cauchy lie two beautiful volcanic domes (squat volcanoes) designated Tau and Omega, the latter sporting a small summit craterlet. A number of other more subtle dome features may be found in the area, but require good seeing conditions to be detectable. The best time to view any of these domes is around lunar local sunrise or sunset, when the low angle sunlight provides better contrast effects against the surrounding terrain. For these features, this occurs on day 4/5 and again at day 18/19 after new moon.
The low angle sunlight provided when this region is near local lunar sunrise or sunset gives the volcanic dome features enough contrast to make them visible through a small telescope at moderately high power. Click to enlarge. Image by Avani Soares.
The crater Cauchy is easily visible in a pair of binoculars as a bright spot at high illuminations. Rupes and Rima Cauchy, along with the two nearby domes, are all visible in a 60 mm refractor when they are positioned close to the terminator at low angles of illumination. At lunar sunrise Rupes Cauchy (like Rupes Recta) casts a dark shadow onto the plain to the east. At sunset the feature appears as a bright line, its western scarp face being brightly illuminated. In order to see the summit craterlet on Omega you will require at least a 150 mm reflector at high magnification under good seeing conditions.
Towards the lower corner of the yellow square in this image lies a very geologically diverse (and at one time, active) part of the Sea of Tranquility - the Cauchy Region. In it you will find volcanic domes, craters of all shapes and sizes and at least two spectacular fault features: Rima and Rupes Cauchy. Image by Vaz Tolentino.
The new study finds that the supernovae are likely powered by the creation of a magnetar, an extraordinarily magnetized neutron star spinning hundreds of times per second. Magnetars have the mass of the sun packed into a star the size of a city and have magnetic fields a hundred trillion times that of Earth. While a handful of these superluminous supernovae have been seen since they were first announced in 2009, and the creation of a magnetar had been postulated as a possible energy source, the work of Howell and his colleagues is the first to match detailed observations to models of what such an explosion might look like.
Co-author Daniel Kasen from UC Berkeley and Lawrence Berkeley National Lab created models of the supernova that explained the data as the explosion of a star only a few times the size of the sun and rich in carbon and oxygen. The star likely was initially much bigger but apparently shed its outer layers long before exploding, leaving only a smallish, naked core.
"What may have made this star special was an extremely rapid rotation," Kasen said. "When it ultimately died, the collapsing core could have spun up a magnetar like a giant top. That enormous spin energy would then be unleashed in a magnetic fury."
Discovered as part of the SNLS -- a five-year program based on observations at the Canada-France-Hawaii Telescope, the Very Large Telescope (VLT) and the Gemini and Keck telescopes to study thousands of supernovae -- the two supernovae could not initially be properly identified nor could their exact locations be determined. It took subsequent observations of the faint host galaxy with the VLT in Chile for astronomers to determine the distance and energy of the explosions. Years of subsequent theoretical work were required to figure out how such an astounding energy could be produced.
The supernovae are so far away that the ultraviolet (UV) light emitted in the explosion was stretched out by the expansion of the universe until it was redshifted (increased in wavelength) into the part of the spectrum our eyes and telescopes on Earth can see. This explains why the astronomers were initially baffled by the observations; they had never seen a supernova so far into the UV before. This gave them a rare glimpse into the inner workings of these supernovae. Superluminous supernovae are so hot that the peak of their light output is in the UV part of the spectrum. But because UV light is blocked by Earth's atmosphere, it had never been fully observed before.
The supernovae exploded when the universe was only 4 billion years old. "This happened before the sun even existed," Howell explained. "There was another star here that died and whose gas cloud formed the sun and Earth. Life evolved, the dinosaurs evolved and humans evolved and invented telescopes, which we were lucky to be pointing in the right place when the photons hit Earth after their 10-billion-year journey."
Such superluminous supernovae are rare, occurring perhaps once for every 10,000 normal supernovae. They seem to explode preferentially in more primitive galaxies -- those with smaller quantities of elements heavier than hydrogen or helium -- which were more common in the early universe.
"These are the dinosaurs of supernovae," Howell said. "They are all but extinct today, but they were more common in the early universe. Luckily we can use our telescopes to look back in time and study their fossil light. We hope to find many more of these kinds of supernovae with ongoing and future surveys."
Co-author Daniel Kasen from UC Berkeley and Lawrence Berkeley National Lab created models of the supernova that explained the data as the explosion of a star only a few times the size of the sun and rich in carbon and oxygen. The star likely was initially much bigger but apparently shed its outer layers long before exploding, leaving only a smallish, naked core.
"What may have made this star special was an extremely rapid rotation," Kasen said. "When it ultimately died, the collapsing core could have spun up a magnetar like a giant top. That enormous spin energy would then be unleashed in a magnetic fury."
Discovered as part of the SNLS -- a five-year program based on observations at the Canada-France-Hawaii Telescope, the Very Large Telescope (VLT) and the Gemini and Keck telescopes to study thousands of supernovae -- the two supernovae could not initially be properly identified nor could their exact locations be determined. It took subsequent observations of the faint host galaxy with the VLT in Chile for astronomers to determine the distance and energy of the explosions. Years of subsequent theoretical work were required to figure out how such an astounding energy could be produced.
The supernovae are so far away that the ultraviolet (UV) light emitted in the explosion was stretched out by the expansion of the universe until it was redshifted (increased in wavelength) into the part of the spectrum our eyes and telescopes on Earth can see. This explains why the astronomers were initially baffled by the observations; they had never seen a supernova so far into the UV before. This gave them a rare glimpse into the inner workings of these supernovae. Superluminous supernovae are so hot that the peak of their light output is in the UV part of the spectrum. But because UV light is blocked by Earth's atmosphere, it had never been fully observed before.
The supernovae exploded when the universe was only 4 billion years old. "This happened before the sun even existed," Howell explained. "There was another star here that died and whose gas cloud formed the sun and Earth. Life evolved, the dinosaurs evolved and humans evolved and invented telescopes, which we were lucky to be pointing in the right place when the photons hit Earth after their 10-billion-year journey."
Such superluminous supernovae are rare, occurring perhaps once for every 10,000 normal supernovae. They seem to explode preferentially in more primitive galaxies -- those with smaller quantities of elements heavier than hydrogen or helium -- which were more common in the early universe.
"These are the dinosaurs of supernovae," Howell said. "They are all but extinct today, but they were more common in the early universe. Luckily we can use our telescopes to look back in time and study their fossil light. We hope to find many more of these kinds of supernovae with ongoing and future surveys."
Comet Lovejoy's Long Tail Likely To Grow as Comet Reaches Perihelion
(December 18, 2013)
Next week, Comet Lovejoy makes its closest approach to the sun. The comet's tail is already amazing. Scroll down this image taken by Gerald Rhemann of Jauerling, Austria, for more information:
Filled with knots and eddies of dusty plasma, Lovejoy's tails stretches more than 20 degrees across the sky--long enough to overlap 40 full Moons or fill the Bowl of the Big Dipper twice. At closest approach to the sun or "perihelion" on Dec. 23rd, the comet will be just inside the orbit of Earth (0.82 AU). The extra heating it gets at perihelion will grow the tail even more.
Comet Lovejoy shines like a 4th magnitude star so it is barely visible to the unaided eye (especialy when the sky is filled with full moonlight). However, for backyard telescopes, the comet is a fairly easy target rising ahead of the sun in the eastern morning sky. If you have a GOTO telescope, send it to these coordinates. Slight pointing errors are no problem, because the tail is almost too broad to miss. Sky maps: Dec. 18, 19, 20.
Comet Lovejoy shines like a 4th magnitude star so it is barely visible to the unaided eye (especialy when the sky is filled with full moonlight). However, for backyard telescopes, the comet is a fairly easy target rising ahead of the sun in the eastern morning sky. If you have a GOTO telescope, send it to these coordinates. Slight pointing errors are no problem, because the tail is almost too broad to miss. Sky maps: Dec. 18, 19, 20.
Cepheid Variable RS Puppis Blasts Out Waves of Light (December 17, 2013)
by Jason Major, www.universetoday.com
6,500 light-years away in the southern constellation Puppis an enormous star pulses with light and energy, going through the first throes of its death spasms as it depletes its last reserves of hydrogen necessary to maintain a stable, steady radiance. This star, a Cepheid variable named RS Puppis, brightens and dims over a 40-day-long cycle, and newly-released observations with Hubble reveal not only the star but also the echoes of its bright surges as they reflect off the dusty nebula surrounding it.
The image above shows RS Puppis shining brilliantly at the center of its dusty cocoon. (Click the image for a super high-res version.) But wait, there’s more: a video has been made of the variable star’s outbursts as well, and it’s simply mesmerizing. Check it out below:
The image above shows RS Puppis shining brilliantly at the center of its dusty cocoon. (Click the image for a super high-res version.) But wait, there’s more: a video has been made of the variable star’s outbursts as well, and it’s simply mesmerizing. Check it out below:
Assembled from observations made over the course of five weeks in 2010, the video shows RS Puppis pulsing with light, outbursts that are then reflected off the structure of its surrounding nebula. What look like expanding waves of gas are really “light echoes,” radiation striking the densest rings of reflective dust located at farther and farther distances from the star.
According to the NASA image description:RS Puppis rhythmically brightens and dims over a six-week cycle. It is one of the most luminous in the class of so-called Cepheid variable stars. Its average intrinsic brightness is 15,000 times greater than our sun’s luminosity.
The nebula flickers in brightness as pulses of light from the Cepheid propagate outwards. Hubble took a series of photos of light flashes rippling across the nebula in a phenomenon known as a “light echo.” Even though light travels through space fast enough to span the gap between Earth and the moon in a little over a second, the nebula is so large that reflected light can actually be photographed traversing the nebula. (Source)
RS Puppis is ten times more massive than our Sun, and 200 times larger.
Cepheid variables are more than just fascinating cosmic objects. Their uncanny regularity in brightness allows astronomers to use them as standard candles for measuring distances within our galaxy as well as others — which is trickier than it sounds. Because of its predictable variation along with the echoing light from its surrounding nebula, the distance to RS Puppis (6,500 ly +/- 90) has been able to be calculated pretty accurately, making it an important calibration tool for other such stars. (Read more here.)
According to the NASA image description:RS Puppis rhythmically brightens and dims over a six-week cycle. It is one of the most luminous in the class of so-called Cepheid variable stars. Its average intrinsic brightness is 15,000 times greater than our sun’s luminosity.
The nebula flickers in brightness as pulses of light from the Cepheid propagate outwards. Hubble took a series of photos of light flashes rippling across the nebula in a phenomenon known as a “light echo.” Even though light travels through space fast enough to span the gap between Earth and the moon in a little over a second, the nebula is so large that reflected light can actually be photographed traversing the nebula. (Source)
RS Puppis is ten times more massive than our Sun, and 200 times larger.
Cepheid variables are more than just fascinating cosmic objects. Their uncanny regularity in brightness allows astronomers to use them as standard candles for measuring distances within our galaxy as well as others — which is trickier than it sounds. Because of its predictable variation along with the echoing light from its surrounding nebula, the distance to RS Puppis (6,500 ly +/- 90) has been able to be calculated pretty accurately, making it an important calibration tool for other such stars. (Read more here.)
New Lunar Crater Spotted
(December 17, 2013)
Most craters on the Moon were formed millions or even billions of years ago. NASA's Lunar Reconnaissance Orbiter just found one, however, that is only 9 months old. On March 17, 2013, a bright flash of light emerged from Mare Imbrium, the Sea of Rains. Researchers concluded that a small asteroid about 0.4 meters wide hit the lunar surface and exploded like 5 tons of TNT. Here is the crater it made:
A before-and-after look from the lunar reconnaisance orbiter at the newly formed crater. The 'before' image was taken on Februray 12, 2012, while the 'after' image was shot on July 28th of this year. (LROC) Click to see the animation.
Lunar Reconnaissance Orbiter's LROC camera photographed the crater in July when the spacecraft made a routine pass over the impact site. Subsequent analyses presented at last week's American Geophysical Union meeting linked the crater to the March 17th impact. According to the LROC photo, the crater is 18 meters (59 feet) wide. Together with the bright rays of fresh ejecta ringing the central gouge, the entire impact mark spans an area of lunar terrain half the size of an American football field.
Unlike Earth, which has an atmosphere to protect it, the airless Moon is baldly exposed to incoming asteroids. NASA's Meteoroid Environment Office monitors the lunar surface for signs of ongoing impacts. Since 2005 they have detected flashes of light from more than 300 explosions. The March 17th event was the brightest they'd ever seen, 10 times more luminous than any other lunar meteor in the history of the program. LROC's detection of a crater in Mare Imbrium provides the kind of "ground truth" measurement they need to calibrate the entire dataset.
Unlike Earth, which has an atmosphere to protect it, the airless Moon is baldly exposed to incoming asteroids. NASA's Meteoroid Environment Office monitors the lunar surface for signs of ongoing impacts. Since 2005 they have detected flashes of light from more than 300 explosions. The March 17th event was the brightest they'd ever seen, 10 times more luminous than any other lunar meteor in the history of the program. LROC's detection of a crater in Mare Imbrium provides the kind of "ground truth" measurement they need to calibrate the entire dataset.
Nova Centauri 2013 Update (December 15, 2013)
V1369 Nova Centauri 2013 just above beta Centauri at 4:05 am ACDST 15 December (17:35 Dec 14 UT). Stack of 10 images taken using a Canon IXUS, ASA 400, 10 second each exposure. Images registered and stacked with DeepSkyStacker, the converted to RGB and contrast adjusted in ImageJ. Click to enlarge. (WARNING, very big file, around 40 Mb)
Nova Centauri 2013 (now also called V1369) has undergone some interesting changes since its discovery just under two weeks ago. After reaching a peak brightness of about magnitude 3.5 several days after it blazed into fame on December 2nd, the nova faded quickly to around 4.5, but has now bounced back, rebrightening to magnitude 3.4 - 3.5. The current lightcurve for V1369 Nova Centauri 2013 from the AAVSO is shown below.
Aussie amateur astronomer and web blogger, Ian Musgrave, has recently posted some of his observations and thoughts on this new star:
" While watching this mornings Geminid meteor shower I got to see V1369 nova Centauri 2013 at a decent height above the horizon, making it easier to estimate the magnitude of the lovely nova.
Note I said "easier", not easy. Even at 4 am the nova is still close to the horizon with significant atmospheric extinction (see top left image).
By unaided eye it looked to be about the brightness of Beta Muscae (magnitude 3.54). When you factor in atmospheric extinction this means its real magnitude is on the order of 3.4.
I also measured the intensities of the star on my photographic images (refernce stars Epsilon Cent, 2.3, Eta Crucis, 3.58, Beta Musc 3.54, Alpha Cricinus, 3.16 and Lambda Cent, 3.1 - see image below) and did a linear regression. This gave a magnitude of 3.2 for the nova. This is a bit on the high side (star brightness on digital images do not always reflect their V magnitude), but makes me confident my estimate of 3.4 is in the right ball park.
This is consistent with other observers who found that the nova was around magnitude 3.4 at this time, coming down from a peak of 3.3 at 0 UT."
" While watching this mornings Geminid meteor shower I got to see V1369 nova Centauri 2013 at a decent height above the horizon, making it easier to estimate the magnitude of the lovely nova.
Note I said "easier", not easy. Even at 4 am the nova is still close to the horizon with significant atmospheric extinction (see top left image).
By unaided eye it looked to be about the brightness of Beta Muscae (magnitude 3.54). When you factor in atmospheric extinction this means its real magnitude is on the order of 3.4.
I also measured the intensities of the star on my photographic images (refernce stars Epsilon Cent, 2.3, Eta Crucis, 3.58, Beta Musc 3.54, Alpha Cricinus, 3.16 and Lambda Cent, 3.1 - see image below) and did a linear regression. This gave a magnitude of 3.2 for the nova. This is a bit on the high side (star brightness on digital images do not always reflect their V magnitude), but makes me confident my estimate of 3.4 is in the right ball park.
This is consistent with other observers who found that the nova was around magnitude 3.4 at this time, coming down from a peak of 3.3 at 0 UT."
Labelled expanded image taken using the Canon IXUS, ASA 400, 15 second exposure, 3x Zoom. Central portion of the image to the left, with magnitude comparison stars and the nova indicated. Click to enlarge.
This makes V1369 Nova Centauri the brightest nova since 1999 (V382 Velorum, M2.6), and the 12th brightest nova since 1891! A good article on nova Centauri 2013 is here.
It should also be noted that other astronomers have also been posting comments on the AAVSO forum for this star that indicate that the star's brightness may be oscillating very rapidly, but there is not enough coverage around the world to see a pattern clearly yet. As eluded to by Ian Musgrave, the low altitude of the star from most observer's locations may be interfering with accurate brightness measurements. However, some data (Dec 5th) has shown clear evidence of a strong normalized P-Cygni signature in the star's spectrum, indicating a uniform rapidly expanding spherical shell of ejecta around the host star (v ~900km/s!). Further observations over the last few days also show oscillating changes in the strength of these spectral features while H-alpha lines seem to be growing in brightness again.
In simple terms what these results seem to indicate is that, basically, Nova Centauri 2013 will be visible to the unaided eye for some time yet! So, southern observers, you are encouraged to get out there, have a look and keep tracking the variations in this spectacular 'new' star!
It should also be noted that other astronomers have also been posting comments on the AAVSO forum for this star that indicate that the star's brightness may be oscillating very rapidly, but there is not enough coverage around the world to see a pattern clearly yet. As eluded to by Ian Musgrave, the low altitude of the star from most observer's locations may be interfering with accurate brightness measurements. However, some data (Dec 5th) has shown clear evidence of a strong normalized P-Cygni signature in the star's spectrum, indicating a uniform rapidly expanding spherical shell of ejecta around the host star (v ~900km/s!). Further observations over the last few days also show oscillating changes in the strength of these spectral features while H-alpha lines seem to be growing in brightness again.
In simple terms what these results seem to indicate is that, basically, Nova Centauri 2013 will be visible to the unaided eye for some time yet! So, southern observers, you are encouraged to get out there, have a look and keep tracking the variations in this spectacular 'new' star!
Geminid Meteor Shower Punches Its Way Through A Serious Moonlight
With apologies to David Bowie, some amateur astronomers were dancing under the moonlight, the serious moonlight, as the Geminid meteor shower rained down through its peak on Saturday morning.
The Geminids are subsiding now as Earth begins exiting a stream of debris from rock comet 3200 Phaethon. Preliminary counts by the International Meteor Organization suggest that the shower peaked near 06:11 UTC on Dec. 14th with more than 100 meteors per hour. Bright moonlight reduced the visibility of many faint meteors. Fortunately, the shower was rich in fireballs like this one:
The Geminids are subsiding now as Earth begins exiting a stream of debris from rock comet 3200 Phaethon. Preliminary counts by the International Meteor Organization suggest that the shower peaked near 06:11 UTC on Dec. 14th with more than 100 meteors per hour. Bright moonlight reduced the visibility of many faint meteors. Fortunately, the shower was rich in fireballs like this one:
Amateur astronomer Thomas Ashcraft recorded the fireball using an all-sky camera and a 61 MHz radio receiver. Watch the movie here and turn up the volume. The soundtrack is the echo of a distant TV transmission bouncing off the ionized trail of the disintegrating meteoroid. "By listening to the radio echoes, I could tell there was a strong display of meteors all through the night," says Ashcraft. "We were lucky that some Geminid fireballs appeared through holes in our cloudy skies."
The shower is subsiding, but it's not over. Earth will be inside the debris stream of 3200 Phaethon for some days to come. Look west during the
magic hour before sunrise, and you still could see dozens of Geminids between now and Dec. 17th.
The shower is subsiding, but it's not over. Earth will be inside the debris stream of 3200 Phaethon for some days to come. Look west during the
magic hour before sunrise, and you still could see dozens of Geminids between now and Dec. 17th.
To Delta Geminorum By Way of Jupiter & Pluto (December 13, 2013)
by Bob King, astrobob.areavoices.com
Jupiter is so close to the double star Delta Geminorum, it’s not easy to separate the two at a glance. The two will be within a degree of each other for the next week. The map shows the sky around 10 p.m. local time facing east. Stellarium
The other night I looked up at the constellation Gemini near Jupiter and noticed a star missing. Where the heck was Delta Geminorum? Finally, I found it sitting so close to Jupiter it was almost lost in the planet’s glare. A quick look through the telescope showed the pair separated by less than a quarter degree.
Jupiter presented his usual striped equatorial cloud belts and a nice spread of moons, and Delta, also known by its Arabic name “Wasat”, looked like a single, ordinary star directly south of the planet. While interesting to see a planet and star so close, the pair was certainly not extraordinary.
But if you up the magnification to 150x or higher, you’d discover that Delta’s accompanied by an 8th magnitude companion star snuggled to its southwest. The two stars are close by naked eye standards – just 5.8 arc seconds or 1/300 the width of a full moon – but easily cleave with a 6-inch telescope in good seeing.
Jupiter presented his usual striped equatorial cloud belts and a nice spread of moons, and Delta, also known by its Arabic name “Wasat”, looked like a single, ordinary star directly south of the planet. While interesting to see a planet and star so close, the pair was certainly not extraordinary.
But if you up the magnification to 150x or higher, you’d discover that Delta’s accompanied by an 8th magnitude companion star snuggled to its southwest. The two stars are close by naked eye standards – just 5.8 arc seconds or 1/300 the width of a full moon – but easily cleave with a 6-inch telescope in good seeing.
Jupiter and moons and the double star Wasat (Delta Gem) through a 10-inch scope on Dec. 10, 2013. The two were only a quarter degree apart. Sketch by Bob King
Jupiter and Delta are now so close you might have trouble separating them with your naked eye the next few nights. This is exactly what makes this a great time to pursue this interesting double star in your telescope. Just point it at Jupiter and you’re there. The two will slowly separate in the coming nights, but will stay within a degree of each other through the 20th.
Wasat lies 59 light years from Earth and its companion, a K-class orange dwarf a little smaller than the sun, is 9.3 billion miles or over 100 times farther from the primary star than the Earth is from the sun. This great distance means a long, long time for it to complete an orbit – 1,200 years!
Wasat lies 59 light years from Earth and its companion, a K-class orange dwarf a little smaller than the sun, is 9.3 billion miles or over 100 times farther from the primary star than the Earth is from the sun. This great distance means a long, long time for it to complete an orbit – 1,200 years!
Clyde Tombaugh discovered Pluto in Jan.-Feb. 1930 when it was just as close to Wasat as Jupiter is now. Stellarium
Wasat or Delta Geminorum has another claim to fame. It was here that the dwarf planet Pluto was discovered by American astronomer Clyde Tombaugh in January 1930. Tombaugh took exposures of the sky near Delta on January 23 and 29, 1930. On Feb. 15 when he examined the images, he detected a shift in the position of a 15th magnitude speck (the future Pluto) compared to photos made on Jan. 21. Lowell Observatory in Flagstaff, Arizona, where he worked, announced the discovery to the world on March 13, 1930.
Wasat – ordinary star indeed!
Wasat – ordinary star indeed!
Ice Water Plumes on Europa
(December 12, 2013)
by Camille Carlisle, www.SkyandTelescope.com
New Hubble Space Telescope observations suggest that Jupiter's icy moon spits out water vapor from its surface.
UV observations from Hubble show the size of water vapor plumes coming from Europa’s south pole (Artist’s impression. Credit: NASA, ESA, and M. Kornmesser)
Europa might be leaking.
Astronomers have detected faint emission above the Jovian moon’s southern hemisphere that might be from water vapor spewing from the surface, Lorenz Roth (Southwest Research Institute and University of Cologne, Germany) and colleagues reported December 12th at the American Geophysical Union meeting. The result also appears in Science.
This detection is not the first of potential activity. “The history of apparent plumes on Europa has been somewhat of a sordid one,” says planetary scientist Robert Pappalardo (JPL). Both Voyager and Galileo have seen hints that were later dismissed (one was a ghost image from a previous exposure). A thermal observation from a couple of decades ago also suggested an outburst but couldn’t be reproduced, he adds.
Astronomers have detected faint emission above the Jovian moon’s southern hemisphere that might be from water vapor spewing from the surface, Lorenz Roth (Southwest Research Institute and University of Cologne, Germany) and colleagues reported December 12th at the American Geophysical Union meeting. The result also appears in Science.
This detection is not the first of potential activity. “The history of apparent plumes on Europa has been somewhat of a sordid one,” says planetary scientist Robert Pappalardo (JPL). Both Voyager and Galileo have seen hints that were later dismissed (one was a ghost image from a previous exposure). A thermal observation from a couple of decades ago also suggested an outburst but couldn’t be reproduced, he adds.
Artist's illustration of a plume of water vapor erupting from the icy surface of Jupiter's moon Europa. New Hubble observations provide the best evidence yet that such plumes do in fact exist at the moon's south pole.
Kurt Retherford (Southwest Research Institute)
But with a liquid water ocean beneath its peculiar crust, Europa could have plenty of fuel for eruptions. Plus, features in the region Rhadamanthys Linea look kind of like those from fissure eruptions in Hawaii and Iceland, Pappalardo says.
And of course there’s the parallel with Saturn’s little moon Enceladus, which coughs out enough water vapor from its south pole to form the planet’s E ring.
And of course there’s the parallel with Saturn’s little moon Enceladus, which coughs out enough water vapor from its south pole to form the planet’s E ring.
This composite image combines smoothed Hubble Space Telescope ultraviolet data (blue) with a visible image of the leading hemisphere of Europa. Emission from hydrogen and oxygen suggests that plumes of water vapor are erupting from the moon's surface.
Lorenz Roth (SWRI)
Roth and his colleagues pointed the Hubble Space Telescope at Europa to follow up on tantalizing (but inconclusive) 2009 observations. They took ultraviolet spectra of the moon’s tenuous envelope in November and December 2012, timing their observations so that they could easily subtract out other signals moving through the Jupiter system’s harsh radiation environment. They also focused on two important times in Europa’s orbit: its closest and farthest approaches to Jupiter, also known as periapse and apoapse.
From watching Enceladus, scientists expect plume activity to be higher at apoapse. When an icy moon like Enceladus or Europa is close to its planet, the tidal forces stretch and squish it, closing up any cracks in its surface, researcher Francis Nimmo (University of California, Santa Cruz) said at the press conference. But when the moon moves farther away, it becomes “unsquished,” opening the cracks. These open cracks could expose liquid water to the vacuum of space, causing it to boil off as temporary plumes.
Roth’s team found that at apoapse, emission from oxygen atoms above Europa’s south polar region was about three times brighter than the average elsewhere, while hydrogen was at least nine times brighter. The signals were absent during the November periapse, and also in a second periapse observation from 1999.
From watching Enceladus, scientists expect plume activity to be higher at apoapse. When an icy moon like Enceladus or Europa is close to its planet, the tidal forces stretch and squish it, closing up any cracks in its surface, researcher Francis Nimmo (University of California, Santa Cruz) said at the press conference. But when the moon moves farther away, it becomes “unsquished,” opening the cracks. These open cracks could expose liquid water to the vacuum of space, causing it to boil off as temporary plumes.
Roth’s team found that at apoapse, emission from oxygen atoms above Europa’s south polar region was about three times brighter than the average elsewhere, while hydrogen was at least nine times brighter. The signals were absent during the November periapse, and also in a second periapse observation from 1999.
Cassini image of ice geysers on Enceladus (NASA/JPL/SSI)
This is great: it gives scientists a clear scenario to test. If more observations confirm the uptick in hydrogen and oxygen at apoapse, it will be solid evidence for transient plumes on Europa.
“I’ll sleep better knowing that it’s been reproduced,” Pappalardo admits. Seeing the signal in the same wavelength would be convincing, but it’d be even better if observers could catch infrared emission from warmed material, he adds. “I guess I’m 70-ish percent sure now, based on what I see. I bet if they did it again I’d be 90% sure, and then I’d be up at 100 if I saw the infrared.”
Roth and his colleagues are also cautious. Based on the emission, the team thinks it could come from plumes 200 kilometers (125 miles) tall, spitting out 7 tons of material each second. (Yeah, the team was surprised, too.) That’s 35 times higher than the rate at Enceladus, although the expected plume densities are similar.
Even though the team expects that eruption velocities might hit 700 meters per second (1,500 mph), Roth noted that the vapor won’t reach escape velocity. Instead, it’ll rain back down on the moon, freezing immediately on the -150° C (-240° F) surface, he explained. The whole process would take about 20 minutes.
For now, the only images of Europa’s pole are partial ones from theGalileo spacecraft, which visited the Jupiter system from 1995 to 2003. But the resolution of those images is maybe 100 km per pixel at best, not enough to look for signs of fallout, James Green (NASA Planetary Sciences Division) said during the conference.
Pappalardo and others are working on a Europa Clipper mission concept, which could potentially fly through a plume (if they exist) and study it. NASA hasn’t yet selected the idea for development as a future mission, in part because the clipper would be a flagship-class mission (a.k.a. more than $1 billion U.S.), and the current budget climate won’t allow it. It’ll have to wait until later in the decade.
“I’ll sleep better knowing that it’s been reproduced,” Pappalardo admits. Seeing the signal in the same wavelength would be convincing, but it’d be even better if observers could catch infrared emission from warmed material, he adds. “I guess I’m 70-ish percent sure now, based on what I see. I bet if they did it again I’d be 90% sure, and then I’d be up at 100 if I saw the infrared.”
Roth and his colleagues are also cautious. Based on the emission, the team thinks it could come from plumes 200 kilometers (125 miles) tall, spitting out 7 tons of material each second. (Yeah, the team was surprised, too.) That’s 35 times higher than the rate at Enceladus, although the expected plume densities are similar.
Even though the team expects that eruption velocities might hit 700 meters per second (1,500 mph), Roth noted that the vapor won’t reach escape velocity. Instead, it’ll rain back down on the moon, freezing immediately on the -150° C (-240° F) surface, he explained. The whole process would take about 20 minutes.
For now, the only images of Europa’s pole are partial ones from theGalileo spacecraft, which visited the Jupiter system from 1995 to 2003. But the resolution of those images is maybe 100 km per pixel at best, not enough to look for signs of fallout, James Green (NASA Planetary Sciences Division) said during the conference.
Pappalardo and others are working on a Europa Clipper mission concept, which could potentially fly through a plume (if they exist) and study it. NASA hasn’t yet selected the idea for development as a future mission, in part because the clipper would be a flagship-class mission (a.k.a. more than $1 billion U.S.), and the current budget climate won’t allow it. It’ll have to wait until later in the decade.
Geminid Meteor Shower Approaching Peak Night (December 11, 2013)
This photo shows Geminids streaming away from the shower's radiant near the star Castor. It was made by combining 83 out of 1,256 exposures shot over an 11-hour time span on December 13-14, 2004. Image by Fred Bruenjes.
The onset of the annual Geminid meteor shower means that Earth has begun passage through a stream of debris coming from rock comet 3200 Phaethon. Forecasters expect the shower to peak on Dec. 13-14 with as many as 120 meteors per hour as Earth passes through the densest part of the debris field. For those wishing to observe the event, lunar interference will be a problem, as glare from the nearly-full Moon reduces the number of visible meteors 2- to 5-fold. If it is too cold for a few hours of meteor watching in your location, you can always try an alternative - listen to radar echoes from the Geminids, unaffected by moonlight, on Space Weather Radio. Also, tune into NASA's live web chat about the Geminids on Friday the 13th beginning at 11 pm EST.
Space Shuttle-Sized Asteroid 2013 XY8 to Fly Past Earth on Dec. 11 (December 10, 2013)
by Nancy Atkinson
A newly-discovered asteroid about the size of a space shuttle will fly past Earth on December 11, 2013 at a very safe distance of 760,000 kilometers (470,000 miles). The closest approach of Asteroid 2013 XY8 will be 11:14 UT, and its size is estimated between 31 – 68 meters. This asteroid is zipping along at about 14 kilometers per second, and of course at about 2 lunar distances away, there is no danger of this asteroid hitting Earth. The asteroid was discovered on Dec. 7 by the team at the Catalina Sky Survey, and our friends Ernesto Guido, Nick Howes and Martino Nicolini from the Remanzacco Observatory have provided a follow-up image of the asteroid, taken just this morning.
You can see an animation of it here, and more information at their website.
And as usual with close passing asteroids, the Virtual Telescope Project will is offering a live, online event sharing real-time images of 2013 XY8 with live commentary by their science staff. “It will be a nice opportunity to spy this 40 meter large asteroid moving across the stars,” said Gianluca Masi from the Virtual Telescope Project.
You can see an animation of it here, and more information at their website.
And as usual with close passing asteroids, the Virtual Telescope Project will is offering a live, online event sharing real-time images of 2013 XY8 with live commentary by their science staff. “It will be a nice opportunity to spy this 40 meter large asteroid moving across the stars,” said Gianluca Masi from the Virtual Telescope Project.
Astronomers Discover Giant Planet That Shouldn't Be There (December 10, 2013)
by Vanessa Bailey, University of Arizona Press
An international team of astronomers, led by a University of Arizona graduate student, has discovered the most distantly orbiting planet found to date around a single, sun-like star. It is the first exoplanet -- a planet outside of our solar system -- discovered at the UA.
Weighing in at 11 times Jupiter's mass and orbiting its star at 650 times the average Earth-Sun distance, planet HD 106906 b is unlike anything in our own Solar System and throws a wrench in planet formation theories.
"This system is especially fascinating because no model of either planet or star formation fully explains what we see," said Vanessa Bailey, who led the research. Bailey is a fifth-year graduate student in the UA's Department of Astronomy.
It is thought that planets close to their stars, like Earth, coalesce from small asteroid-like bodies born in the primordial disk of dust and gas that surrounds a forming star. However, this process acts too slowly to grow giant planets far from their star. Another proposed mechanism is that giant planets can form from a fast, direct collapse of disk material. However, primordial disks rarely contain enough mass in their outer reaches to allow a planet like HD 106906 b to form. Several alternative hypotheses have been put forward, including formation like a mini binary star system.
"A binary star system can be formed when two adjacent clumps of gas collapse more or less independently to form stars, and these stars are close enough to each other to exert a mutual gravitation attraction and bind them together in an orbit," Bailey explained. "It is possible that in the case of the HD 106906 system the star and planet collapsed independently from clumps of gas, but for some reason the planet's progenitor clump was starved for material and never grew large enough to ignite and become a star."
Weighing in at 11 times Jupiter's mass and orbiting its star at 650 times the average Earth-Sun distance, planet HD 106906 b is unlike anything in our own Solar System and throws a wrench in planet formation theories.
"This system is especially fascinating because no model of either planet or star formation fully explains what we see," said Vanessa Bailey, who led the research. Bailey is a fifth-year graduate student in the UA's Department of Astronomy.
It is thought that planets close to their stars, like Earth, coalesce from small asteroid-like bodies born in the primordial disk of dust and gas that surrounds a forming star. However, this process acts too slowly to grow giant planets far from their star. Another proposed mechanism is that giant planets can form from a fast, direct collapse of disk material. However, primordial disks rarely contain enough mass in their outer reaches to allow a planet like HD 106906 b to form. Several alternative hypotheses have been put forward, including formation like a mini binary star system.
"A binary star system can be formed when two adjacent clumps of gas collapse more or less independently to form stars, and these stars are close enough to each other to exert a mutual gravitation attraction and bind them together in an orbit," Bailey explained. "It is possible that in the case of the HD 106906 system the star and planet collapsed independently from clumps of gas, but for some reason the planet's progenitor clump was starved for material and never grew large enough to ignite and become a star."
At only 13 million years old, this young planet still glows from the residual heat of its formation. Because at 2,700 Fahrenheit (about 1,500 degrees Celsius) the planet is much cooler than its host star, it emits most of its energy as infrared rather than visible light. Earth, by comparison, formed 4.5 billion years ago and is thus about 350 times older than HD 106906 b.
Direct imaging observations require exquisitely sharp images, akin to those delivered by the Hubble Space Telescope. To reach this resolution from the ground requires a technology called Adaptive Optics, or AO. The team used the new Magellan Adaptive Optics (MagAO) system and Clio2 thermal infrared camera -- both technologies developed at the UA -- mounted on the 6.5 meter-diameter Magellan telescope in the Atacama Desert in Chile to take the discovery image.
UA astronomy professor and MagAO principal investigator Laird Close said: "MagAO was able to utilize its special Adaptive Secondary Mirror, with 585 actuators, each moving 1,000 times a second, to remove the blurring of the atmosphere. The atmospheric correction enabled the detection of the weak heat emitted from this exotic exoplanet without confusion from the hotter parent star."
"Clio was optimized for thermal infrared wavelengths, where giant planets are brightest compared to their host stars, meaning planets are most easily imaged at these wavelengths," explained UA astronomy professor and Clio principal investigator Philip Hinz, who directs the UA Center for Astronomical Adaptive Optics.
The team was able to confirm that the planet is moving together with its host star by examining Hubble Space Telescope data taken eight years prior for another research program. Using the FIRE spectrograph, also installed at the Magellan telescope, the team confirmed the planetary nature of the companion. "Images tell us an object is there and some information about its properties but only a spectrum gives us detailed information about its nature and composition," explained co-investigator Megan Reiter, a graduate student in the UA Department of Astronomy. "Such detailed information is rarely available for directly imaged exoplanets, making HD 106906 b a valuable target for future study."
"Every new directly detected planet pushes our understanding of how and where planets can form," said co-investigator Tiffany Meshkat, a graduate student at Leiden Observatory in the Netherlands. "This planet discovery is particularly exciting because it is in orbit so far from its parent star. This leads to many intriguing questions about its formation history and composition. Discoveries like HD 106906 b provide us with a deeper understanding of the diversity of other planetary systems."
Direct imaging observations require exquisitely sharp images, akin to those delivered by the Hubble Space Telescope. To reach this resolution from the ground requires a technology called Adaptive Optics, or AO. The team used the new Magellan Adaptive Optics (MagAO) system and Clio2 thermal infrared camera -- both technologies developed at the UA -- mounted on the 6.5 meter-diameter Magellan telescope in the Atacama Desert in Chile to take the discovery image.
UA astronomy professor and MagAO principal investigator Laird Close said: "MagAO was able to utilize its special Adaptive Secondary Mirror, with 585 actuators, each moving 1,000 times a second, to remove the blurring of the atmosphere. The atmospheric correction enabled the detection of the weak heat emitted from this exotic exoplanet without confusion from the hotter parent star."
"Clio was optimized for thermal infrared wavelengths, where giant planets are brightest compared to their host stars, meaning planets are most easily imaged at these wavelengths," explained UA astronomy professor and Clio principal investigator Philip Hinz, who directs the UA Center for Astronomical Adaptive Optics.
The team was able to confirm that the planet is moving together with its host star by examining Hubble Space Telescope data taken eight years prior for another research program. Using the FIRE spectrograph, also installed at the Magellan telescope, the team confirmed the planetary nature of the companion. "Images tell us an object is there and some information about its properties but only a spectrum gives us detailed information about its nature and composition," explained co-investigator Megan Reiter, a graduate student in the UA Department of Astronomy. "Such detailed information is rarely available for directly imaged exoplanets, making HD 106906 b a valuable target for future study."
"Every new directly detected planet pushes our understanding of how and where planets can form," said co-investigator Tiffany Meshkat, a graduate student at Leiden Observatory in the Netherlands. "This planet discovery is particularly exciting because it is in orbit so far from its parent star. This leads to many intriguing questions about its formation history and composition. Discoveries like HD 106906 b provide us with a deeper understanding of the diversity of other planetary systems."
Space Needle Asteroid Makes "Closest Approach" Tonight (December 9, 2013)
An unusual asteroid is making its annual "closest approach" in an unusual sort of way. Sometimes called the "Space Needle", asteroid 1620 Geographos is the most elongated object we know of in the solar system, with dimensions of 5.1 km x 1.8 km (almost 3X as long as it is wide). Some scientists suspect that it may be a giant rubble pile that has been tidally distorted by a close approach to Earth some time in its ancient past. And along with its strange shape, there is an unusual orbit - fairly elliptical - that brings it inside Earth's orbit, then back out again past the orbit of Mars. This year, because of this orbit and the position of the earth in its orbit, 1620 Geographos reaches its closest point to Earth while almost on the opposite side of the Sun, 1.798 AUs away! It sits very low in the western sky these nights, hovering at around magnitude 15 or 16 - an impossible challenge to find given its proximity to the Sun.
The asteroid 1620 Geographos was discovered on September 14, 1951 at the Palomar Observatory by Albert George Wilson and Rudolph Minkowski. It was originally given the provisional designation 1951 RA. Its name, a Greek word meaning "geographer" (geo– 'Earth' + graphos 'drawer/writer'), was chosen to honour geographers and the National Geographic Society.
Because Geographos is a Mars-crosser asteroid and a near-Earth object it belongs to the Apollo group of asteroids. In 1994, during the asteroid's closest approach to Earth in two centuries at 5.0 Gm-which will not be bettered until 2586- a radar study of it was conducted by the Deep Space Network at Goldstone, California. Geographos is an S-type asteroid, meaning that it is highly reflective and composed of nickel-iron mixed with iron- and magnesium-silicates.
Geographos was to be explored by the U.S.'s Clementine mission; however, a malfunctioning thruster ended the mission before it could approach the asteroid.
Because Geographos is a Mars-crosser asteroid and a near-Earth object it belongs to the Apollo group of asteroids. In 1994, during the asteroid's closest approach to Earth in two centuries at 5.0 Gm-which will not be bettered until 2586- a radar study of it was conducted by the Deep Space Network at Goldstone, California. Geographos is an S-type asteroid, meaning that it is highly reflective and composed of nickel-iron mixed with iron- and magnesium-silicates.
Geographos was to be explored by the U.S.'s Clementine mission; however, a malfunctioning thruster ended the mission before it could approach the asteroid.
Andromedid Meteor Outburst in Progress
(December. 8, 2013)
The Canadian Meteor Orbit Radar (CMOR) is detecting an outburst of Andromedid meteors on Dec. 8th. "Meteor rates last night were near 20 per hour (ZHR)," reports Bill Cooke of NASA's Meteoroid Environment Office. "The shower could increase in intensity tonight, so we hope observers (especially Europeans) will be alert for meteors." Andromedid meteoroids come from Comet Biela, which broke apart in the 19th century. The shower's radiant in Cassiopeia is high in the sky after sunset for observers in the Northern Hemisphere. A similar outburst of Andromedids in 2011 was rich in faint meteors. If the 2013 outburst is the same, dark skies will be required to see it. Stay tuned for updates.
Did Any Part of Comet ISON Survive?
(December 7, 2013)
by Tony Philips, www.spaceweather.com
Yesterday morning, Dec. 6th, leading researchers from the Comet ISON Observing Campaign (CIOC) held an informal workshop at the Johns Hopkins Applied Physics Lab. One of the key questions they discussed was, Did Comet ISON survive? It might seem surprising that anyone is still asking. After all, the "comet" that emerged from the sun's atmosphere on Thanksgiving day appeared to be little more than a disintegrating cloud of dust. This movie from the STEREO-A spacecraft (processed by Alan Watson) shows the V-shaped cloud fading into invisibility on Dec. 1st:
The answer hinges on the contents of that cloud. Is it nothing more than a cloud of dust--or could there be some some fragments of the disintegrated nucleus still intact and potentially active?
A key result announced at the workshop comes from SOHO, the Solar and Heliospheric Observatory. According to the spacecraft's SWAN instrument, the comet stopped producing so-called Lyman alpha photons soon after its closest approach to the sun. Karl Battams of the CIOC explains what this means: "Without getting technical, Lyman-Alpha is a consequence of sunlight interacting with hydrogen, and if we are not seeing that interaction then it means that the levels of hydrogen (and hence ice) are extremely low. This is indicative of a completely burned out nucleus, or no nucleus at all."
"The evidence appears strong that at some point approaching perihelion - whether days or hours - Comet ISON likely began to completely fall apart," he continues. "What remains of ISON now is going to be either just a cloud of dust, or perhaps a few very depleted chunks of nucleus. Either way, it's not going to flare up at this point and we should assume the comet's show is over."
"However, we do need to verify this," says Battams. "Hopefully the Hubble team can come to the rescue! In mid-December, Hubble will be pointed in the direction of where ISON should be and they'll try and image something. If no fragments are surviving, or they are tiny, then Hubble will not be able to find anything, but that negative detection will tell us something: namely that ISON is indeed gone for good."
Observer's Note: This morning Dec. 7, J. J. Gonzalez of Spain made a definitive observation of the comet with an 8-inch (20 cm) telescope at magnitude 7.2 from his dark, mountaintop location. He described it as 10 arc minutes across (30 arc minutes = one full moon diameter), elliptical in shape and nearly smooth with very little brightening toward its center. Gonzalez also spied two faint, tail-like structures extending to the south and northwest. I suspect the digital imagers will be out in force over the weekend. We’ll know very soon what ISON’s ghost looks like from the ground.
A key result announced at the workshop comes from SOHO, the Solar and Heliospheric Observatory. According to the spacecraft's SWAN instrument, the comet stopped producing so-called Lyman alpha photons soon after its closest approach to the sun. Karl Battams of the CIOC explains what this means: "Without getting technical, Lyman-Alpha is a consequence of sunlight interacting with hydrogen, and if we are not seeing that interaction then it means that the levels of hydrogen (and hence ice) are extremely low. This is indicative of a completely burned out nucleus, or no nucleus at all."
"The evidence appears strong that at some point approaching perihelion - whether days or hours - Comet ISON likely began to completely fall apart," he continues. "What remains of ISON now is going to be either just a cloud of dust, or perhaps a few very depleted chunks of nucleus. Either way, it's not going to flare up at this point and we should assume the comet's show is over."
"However, we do need to verify this," says Battams. "Hopefully the Hubble team can come to the rescue! In mid-December, Hubble will be pointed in the direction of where ISON should be and they'll try and image something. If no fragments are surviving, or they are tiny, then Hubble will not be able to find anything, but that negative detection will tell us something: namely that ISON is indeed gone for good."
Observer's Note: This morning Dec. 7, J. J. Gonzalez of Spain made a definitive observation of the comet with an 8-inch (20 cm) telescope at magnitude 7.2 from his dark, mountaintop location. He described it as 10 arc minutes across (30 arc minutes = one full moon diameter), elliptical in shape and nearly smooth with very little brightening toward its center. Gonzalez also spied two faint, tail-like structures extending to the south and northwest. I suspect the digital imagers will be out in force over the weekend. We’ll know very soon what ISON’s ghost looks like from the ground.
Comet Lovejoy Becomes the New Comet ISON (December 6, 2013)
While some people are still mourning the loss of comet ISON, another one, comet Lovejoy C/2013 R1 has quietly become the rock star of the night sky. Still visible to the unaided eye at magnitude 4.6 in northern part of the constellation Corona Borealis, its has grown a beautiful tail and is expected to maintain its brightness into the new year. Amateur astronomers around the world are reporting that the tail of the comet now can be seen with the naked eye stretching 5 degrees behind the comet's nucleus - at least double that length can be captured with a 20 second exposure with a tripod-mounted camera.
Telescopes and longer exposures reveal much more. This image from Michael Jäger of Masenberg, Austria, shows a "disconnection event" disrupting the comet's tail on Dec. 5th. The disturbance could be caused by a gust of solar wind or perhaps an episode of vigorous outgassing in the comet's core.
Monitoring is encouraged. Comet Lovejoy is easy to find before dawn rising in the east before the sun. Sky maps: Dec. 6, 7, 8, 9.
Telescopes and longer exposures reveal much more. This image from Michael Jäger of Masenberg, Austria, shows a "disconnection event" disrupting the comet's tail on Dec. 5th. The disturbance could be caused by a gust of solar wind or perhaps an episode of vigorous outgassing in the comet's core.
Monitoring is encouraged. Comet Lovejoy is easy to find before dawn rising in the east before the sun. Sky maps: Dec. 6, 7, 8, 9.
A closeup of the jets emanating from comet Lovejoy's nucleus. Taken by Lorenzo Comolli on December 5, 2013 @ Tradate, Italy
Geminid Meteor Shower Already Firing Up (December 4, 2013)
by Tony Philips, www.spaceweather.com
Earth is entering a stream of debris from rock comet 3200 Phaethon, source of the annual Geminid meteor shower. Our planet is just dipping into the outskirts of the debris zone now, so visual meteor rates are low. Nevertheless, the Canadian Meteor Orbit Radar (CMOR) is starting to pick up echoes from Geminid meteoroids. This Dec. 4th radar map shows a concentration of activity in the constellation Gemini:
"The Geminids, still ten days from their maximum, are very clearly visible in the latest CMOR data," reports Prof. Peter Brown of the University of Western Ontario, which operates the radar.
In the radar map, the Geminid radiant is labeled 'GEM.' A second nearby radiant labeled 'NOO' marks the location of the November omega Orionids, a minor shower that peaks in early December.
The Geminids won't peak until Dec. 13-14 when Earth passes through the core of the debris stream, but Brown thinks observers should start looking now. "Glare from the nearly-full Moon will interfere with the Geminid's maximum in mid-December," he says. "This week, however, the Moon is new. Observers should be starting to see activity from this very strong shower." Observing tip: The best time to look is during the hours between midnight and dawn when the constellation Gemini is high in the sky.
In the radar map, the Geminid radiant is labeled 'GEM.' A second nearby radiant labeled 'NOO' marks the location of the November omega Orionids, a minor shower that peaks in early December.
The Geminids won't peak until Dec. 13-14 when Earth passes through the core of the debris stream, but Brown thinks observers should start looking now. "Glare from the nearly-full Moon will interfere with the Geminid's maximum in mid-December," he says. "This week, however, the Moon is new. Observers should be starting to see activity from this very strong shower." Observing tip: The best time to look is during the hours between midnight and dawn when the constellation Gemini is high in the sky.
Naked-Eye Nova Pops to Life in Centaurus
(December 3, 2013)
by Alan MacRobert, www.SkyandTelescope.com
It’s out of sight from the Northern Hemisphere, but a nova has erupted to 5th magnitude just west of Alpha and Beta Centauri. Nova hunter John Seach in Australia caught it on December 2nd with a DSLR patrol camera at about magnitude 5.5. Nothing there was as bright as 11th magnitude in his previous images taken on November 26th.
The next night, December 3rd, Ernesto Guido, Nick Howes, and Martino Nicolini used a remotely-operated 20-inch scope to take the close-up image at right. By then variable-star observers were calling it magnitude 4.7 or 4.6, and spectra were showing a nova’s strong hydrogen emission lines.
The next night, December 3rd, Ernesto Guido, Nick Howes, and Martino Nicolini used a remotely-operated 20-inch scope to take the close-up image at right. By then variable-star observers were calling it magnitude 4.7 or 4.6, and spectra were showing a nova’s strong hydrogen emission lines.
A closeup of the presumed Nova Centauri 2013 shining at 5th magnitude on December 3rd. Click on the image for a blink comparison with a Digitized Sky Survey image. The nova is almost exactly on top of a previously 15th-magnitude star.
E. Guido / N. Howes / M. Nicolini
Is it still brightening? If you’re in the south temperate latitudes, see for yourself! The nova is moderately high in the south-southeast before your local start of morning twilight. It's at right ascension 13h 54m 45s, declination —59° 09.1′, almost perfectly centered on the location of a previously 15th-magnitude star.
Its preliminary designation is PNV J13544700-5909080. Here’s a 10°-wide comparison-star chart from the AAVSO. The nova is centered on the chart, and the bright star is Beta Cen.
Its preliminary designation is PNV J13544700-5909080. Here’s a 10°-wide comparison-star chart from the AAVSO. The nova is centered on the chart, and the bright star is Beta Cen.
Now is a Great Time to Try Seeing Venus in the Daytime Sky (December 3, 2013)
by David Dickinson, www.UniverseToday.com
Venus (arrowed) imaged near the waning crescent Moon on August 13th, 2012. (Photo by author).
Here’s a feat of visual athletics to amaze your friends with this week. During your daily routine, you may have noticed the daytime Moon hanging against the azure blue sky. But did you know that, with careful practice and a little planning, you can see Venus in the broad daylight as well?
This week offers a great chance to try, using the daytime Moon as a guide. We recently wrote about the unique circumstances of this season’s evening apparition of the planet Venus. On Friday, December 6th, Venus will reach a maximum brilliancy of magnitude -4.7, over 16 times brighter than Sirius, the brightest star in the sky. And just one evening prior on Thursday December 5th, the 3-day old crescent Moon passes eight degrees above it, slightly closer together than the span of your palm held at arm’s length.
This week offers a great chance to try, using the daytime Moon as a guide. We recently wrote about the unique circumstances of this season’s evening apparition of the planet Venus. On Friday, December 6th, Venus will reach a maximum brilliancy of magnitude -4.7, over 16 times brighter than Sirius, the brightest star in the sky. And just one evening prior on Thursday December 5th, the 3-day old crescent Moon passes eight degrees above it, slightly closer together than the span of your palm held at arm’s length.
The orientation of Venus and the Moon on Thursday, December 5th as it crosses the local meridian at 3PM EST. Created using Starry Night Education software.
The Moon will thus make an excellent guide to spot Venus in the broad daylight. It’s even possible to nab the pair with a camera, if you can gauge the sky conditions and tweak the manual settings of your DSLR just right.
The best time to attempt this feat on Thursday will be when the pair transits the local meridian due south of your location. Deep in the southern hemisphere, the Moon and Venus will appear to transit to the north. This occurs right around 3:00 PM local. The fingernail Moon will be easy to spot, then simply begin scanning the sky to the south of it with the naked eye or binoculars for the brilliant diamond of Venus. High contrast and blocking the Sun out of view is key — Venus will easily pop right out against a clear deep blue sky, but it may disappear all together against a washed out white background.
The Moon will be at a 10% illuminated phase on Thursday, while Venus presents a slimming crescent at 27% illumination. Though tougher to find, Venus is actuallybrighter than the Moon in terms of albedo… expand it up to the apparent size of a Full Moon and it would be over four times as bright!
The best time to attempt this feat on Thursday will be when the pair transits the local meridian due south of your location. Deep in the southern hemisphere, the Moon and Venus will appear to transit to the north. This occurs right around 3:00 PM local. The fingernail Moon will be easy to spot, then simply begin scanning the sky to the south of it with the naked eye or binoculars for the brilliant diamond of Venus. High contrast and blocking the Sun out of view is key — Venus will easily pop right out against a clear deep blue sky, but it may disappear all together against a washed out white background.
The Moon will be at a 10% illuminated phase on Thursday, while Venus presents a slimming crescent at 27% illumination. Though tougher to find, Venus is actuallybrighter than the Moon in terms of albedo… expand it up to the apparent size of a Full Moon and it would be over four times as bright!
Church and Venus as seen from Westgate River Ranch, Florida. Photo by author.
You’ll be amazed what an easy catch Venus is in the daytime once you’ve spotted it — we’ve included views of Venus in the daytime when visible during sidewalk star parties for years.
Due to its brilliancy, Venus has also been implicated in more UFO sightings than any other planet, and even caused the Indian Army to mistake the pair for snooping Chinese drones earlier this year when it was in conjunction with the planet Jupiter. A daytime sighting of the planet Venus near the Moon was almost certainly the “curious star” reported by startled villagers observing from Saint-Denis, France on January 13th, 1589.
Venus can also cast a noticeable shadow near greatest brilliancy, an effect that can be discerned against a fresh snow-covered landscape. Can’t see it? Take a time exposure shot of the ground and you may just be able to tease it out… but hurry, as the waxing Moon will soon be dominating the early evening night sky show!
Another phenomenon to watch for this week on the face of the waxing crescent Moon is known as Earthshine. Can you just make out the dark limb of the Moon? This is caused by the Earth acting as a “mirror” reflecting sunlight back at the nighttime side of the Moon. And don’t forget, China’s Chang’e-3 lander plus rover will be landing on the lunar surface in the Sinus Iridum region later this month on December 14th, the first lunar soft landing since 1976!
The imaginary line of the ecliptic currently bisects the Moon and Venus, as Venus sits at an extreme southern point 2.5 degrees below the ecliptic — in fact, 2013 the farthest south it’s been since 1930 — and the Moon sits over four degrees above the ecliptic this week. The Moon also reached another notable point today, as it reached its most northern “southerly point” for 2013 at a declination of -19.6 degrees. The Moon’s apparent path is headed for a “shallow year” in 2015, after which it’ll begin to slowly widen over its 18.6 year cycle out to a maximum declination range in 2024. It’s a weird but true fact that the motion of the Moon is not fixed to the Earth’s equatorial plane, but to the path of our orbit traced out by the ecliptic, to which its orbit is tilted an average of five degrees.
Due to its brilliancy, Venus has also been implicated in more UFO sightings than any other planet, and even caused the Indian Army to mistake the pair for snooping Chinese drones earlier this year when it was in conjunction with the planet Jupiter. A daytime sighting of the planet Venus near the Moon was almost certainly the “curious star” reported by startled villagers observing from Saint-Denis, France on January 13th, 1589.
Venus can also cast a noticeable shadow near greatest brilliancy, an effect that can be discerned against a fresh snow-covered landscape. Can’t see it? Take a time exposure shot of the ground and you may just be able to tease it out… but hurry, as the waxing Moon will soon be dominating the early evening night sky show!
Another phenomenon to watch for this week on the face of the waxing crescent Moon is known as Earthshine. Can you just make out the dark limb of the Moon? This is caused by the Earth acting as a “mirror” reflecting sunlight back at the nighttime side of the Moon. And don’t forget, China’s Chang’e-3 lander plus rover will be landing on the lunar surface in the Sinus Iridum region later this month on December 14th, the first lunar soft landing since 1976!
The imaginary line of the ecliptic currently bisects the Moon and Venus, as Venus sits at an extreme southern point 2.5 degrees below the ecliptic — in fact, 2013 the farthest south it’s been since 1930 — and the Moon sits over four degrees above the ecliptic this week. The Moon also reached another notable point today, as it reached its most northern “southerly point” for 2013 at a declination of -19.6 degrees. The Moon’s apparent path is headed for a “shallow year” in 2015, after which it’ll begin to slowly widen over its 18.6 year cycle out to a maximum declination range in 2024. It’s a weird but true fact that the motion of the Moon is not fixed to the Earth’s equatorial plane, but to the path of our orbit traced out by the ecliptic, to which its orbit is tilted an average of five degrees.
The view looking west tonight from latitude 30 degrees north. Created using Stellarium.
And speaking of the Moon, there’s another fun naked-eye feat you can attempt tonight. At dusk, U.S. East Coast observers might just be able to pick up the razor thin crescent Moon hanging low to the West, only 23 hours past New. Begin scanning the western horizon about 10 minutes after sunset. Can you see it with binoculars? The naked eye? Chances get better for sighting the slim crescent Moon the farther west you go. North American observers will have a chance at a “personal best” during next lunation in the first few days of 2014… more to come!
Comet ISON Update (December 2, 2013)
by Bob King, Astrobob.areavoices.com
Just a brief update today. Comet ISON has left the eyes of SOHO, but it’s still there in STEREO-A through Dec. 7 and possibly longer if NASA decides to roll the spacecraft for a better view in the coming days. I checked today but no recent, high-res photos have been uploaded yet. I’ll post them when they arrive. You can still see what's left of the comet in the upper right-hand corner of the low-resolution picture below:
The International Astronomical Union has published an electronic telegram No. 3731 today Dec. 1 with blow-by-blow scientific observations of ISON’s evolution during perihelion. Here’s a quick summary of the results:
* The comet’s nucleus disrupted hours before perihelion with the comet’s head fading from -2 magnitude (just shy of Jupiter’s brightness) to well below +1 magnitude shortly before perihelion.
* What remains after perihelion is a diffuse cloud of dust from the nucleus mostly transparent to the background stars. Late on Nov. 30 the main part of the cloud spanned about 1/2 degree and glowed weakly at magnitude 5.4.
* Z. Sekanina of the Jet Propulsion Laboratory, studying SOHO images, determined that ISON stopped producing dust 3 hours before perihelion. This jives with the photos taken shortly after perihelion showing that a sharp tip had replaced the larger, rounded nucleus.
* The nucleus or core of the comet is thought to have fragmented shortly before a sudden surge in brightness seen nearly 12 hours prior to perihelion.
* ISON’s post-perihelion, sunward-pointing tail may be composed of dust grains released 1-2 days before perihelion, while the eastward pointing tail (sticking out to the left of the comet) was made of dust released within an hour of perihelion and likely composed of graphite and metals.The streamer of much larger dust grains ejected long before the comet was near the sun completely disappeared during the comet’s near-brush with the sun.
* The comet’s nucleus disrupted hours before perihelion with the comet’s head fading from -2 magnitude (just shy of Jupiter’s brightness) to well below +1 magnitude shortly before perihelion.
* What remains after perihelion is a diffuse cloud of dust from the nucleus mostly transparent to the background stars. Late on Nov. 30 the main part of the cloud spanned about 1/2 degree and glowed weakly at magnitude 5.4.
* Z. Sekanina of the Jet Propulsion Laboratory, studying SOHO images, determined that ISON stopped producing dust 3 hours before perihelion. This jives with the photos taken shortly after perihelion showing that a sharp tip had replaced the larger, rounded nucleus.
* The nucleus or core of the comet is thought to have fragmented shortly before a sudden surge in brightness seen nearly 12 hours prior to perihelion.
* ISON’s post-perihelion, sunward-pointing tail may be composed of dust grains released 1-2 days before perihelion, while the eastward pointing tail (sticking out to the left of the comet) was made of dust released within an hour of perihelion and likely composed of graphite and metals.The streamer of much larger dust grains ejected long before the comet was near the sun completely disappeared during the comet’s near-brush with the sun.
This composite time-lapse image shows Comet ISON approaching and leaving during its slingshot around the sun – represented by the white circle -- on Nov. 28, 2013. The ISON images clearly outline the curve of the comet's orbit path, the dimming of the nucleus just before perihelion (under the solar disk), and the revival in brightness of the nucleus and tail shortly after perihelion. What is not shown are the most recent images of the comet which display the dimming and dispersal of the cometary cloud of debris in the days after perihelion. The images were captured by ESA/NASA's SOHO mission. Credit: ESA/NASA/SOHO/SDO/GSFC
Ok, Funeral Back On For Comet ISON...Its Gone! (December 1, 2013)
Whatever small piece or pieces of comet ISON that survived its blazingly close encounter with the Sun now appear to have disintegrated and the remaining cloud of debris is dispersing quicky, according to the latest reports from scientists monitoring the comet with the SOHO and SDO spacecraft. A brief morning update (EST) from Karl Battams, who studies sungrazing comets at the Naval Research Laboratory, confirms social media reports that Comet C/2012 S1 ISON appears to be getting fainter in images from the Solar and Heliospheric Observatory (SOHO). (To see the changes since closest approach, click on the time-lapse movie below). “Comet #ISON really is fading fast and I no longer see any sign of a “central condensation” (i.e. no obvious indication of a nucleus…),” Karl Battams, lead analyst for NASA's Comet ISON Observing Campaign, wrote on Twitter. “I *do* think that something emerged from the Sun, but probably a v.small nucleus or “rubble pile”, and I fear that may have now dissolved.” Later he added, "If #ISON had a nucleus -- note: *IF* -- then I'd say it's now about mag +7 in the image (at the bottom of this article.) It's the faint smudge at 1pm position) "
The remaining cometary cloud is so diffuse and is dispersing so quickly that any chance of a visual observation by ground-based observers in the morning sky seems very remote. If the comet's nucleus had stayed together, astronomers predicted that it may have been visible to backyard observers as early as this morning. However, being as dim and diffuse as it now is, any chance to see it from Earth will have to wait until the cloud has moved farther in its orbit away from the Sun. Astrophotographers may have a somewhat better shot at getting some sort of image of the debris field. Time will tell if we get one last look at what was a pretty spectacular little dirty snowball.
UPDATE: For further details as to what really happened to Comet ISON during its perihelion passage, check out this summary of comments and analyses by professional astronomers through the Central Bureau for Astronomical Telegrams (CBAT). It is well worth the read!
The remaining cometary cloud is so diffuse and is dispersing so quickly that any chance of a visual observation by ground-based observers in the morning sky seems very remote. If the comet's nucleus had stayed together, astronomers predicted that it may have been visible to backyard observers as early as this morning. However, being as dim and diffuse as it now is, any chance to see it from Earth will have to wait until the cloud has moved farther in its orbit away from the Sun. Astrophotographers may have a somewhat better shot at getting some sort of image of the debris field. Time will tell if we get one last look at what was a pretty spectacular little dirty snowball.
UPDATE: For further details as to what really happened to Comet ISON during its perihelion passage, check out this summary of comments and analyses by professional astronomers through the Central Bureau for Astronomical Telegrams (CBAT). It is well worth the read!
Move Over ISON, Time to Share the Love with Comet Lovejoy
(November 30, 2013)
by Bob King, astrobob.areavoices.com
Comet Lovejoy (C/2013 R1 Lovejoy) at 2:30 a.m. this morning Nov. 29, 2013. The comet was faintly visible with the naked eye and a pretty sight in binoculars. Details: 70-second exposure, ISO 800, 70mm f/2.8 on a tracking mount. Credit: Bob King
In the furor of following Comet ISON, we’ve almost lost track of another fine, fuzzy fellow – Comet Lovejoy. Last we checked in on this comet during the first half of November, it had swelled to almost half a degree in diameter with a 2-degree-long tail. From a dark sky the comet was even bright enough to glimpse with the naked eye in moonlight.
I’m here to tell you it’s still all of those things. With the moon out of the sky, I could see Lovejoy without difficulty with the naked eye near the star Gamma in the constellation Bootes below the handle of the Big Dipper early this morning. It looked like a small fuzzy blob of magnitude 4.6.
Comet Lovejoy showing magnificent detail in this image taken by Rudi Dobesberger on November 28, 2013 @ Austria / Reichraming. Says Rudi, "This was the first night with little moonlight to see comet Lovejoy with the unaided eyes again,as a small diffuse star in the night sky." Imaged with a TMB 105/650, 4min subs with SBIG STL 11 000.
10×50 binoculars really did the comet justice. With them a beautiful, gossamer tail stretched across half the field of view or about 2.5 degrees. One degree is the amount of sky you can cover with your pinkie finger held at arm’s length. The photos closely match my visual impression of the tail through the 10x50s. Through a 15-inch telescope at low magnification, Lovejoy’s monster-sized head (just under half a degree, the diameter of a full moon) glowed pale blue-green highlighted by a bright, fuzzy dot at its center – the false nucleus. The real comet nucleus always remains hidden in its wraps of dust and gas.
Upping the magnification to 287x, a striking, funnel-shaped fan of dust issued from the false nucleus to the south-southeast. This feature has been a regular part of Lovejoy’s anatomy for at least the past few weeks. I urge observers with 6-inch and larger telescopes to take a look. This amazing jet of dusty material boiling off the comet’s nucleus won’t be visible forever. Use high power and bore right into the coma’s center.
Upping the magnification to 287x, a striking, funnel-shaped fan of dust issued from the false nucleus to the south-southeast. This feature has been a regular part of Lovejoy’s anatomy for at least the past few weeks. I urge observers with 6-inch and larger telescopes to take a look. This amazing jet of dusty material boiling off the comet’s nucleus won’t be visible forever. Use high power and bore right into the coma’s center.
Closeup of Comet Lovejoy’s false nucleus (dot) with a plume of dust sticking out to the left on Nov. 12, 2013. Credit: Luc Arnold
Comet Lovejoy clears the horizon around 1 a.m. (I know -ouch!) but you’ll see it best between 2:30 and the start of dawn when it’s better placed. The comet passed closest to Earth on Nov. 20 – that’s why it’s still bright. As it moves away from Earth it will gradually get dimmer, which makes the coming two moonless weeks the best time to seize the opportunity.
Cancel the Funeral...ISON Not Dead Yet!
(November 29, 2013)
Astronomers can put away their eulogies. Apparently, reports of comet ISON's death have been greatly exaggerated. Well, at least somewhat exaggerated. Oh, alright, we're still not 100% sure, but it looks like some fragment of the nucleus has in fact survived and has started growing a new tail.
Thursday was a day full of excitement and also many questions in regards to Comet ISON. The eyes of sky watchers around the world were tuned into a number of space weather websites wondering if the sungazing comet would survive its close encounter with our star. Comet ISON brightened throughout the day as it neared the sun, with a long dusty tail visible behind it in both LASCO and STEREO imagery. However, worrying signals that the comet was disintegrating came when the head of the comet began to disappear as it came increasingly nearer its moment of closest approach. When it came time for the predicted perihelion at 18:44 UTC, initial indications were that ISON did not survive the intense solar atmosphere and burned up. Comet ISON was declared dead by many. After a few hours had passed, what appeared to be a a cloud or fragment of the comet re-emerged in both LASCO C2 and STEREO Ahead coronagraph imagery. Did ISON survive? Imagery and video below appear to support that scenario. More updates to follow regarding this event. Stay Tuned!
UPDATE: In the updated video below by STEREO Behind COR2, it captures the close encounter from the approach, perihelion (closest distance to the sun), and finally after a near death experience, the exit. Towards the end of the video you can see what appears to be the tail reforming and changing directions as the flow of the solar wind streams past it. This is a normal occurrence when any sungrazing comet prepares to travel back into our solar system. More updates to follow as more information comes in.
Thursday was a day full of excitement and also many questions in regards to Comet ISON. The eyes of sky watchers around the world were tuned into a number of space weather websites wondering if the sungazing comet would survive its close encounter with our star. Comet ISON brightened throughout the day as it neared the sun, with a long dusty tail visible behind it in both LASCO and STEREO imagery. However, worrying signals that the comet was disintegrating came when the head of the comet began to disappear as it came increasingly nearer its moment of closest approach. When it came time for the predicted perihelion at 18:44 UTC, initial indications were that ISON did not survive the intense solar atmosphere and burned up. Comet ISON was declared dead by many. After a few hours had passed, what appeared to be a a cloud or fragment of the comet re-emerged in both LASCO C2 and STEREO Ahead coronagraph imagery. Did ISON survive? Imagery and video below appear to support that scenario. More updates to follow regarding this event. Stay Tuned!
UPDATE: In the updated video below by STEREO Behind COR2, it captures the close encounter from the approach, perihelion (closest distance to the sun), and finally after a near death experience, the exit. Towards the end of the video you can see what appears to be the tail reforming and changing directions as the flow of the solar wind streams past it. This is a normal occurrence when any sungrazing comet prepares to travel back into our solar system. More updates to follow as more information comes in.
Apparently not all of comet ISON was consumed in the 2700 degree furnace trip through the Sun's outer atmosphere. CLICK ON THE IMAGE TO SEE THE PROOF from the vantage point of the Stereo Behind spacecraft.
Comet ISON Destroyed By Sun!
(November 28, 2013)
Comet ISON has apparently disintegrated and its material dispersed after passing through the perihelion point (closest approach) very close to the sun. Evidence from several spacecraft watching the comet as it passed behind the sun, initially indicated that nothing observable has survived the extremely close passage - only 724,000 miles above the sun's surface. Watch the head of the comet fade dramatically as it approaches the sun in this SOHO coronagraph movie:
It will take a few more hours until NASA and other agencies can say for sure what the comet’s fate is, but several astronomers are saying the comet likely died during its closest approach. Apparently the heat and extreme tidal forces exerted on the nucleus were too much for the small dirty snowball. That said, there still is valuable science that can be performed if ISON has broken up, For example, SDO scientists point out that, if any cometary debris containing oxygen (and most comets contain lots of it in their water) is swept out of the comets orbit by the solar wind, they should be able to track it and learn a lot more about how the solar wind behaves as it moves much farther out from the sun. The dispersement of the charged particles as they move away from the sun and their interaction with the interplanetary magnetic field (IMF) would become much easier to study.
ISON coincided with American Thanksgiving, causing a lot of astronomers and journalists to work holiday hours while pundits made jokes about the comet being “roasted” along with the turkey. Meanwhile, amateur astronomer Stuart Atkinson — author of the Waiting for ISON blog — was among those eagerly awaiting the comet’s closest approach.
ISON coincided with American Thanksgiving, causing a lot of astronomers and journalists to work holiday hours while pundits made jokes about the comet being “roasted” along with the turkey. Meanwhile, amateur astronomer Stuart Atkinson — author of the Waiting for ISON blog — was among those eagerly awaiting the comet’s closest approach.
But as the comet made its closest approach, astronomers grew more and more skeptical than it had survived. Phil Plait (who writes the Bad Astronomy blog on Slate) pointed out that the comet’s nucleus appeared much dimmer than its tail in images from SOHO (Solar and Heliospheric Observatory), NASA’s sun-gazing spacecraft. This implied that the nucleus was disintegrating.
Plait and Karl Battams — a Naval Research Laboratory astrophysicist who operates the Sungrazing Comets Project – both participated in a NASA Google+ Hangout on ISON. As of about 2 p.m. EST (7 p.m. UTC), both said that they believe ISON is an “ex-comet”, although it will be a few more hours before scientists can say for sure.
The challenge is that the two spacecraft used to watch ISON swing around the sun — the Solar Dynamics Observatory and SOHO — are not necessarily designed to look for comets. Battams and Plait initially said that it sometimes take additional image processing to view information in it. more As time elapsed though, both expressed extreme skepticism that the comet survived.
Even if the comet is dead, Plait pointed out that scientists can still learn a lot from the remaining debris. ISON is believed to be a pristine example of bodies in the Oort Cloud, a vast body of small objects beyond the orbit of Neptune. Examining the dust in its debris trail could tell scientists more about the origins of the solar system.
UPDATE: 4:40 p.m. EST: On Twitter, the European Space Agency (quoting SOHO scientist Bernhard Fleck) said the comet is gone. Separately, the Naval Research Laboratory’s Karl Battams posted that he thinks recent observations show debris from ISON, but not a nucleus. In the video below from the LASCO C2 camera aboard SOHO a headless debris trail can definitely be see heading out from behind the sun. What this debris consists of and whether there are any nuclear remnants in there is unclear. Astronomers are still monitoring, however. Real-time images are available on this website.
UPDATE: 3:56 p.m. EST: Something has emerged from perihelion, but the experts are divided as to whether it’s leftovers of ISON’s tail, or the comet itself. Stay tuned.
Plait and Karl Battams — a Naval Research Laboratory astrophysicist who operates the Sungrazing Comets Project – both participated in a NASA Google+ Hangout on ISON. As of about 2 p.m. EST (7 p.m. UTC), both said that they believe ISON is an “ex-comet”, although it will be a few more hours before scientists can say for sure.
The challenge is that the two spacecraft used to watch ISON swing around the sun — the Solar Dynamics Observatory and SOHO — are not necessarily designed to look for comets. Battams and Plait initially said that it sometimes take additional image processing to view information in it. more As time elapsed though, both expressed extreme skepticism that the comet survived.
Even if the comet is dead, Plait pointed out that scientists can still learn a lot from the remaining debris. ISON is believed to be a pristine example of bodies in the Oort Cloud, a vast body of small objects beyond the orbit of Neptune. Examining the dust in its debris trail could tell scientists more about the origins of the solar system.
UPDATE: 4:40 p.m. EST: On Twitter, the European Space Agency (quoting SOHO scientist Bernhard Fleck) said the comet is gone. Separately, the Naval Research Laboratory’s Karl Battams posted that he thinks recent observations show debris from ISON, but not a nucleus. In the video below from the LASCO C2 camera aboard SOHO a headless debris trail can definitely be see heading out from behind the sun. What this debris consists of and whether there are any nuclear remnants in there is unclear. Astronomers are still monitoring, however. Real-time images are available on this website.
UPDATE: 3:56 p.m. EST: Something has emerged from perihelion, but the experts are divided as to whether it’s leftovers of ISON’s tail, or the comet itself. Stay tuned.
Comet ISON Roasts at Perihelion Passage Today! (November 28, 2013)
Comet ISON is brightening rapidly as it plunges into the sun's atmosphere. At closest approach around 1:45 p.m. EST on Nov. 28th (Thanksgiving Day in the USA), the comet will be little more than a million kilometers above the sun's fiery surface. Temperatures around ISON's icy nucleus could rise as high as 5000o F. No one knows if it can survive that kind of baking--but if it does, it could emerge as a splendid naked-eye comet in early December.
Right now, the best views of the comet are coming from the Solar and Heliospheric Observatory (SOHO). Click to view a 27-hour movie of ISON approaching the sun:
Right now, the best views of the comet are coming from the Solar and Heliospheric Observatory (SOHO). Click to view a 27-hour movie of ISON approaching the sun:
Over the course of the animation, Comet ISON brightens by a factor of at least four, and possibly as much as a factor of 10. It easily outshines the 1st-magnitude red giant star Antares to the lower left of the sun.
Researchers have been wondering what might happen if a CME strikes Comet ISON. They might find out before the day is over. As the movie shows, CMEs are billowing away from the sun in all directions. Avoiding a collision will become increasingly difficult as the comet moves closer to active regions on the sun's surface.
During the hours around closest approach, NASA's Solar Dynamics Observatory (SDO) will take high-resolution pictures of the comet flying through the sun's atmosphere. This diagram illustrates the sequence of events:
Researchers have been wondering what might happen if a CME strikes Comet ISON. They might find out before the day is over. As the movie shows, CMEs are billowing away from the sun in all directions. Avoiding a collision will become increasingly difficult as the comet moves closer to active regions on the sun's surface.
During the hours around closest approach, NASA's Solar Dynamics Observatory (SDO) will take high-resolution pictures of the comet flying through the sun's atmosphere. This diagram illustrates the sequence of events:
Today's close encounter timeline for the Solar Dynamics Observatory's planned activity. CLICK ON THE IMAGE to link to SDO's Live Imagery Centre to watch the encounter in real time!
Usually, SDO points straight at the sun. In this case, however, the observatory is being offset and moved three times to track the speeding comet. SDO images of sungrazing Comet Lovejoy in Dec. 2011 were dramatic. Comet ISON could be even better.
Stay tuned for live images of perihelion (closest approach to the sun) beginning around 12:45 p.m. EST.
Stay tuned for live images of perihelion (closest approach to the sun) beginning around 12:45 p.m. EST.
Waiting For ISON: A Post-Perihelion Viewing Guide (November 27, 2013)
by DAVID DICKINSON, www.universetoday.com
“ISON R.I.P…”
Those are just some of the possible headlines that we’ve wrestled with this week, as Comet C/2012 S1 ISON approaches perihelion tomorrow evening. It’s been a rollercoaster ride of a week, and this sungrazing comet promises to keep us guessing right up until the very end.
Comet ISON reaches perihelion on U.S. Thanksgiving Day Thursday, November 28th at around 18:44 Universal Time/ 1:44 PM Eastern Standard Time. ISON will pass 1.2 million kilometres from the surface of the Sun, just over eight times farther than Comet C/2011 W3 Lovejoy did in 2011, and about 38 times closer to the Sun than Mercury reaches at perihelion.
Those are just some of the possible headlines that we’ve wrestled with this week, as Comet C/2012 S1 ISON approaches perihelion tomorrow evening. It’s been a rollercoaster ride of a week, and this sungrazing comet promises to keep us guessing right up until the very end.
Comet ISON reaches perihelion on U.S. Thanksgiving Day Thursday, November 28th at around 18:44 Universal Time/ 1:44 PM Eastern Standard Time. ISON will pass 1.2 million kilometres from the surface of the Sun, just over eight times farther than Comet C/2011 W3 Lovejoy did in 2011, and about 38 times closer to the Sun than Mercury reaches at perihelion.
Earth-based observers essentially lost sight of ISON in the dawn twilight this past weekend, and there were fears that the comet might’ve disintegrated all together as it was tracked by NASA’s STEREO spacecraft. Troubling reports circulated early this week that emission rates for the comet had dropped while dust production had risen, possibly signaling that fragmentation of the nucleus was imminent. Certainly, this comet is full of surprises, and our observational experience with large sungrazing comets of this sort is pretty meager.
Comet ISON imaged by SOHO LASCO C3 shows THREE tails!!! Now also a very faint and small Sodium tail seem to be present (see detail), while the ion tail is the biggest and the dust tail is clearly positioned along the orbit.
However, as ISON entered the field of view of the Solar and Heliospheric Observatory’s LASCO C3 camera earlier today it still appeared to have some game left in it. NASA’s Solar Dynamics Observatory will pick up ISON starting at around 17:09UT/12:09 PM EST tomorrow, and track it through its history-making perihelion passage for just over two hours until 19:09UT/2:19PM EST.
And just as with Comet Lovejoy a few years ago, all eyes will be glued to the webcast from NASA’s Solar Dynamics Observatory as ISON rounds the bend towards its date with destiny… don’t miss it!
Note: you can also follow ISON’s current progress as seen from SOHO at their website!
And just as with Comet Lovejoy a few years ago, all eyes will be glued to the webcast from NASA’s Solar Dynamics Observatory as ISON rounds the bend towards its date with destiny… don’t miss it!
Note: you can also follow ISON’s current progress as seen from SOHO at their website!
The tracking plan for the Solar Dynamics Observatory on November 28th as ISON passes through perihelion. (Credit: NASA/SDO).
For over the past year since its discovery, pundits have pondered what is now the astronomical question of the approaching hour: just what is ISON going to do post-perihelion? Will it dazzle or fizzle? In this context, ISON has truly become “Schrödinger’s Comet,” both alive and dead in the minds of those who would attempt to divine its fate.
Recent estimates place ISON’s nucleus at between 950 and 1,250 metres in diameter. This is well above the 200 metre size that’s considered the “point of no return” for a comet passing this close to the Sun. But again, another key factor to consider is how well put together the nucleus of the comet is: a lumpy rubble pile may not hold up against the intense heat and the gravitational tug of the Sun!
But what are the current prospects for spotting ISON after its fiery perihelion passage?
If the comet holds together, reasonable estimates put its maximum brightness near perihelion at between magnitudes -3 and -5, in the range of the planet Venus at maximum brilliancy. ISON will, however, only stand 14’ arc minutes from the disk of the Sun (less than half its apparent diameter) at perihelion, and spying it will be a tough feat that should only be attempted by advanced observers.
Note that for observers based at high northern latitudes “north of the 60,” the shallow angle of the ecliptic might just make it possible to spot Comet ISON low in the dawn after perihelion and before sunrise November 29th:
Recent estimates place ISON’s nucleus at between 950 and 1,250 metres in diameter. This is well above the 200 metre size that’s considered the “point of no return” for a comet passing this close to the Sun. But again, another key factor to consider is how well put together the nucleus of the comet is: a lumpy rubble pile may not hold up against the intense heat and the gravitational tug of the Sun!
But what are the current prospects for spotting ISON after its fiery perihelion passage?
If the comet holds together, reasonable estimates put its maximum brightness near perihelion at between magnitudes -3 and -5, in the range of the planet Venus at maximum brilliancy. ISON will, however, only stand 14’ arc minutes from the disk of the Sun (less than half its apparent diameter) at perihelion, and spying it will be a tough feat that should only be attempted by advanced observers.
Note that for observers based at high northern latitudes “north of the 60,” the shallow angle of the ecliptic might just make it possible to spot Comet ISON low in the dawn after perihelion and before sunrise November 29th:
ISON post-perihelion at sunrise on November 29th as seen from Fairbanks, Alaska. (Created using Starry Night Education software.
We’ve managed to see the planet Venus the day of solar conjunction during similar circumstances with the Sun just below the horizon while observing from North Pole, Alaska.
Most northern hemisphere observers may catch first sight of Comet ISON post-perihelion around the morning of December 1st. Look low to the east, about half an hour before local sunrise. Use binoculars to sweep back and forth on your morning comet dawn patrol. Note that on December 1st, Saturn, Mercury, and the slim waning crescent Moon will also perch nearby!
Most northern hemisphere observers may catch first sight of Comet ISON post-perihelion around the morning of December 1st. Look low to the east, about half an hour before local sunrise. Use binoculars to sweep back and forth on your morning comet dawn patrol. Note that on December 1st, Saturn, Mercury, and the slim waning crescent Moon will also perch nearby!
Comet ISON, Mercury, Saturn and the Moon: looking east on the morning of December 1st as seen from latitude 30 degrees north. (Created using Starry Night Education software).
Comet ISON will rapidly gain elevation on successive mornings as it heads off to the northeast, but will also rapidly decrease in brightness as well. If current projections hold, ISON will dip back below magnitude 0 just a few days after perihelion, and back below naked eye visibility by late December. Observers may also be able to start picking it up low to the west at dusk by mid-December, but mornings will be your best bet.
The path of comet ISON for the first week of December as seen from latitude 30 degrees north. Note: the planets and the Moon are depicted for December 1st. (Created using Stellarium).
Keep in mind, if ISON fizzles, this could become a “death-watch” for the remnants of the comet, as fragments that might only be visible with binoculars or a telescope follow its outward path. If this turns out to be the case, then the best views of the “Comet formerly known as ISON” have already occurred.
Another possible scenario is that the comet might fragment right around perihelion, leaving us with a brief but brilliant “headless comet,” similar to W3 Lovejoy back in late 2011. The forward light scattering angle for any comet is key to visibility, and in this aspect, ISON is just on the grim edge in terms of its potential to enter the annals of “great” comets, such as Comet Ikeya-Seki back in 1965.
ISON will then run nearly parallel to the 16 hour line in right ascension from south to north through the month of December as it crosses the celestial equator, headed for a date with the north celestial pole just past New Years Day, 2014.
Whether as fragments or whole, comets have to obey Sir Isaac and his laws of physics as they trace their elliptical path back out of the solar system. Keep in mind, a comet’s dust tail actually precedes it on its way outbound as the solar wind sweeps past, a counter-intuitive but neat concept we may just get to see in action soon.
Here are some key dates to watch for as ISON makes tracks across the northern hemisphere sky. Passages are noted near stars brighter than +5th magnitude and closer than one degree except as mentioned:
Another possible scenario is that the comet might fragment right around perihelion, leaving us with a brief but brilliant “headless comet,” similar to W3 Lovejoy back in late 2011. The forward light scattering angle for any comet is key to visibility, and in this aspect, ISON is just on the grim edge in terms of its potential to enter the annals of “great” comets, such as Comet Ikeya-Seki back in 1965.
ISON will then run nearly parallel to the 16 hour line in right ascension from south to north through the month of December as it crosses the celestial equator, headed for a date with the north celestial pole just past New Years Day, 2014.
Whether as fragments or whole, comets have to obey Sir Isaac and his laws of physics as they trace their elliptical path back out of the solar system. Keep in mind, a comet’s dust tail actually precedes it on its way outbound as the solar wind sweeps past, a counter-intuitive but neat concept we may just get to see in action soon.
Here are some key dates to watch for as ISON makes tracks across the northern hemisphere sky. Passages are noted near stars brighter than +5th magnitude and closer than one degree except as mentioned:
December 1st: ISON is grouped with Saturn, Mercury and the slim crescent Moon in the dawn.
December 2nd: Passes near the +4.9 magnitude star Psi Scorpii.
December 3rd: Passes into the constellation Ophiuchus.
December 5th: Passes near the +2.7 magnitude multiple star Yed Prior.
December 6th: Crosses into the constellation Serpens Caput.
December 8th: Crosses from south to north of the celestial equator.
December 15th: Passes into the constellation Hercules and near the +5th magnitude star Kappa Herculis.
December 17th: The Moon reaches Full, marking the middle of a week with decreased visibility for the comet.
December 19th: Passes into the constellation of Corona Borealis.
December 20th: Passes near the +4.8th magnitude star Xi Coronae Borealis.
December 22nd: Passes 5 degrees from the globular cluster M13. Photo op!
(More to come....)
And after what is (hopefully) a brilliant show, ISON will head back out into the depths of the solar system, perhaps never to return. Whatever the case turns out to be, observations of ISON will have produced some first-rate science… and no planets, popes or prophets will have been harmed in the process. And while those in the business of predicting doom will have moved on to the next apocalypse in 2014, the rest of us will have hopefully witnessed a dazzling spectacle from this icy Oort Cloud visitor, as we await the appearance of the next Great Comet.
Enjoy the show!
December 2nd: Passes near the +4.9 magnitude star Psi Scorpii.
December 3rd: Passes into the constellation Ophiuchus.
December 5th: Passes near the +2.7 magnitude multiple star Yed Prior.
December 6th: Crosses into the constellation Serpens Caput.
December 8th: Crosses from south to north of the celestial equator.
December 15th: Passes into the constellation Hercules and near the +5th magnitude star Kappa Herculis.
December 17th: The Moon reaches Full, marking the middle of a week with decreased visibility for the comet.
December 19th: Passes into the constellation of Corona Borealis.
December 20th: Passes near the +4.8th magnitude star Xi Coronae Borealis.
December 22nd: Passes 5 degrees from the globular cluster M13. Photo op!
(More to come....)
And after what is (hopefully) a brilliant show, ISON will head back out into the depths of the solar system, perhaps never to return. Whatever the case turns out to be, observations of ISON will have produced some first-rate science… and no planets, popes or prophets will have been harmed in the process. And while those in the business of predicting doom will have moved on to the next apocalypse in 2014, the rest of us will have hopefully witnessed a dazzling spectacle from this icy Oort Cloud visitor, as we await the appearance of the next Great Comet.
Enjoy the show!
Is Comet ISON Just “Mostly Dead”?
(November 26, 2013)
by Bob King, astrobob.areavoices.com
Is Comet ISON dying or thriving? There’s much discussion today among amateur and professional astronomers about a decline in its water and dust output and the comet’s reluctance to brighten significantly so close to the sun. I wonder what Miracle Max would have to say?
In one of my favorite movies, “The Princess Bride“, the character Miracle Max (played by Billy Crystal) examines an apparently dead man his friends hope he can bring back to life. Says Max:
“It just so happens that your friend here is only MOSTLY dead. There’s a big difference between mostly dead and all dead. Mostly dead is slightly alive. With all dead, well, with all dead there’s usually only one thing you can do.
Friend: “What’s that?
“Go through his clothes and look for loose change. ”
So maybe ISON is only mostly dead, which as Max points out, is very different from alldead. Like any comet approaching the sun so closely, ISON faces many obstacles: powerful particle winds and solar flares that can shred its tail and rattle the nucleus, tremendous heat and gravitational stress. What a poor 3-kilometer fluffy ball of ice and dust to do? Yes, it might be broken, but even if true, we could still see a spectacular tail after perihelion.
In one of my favorite movies, “The Princess Bride“, the character Miracle Max (played by Billy Crystal) examines an apparently dead man his friends hope he can bring back to life. Says Max:
“It just so happens that your friend here is only MOSTLY dead. There’s a big difference between mostly dead and all dead. Mostly dead is slightly alive. With all dead, well, with all dead there’s usually only one thing you can do.
Friend: “What’s that?
“Go through his clothes and look for loose change. ”
So maybe ISON is only mostly dead, which as Max points out, is very different from alldead. Like any comet approaching the sun so closely, ISON faces many obstacles: powerful particle winds and solar flares that can shred its tail and rattle the nucleus, tremendous heat and gravitational stress. What a poor 3-kilometer fluffy ball of ice and dust to do? Yes, it might be broken, but even if true, we could still see a spectacular tail after perihelion.
Photo of ISON today Nov. 26, 2013 taken by the Cor-B coronagraph on the STEREO Behind spacecraft, the twin of STEREO A. The sun – white circle – is hidden behind a metal disk in an instrument called a coronagraph. Credit: NASA
Pictures taken today by NASA’s STEREO Ahead space probe still show a bright comet head and longish tail. If the nucleus or comet core is cracking up these images are still too low a resolution to tell. On any old day, you wouldn’t know a crisis was brewing.
Now that the comet is too near the sun to see visually the only way we can study it from the ground in the coming days are with radio-dish-style telescopes sensitive to a slice of light between infrared and radio called the submillimeter range. This is where all the bad news is coming from.
Astronomers using the IRAM (Institute for Radio Astronomy in the Millimeter Range) telescope in Spain and James Clerk Maxwell Telescope in Mauna Kea, Hawaii report rapid fading of molecular emission lines (light given off by sunlight-excited molecules sputtering off the nucleus) by a factor of 20 or more. This may indicate that the nucleus is now at best marginally active or that it no longer exists.
Them’s fightin’ words. I’m going to remain guardedly optimistic about ISON’s fate and hope for a little loose change. You can track the comet’s progress through some great resources below:
* Join NASA’s Fire vs. ISON Google+ Hangout LIVE Thursday Nov. 28 from noon-2:30 p.m. CST during perhelion. Listen to and ask questions of professional astronomers and scientist and fab blogger dude Phil Plait.
* Solar Dynamics Observatory views Comet ISON on Nov. 28. This website will display near real-time images and movies of the comet. Images should begin appearing sometime between 11:45 pm and noon CST. The solar space telescope will be specially offset from the sun to shoot the photos.
* Make your own ISON movie using near real-time photos at STEREO/Secchi site. Select the telescope (HI1is or COR-1), click Secchi A for observatory and then punch in the date.
*** Latest update: The International Astronomical Union’s Minor Planet Center has just issued an updated predictions for Comet ISON. A maximum brightness of about first magnitude is forecast at perihelion with the comet entering the morning sky in early December no brighter than magnitude 3.5.
Now that the comet is too near the sun to see visually the only way we can study it from the ground in the coming days are with radio-dish-style telescopes sensitive to a slice of light between infrared and radio called the submillimeter range. This is where all the bad news is coming from.
Astronomers using the IRAM (Institute for Radio Astronomy in the Millimeter Range) telescope in Spain and James Clerk Maxwell Telescope in Mauna Kea, Hawaii report rapid fading of molecular emission lines (light given off by sunlight-excited molecules sputtering off the nucleus) by a factor of 20 or more. This may indicate that the nucleus is now at best marginally active or that it no longer exists.
Them’s fightin’ words. I’m going to remain guardedly optimistic about ISON’s fate and hope for a little loose change. You can track the comet’s progress through some great resources below:
* Join NASA’s Fire vs. ISON Google+ Hangout LIVE Thursday Nov. 28 from noon-2:30 p.m. CST during perhelion. Listen to and ask questions of professional astronomers and scientist and fab blogger dude Phil Plait.
* Solar Dynamics Observatory views Comet ISON on Nov. 28. This website will display near real-time images and movies of the comet. Images should begin appearing sometime between 11:45 pm and noon CST. The solar space telescope will be specially offset from the sun to shoot the photos.
* Make your own ISON movie using near real-time photos at STEREO/Secchi site. Select the telescope (HI1is or COR-1), click Secchi A for observatory and then punch in the date.
*** Latest update: The International Astronomical Union’s Minor Planet Center has just issued an updated predictions for Comet ISON. A maximum brightness of about first magnitude is forecast at perihelion with the comet entering the morning sky in early December no brighter than magnitude 3.5.
Near Earth Asteroid Recorded By Amateur As It Whizzes Past Earth (November 26, 2013)
Earlier today the near-Earth asteroid 2013 NJ sailed by, coming as close as 2.5 lunar distances — about 960,000 km/596,500 miles. That’s a relatively close call, in astronomical terms, but still decidedly a miss (if you hadn’t already noticed.) Which is a good thing since 2013 NJ is estimated to be anywhere from 120–260 meters wide (400-850 feet).
While it’s not all that big among asteroids, even something of that size could have cause a lot of damage if it hadn’t sailed harmlessly past. The meteor that hit Russia earlier this year was only 17-20 meters wide, but it also weighed 13-14,000 tons and injured 1,500 people. An asteroid like 2013 NJ, which is at least six times that size, would cause a lot more damage. So we’re lucky that it kept its distance this time around.
Also unlike the Russian meteor, NASA knew about 2013 NJ and fairly accurately predicted the distance at which it would pass us, so that’s at least comforting—as comforting as anything gets when giant space rocks are flying around your home at several kilometers per second.
We get watch 2013 NJ as it harmlessly passes by in the video above, made from images captured by “shadow chaser” Jonathan Bradshaw from his observatory in Queensland, Australia. Nice work, Jonathan!
Keep tabs on known near-Earth objects on the JPL close pass page here.
While it’s not all that big among asteroids, even something of that size could have cause a lot of damage if it hadn’t sailed harmlessly past. The meteor that hit Russia earlier this year was only 17-20 meters wide, but it also weighed 13-14,000 tons and injured 1,500 people. An asteroid like 2013 NJ, which is at least six times that size, would cause a lot more damage. So we’re lucky that it kept its distance this time around.
Also unlike the Russian meteor, NASA knew about 2013 NJ and fairly accurately predicted the distance at which it would pass us, so that’s at least comforting—as comforting as anything gets when giant space rocks are flying around your home at several kilometers per second.
We get watch 2013 NJ as it harmlessly passes by in the video above, made from images captured by “shadow chaser” Jonathan Bradshaw from his observatory in Queensland, Australia. Nice work, Jonathan!
Keep tabs on known near-Earth objects on the JPL close pass page here.
Comet ISON Breaking Up? (November 25, 2013)
Report from NASA's Comet ISON Observing Campaign (CIOC) website
Comet ISON is currently 19,415,000 km from the Sun and closing fast (at a velocity of 57.15 miles/s or 91.44 km/s). Closest approach: 3 days away!
In our November 23, the overall message was that not much had changed, and the comet appeared to be keeping it all together as it approached the Sun.
That situation may now have changed.
We are seeing reports online that molecular emission from the comet has fallen dramatically, meanwhile dust production seems to be enormous. What this could indicate is that the nucleus has completely disrupted, releasing an enormous volume of dust while significantly reducing emission rates. Fragmentation or disruption of the nucleus has always been the highest risk factor for this comet so if this has indeed happened then while unfortunate, it would not be a surprise.
However, these reports are new, and while they are undoubtedly valid, we do still need to keep observing the comet to be sure what it happening. Remember: Comet ISON is a dynamically new sungrazing comet, fresh in from the Oort Cloud, and the last time we saw an object like this was never! Furthermore, a sungrazing comet just three days from perihelion has never been studied in this kind of detail - we're breaking new ground here! When we factor in your standard "comets are unpredictable" disclaimer, what we have is a huge recipe for the unknown.
Accordingly, we urge observing teams to factor in the changing nature of comet ISON, and attempt to obtain all data they can and share those with us so that we can keep the community informed. We appreciate that observing ISON now is extremely challenging as it is only three days from perihelion. Comet ISON is now very much in the realm of the solar observing fleet, and indeed the NASA STEREO-A spacecraft is returning some amazing views of both comets ISON and Encke.
That situation may now have changed.
We are seeing reports online that molecular emission from the comet has fallen dramatically, meanwhile dust production seems to be enormous. What this could indicate is that the nucleus has completely disrupted, releasing an enormous volume of dust while significantly reducing emission rates. Fragmentation or disruption of the nucleus has always been the highest risk factor for this comet so if this has indeed happened then while unfortunate, it would not be a surprise.
However, these reports are new, and while they are undoubtedly valid, we do still need to keep observing the comet to be sure what it happening. Remember: Comet ISON is a dynamically new sungrazing comet, fresh in from the Oort Cloud, and the last time we saw an object like this was never! Furthermore, a sungrazing comet just three days from perihelion has never been studied in this kind of detail - we're breaking new ground here! When we factor in your standard "comets are unpredictable" disclaimer, what we have is a huge recipe for the unknown.
Accordingly, we urge observing teams to factor in the changing nature of comet ISON, and attempt to obtain all data they can and share those with us so that we can keep the community informed. We appreciate that observing ISON now is extremely challenging as it is only three days from perihelion. Comet ISON is now very much in the realm of the solar observing fleet, and indeed the NASA STEREO-A spacecraft is returning some amazing views of both comets ISON and Encke.
(To keep updated with what the comet is doing, you can check out the CIOC's light-curve which includes new observations from the last two days - see below).
Today's observational data are perhaps a little worrying. Reports of dramatic changes in comet ISON's dust and molecular emission rates may possibly be an indication that the nucleus has disrupted. We may not know for sure until ISON reaches (and hopefully) passes perihelion, though complete disruption - if that is indeed the case - would lead us to think that survival may be unlikely. (Editor's Note: However, it is important to note that this is the first time that we have seen a first time sungrazing comet from the Oort cloud approach perihelion, so we really have nothing with which to compare it. There are others who argue that the significant drop off in molecular emissions may just be a sign that volatiles in areas of the comet nucleus where recent jets have been active may now be exhausted and that this may only be a temporary shutdown, until new pockets of material crack open or that the jet action around the nucleus may have changed its rotational orientation and that new sections of the comet's surface may be now exposed to the intense solar radiation and it may only be a matter of time before it erupts with new activity. These last ideas may be an optimistic stretch, but we are treading on new ground here.) In three days' time, we'll know...
Today's observational data are perhaps a little worrying. Reports of dramatic changes in comet ISON's dust and molecular emission rates may possibly be an indication that the nucleus has disrupted. We may not know for sure until ISON reaches (and hopefully) passes perihelion, though complete disruption - if that is indeed the case - would lead us to think that survival may be unlikely. (Editor's Note: However, it is important to note that this is the first time that we have seen a first time sungrazing comet from the Oort cloud approach perihelion, so we really have nothing with which to compare it. There are others who argue that the significant drop off in molecular emissions may just be a sign that volatiles in areas of the comet nucleus where recent jets have been active may now be exhausted and that this may only be a temporary shutdown, until new pockets of material crack open or that the jet action around the nucleus may have changed its rotational orientation and that new sections of the comet's surface may be now exposed to the intense solar radiation and it may only be a matter of time before it erupts with new activity. These last ideas may be an optimistic stretch, but we are treading on new ground here.) In three days' time, we'll know...
Comet C/2013 R1 Lovejoy Blossoming Too!
(November 25, 2013)
C/2013 R1 Lovejoy has developed a wonderful tail.
While ISON is approaching the Sun in the next few days and is currently invisible, Comet C/2013 Lovejoy is easily observable in the northern hemisphere before the dawn, in the constellation of Canes Venatici,
This picture (6 minutes exposure through a 10mm diameter astrograph), was taken on November 24 at 4:00 UTC. Despite the Moon was very close to it, the comet appears beautiful, showing nice details of its tail.
Being at around 145 million km from the Sun, Lovejoy has just crossed Earth’s orbit. It can be found in the sky under the end of the handle of the "Big Dipper" or "Plow", half way between Eta Ursa Majoris and Alpha Canes Venatici (Cor Caroli). Click here to see its current position on SkyLive.com.
At estimated magnitude of 4.6, amateur Wes Stone of Chiloquin, Oregon reports observing it was a real treat. "Despite moonlight, Lovejoy remains an easy naked-eye object. A tail is obvious in binoculars for about 3 degrees, then fades but can be traced with difficulty for another degree or so. This morning, the tail appeared to be two-branched. The galaxy M63 was visible in the same binocular field.
The coma was slightly bluish with a stellar nucleus, and appeared diffuse on the southern side with the suggestion of a short dust fan. All of these characteristics were more obvious in the telescope."
While ISON is approaching the Sun in the next few days and is currently invisible, Comet C/2013 Lovejoy is easily observable in the northern hemisphere before the dawn, in the constellation of Canes Venatici,
This picture (6 minutes exposure through a 10mm diameter astrograph), was taken on November 24 at 4:00 UTC. Despite the Moon was very close to it, the comet appears beautiful, showing nice details of its tail.
Being at around 145 million km from the Sun, Lovejoy has just crossed Earth’s orbit. It can be found in the sky under the end of the handle of the "Big Dipper" or "Plow", half way between Eta Ursa Majoris and Alpha Canes Venatici (Cor Caroli). Click here to see its current position on SkyLive.com.
At estimated magnitude of 4.6, amateur Wes Stone of Chiloquin, Oregon reports observing it was a real treat. "Despite moonlight, Lovejoy remains an easy naked-eye object. A tail is obvious in binoculars for about 3 degrees, then fades but can be traced with difficulty for another degree or so. This morning, the tail appeared to be two-branched. The galaxy M63 was visible in the same binocular field.
The coma was slightly bluish with a stellar nucleus, and appeared diffuse on the southern side with the suggestion of a short dust fan. All of these characteristics were more obvious in the telescope."
Okay, Well Maybe Today Was the Last Chance to See ISON Before Perihelion
(November 24, 2013)
As Comet ISON approaches the sun, it has become increasingly difficult for observers on Earth to observe or even photograph the comet. My own attempt to spot the comet this morning using binoculars came up short. According to many who have posted tweets or notes on various ISON websites, I am not alone in this unsuccessful hunt. Many comments on these sites suggest that with the increasing light from an approaching moon in the morning sky and the comets ever-shrinking distance from the Sun, the task may now be impossible. But apparently it only seems that way. Working from a high-altitude site in the Canary islands with amazingly clear and steady skies all the way to the horizon, Juan Carlos Casado
successfully imaged Comet ISON on Sunday morning deep inside the rosy glow of dawn:
successfully imaged Comet ISON on Sunday morning deep inside the rosy glow of dawn:
Says Casado, "I took this picture of Comet ISON on Nov. 24th at 6: 25 UT from the Teide Observatory. The comet was over the distant island of Gran Canaria above a sea of clouds about 1 hour before sunrise and only 16° from the sun. The exceptional atmospheric conditions of Teide Observatory allowed me to capture the image."
If the comet does break up at perihelion, there is the possibility that this could this be the last clear photo of Comet ISON taken from Earth. No one knows for sure. Check back tomorrow to see if someone else can pull a rabbit out of his/her hat.
If the comet does break up at perihelion, there is the possibility that this could this be the last clear photo of Comet ISON taken from Earth. No one knows for sure. Check back tomorrow to see if someone else can pull a rabbit out of his/her hat.
Last Chance For Comet ISON...For Now.
(November 23, 2013)
by Bob King, Astrobob.areavoices.com
Truly amazing image of Comet ISON taken Friday Nov. 22 from Austria with an 80mm (3.1″) telescope and two 1-minute exposures. Its tail is exceptionally long but faint. Credit: Michael Jaeger
I tried again this morning to see Comet ISON. Had there been a spotless eastern horizon it might have yielded to my 10×50 binoculars. But as often happens, a little bit of cloud hid the bottom two degrees of sky, so I had to wait till Mercury, Saturn and the hoped-for comet rose into the clear. I looked and looked between 6:10 and 6:35 a.m. at where ISON should have been but saw nothing. Saturn and Mercury were obvious but all else was starless blue where the comet should have been.
Just in case, I took a few photos of the area. We all know the camera sometimes sees more than the eye, but squinting at the LCD display in the warm comfort of home I still can’t see anything. Comet ISON is simply not bright enough now to compete with twilight. Ardent amateurs under exceptional skies may still be able to image the comet the next day or two using motorized tracking cameras and telescopes. You and I? We’re probably up the creek for now.
But hold on tight. After perihelion on Nov. 28, ISON will hopefully return in full regalia with brilliant head and sweeping tail. Use this time to catch up on your sleep – if Act II rises to expectations, we’ll be zombies by Christmas.
Editors Note: If you want to try for one last look for comet ISON before it disappears into the morning glare, use the charts below to have a look on Sunday or Monday morning starting about an hour before sunrise. Good Luck!
Just in case, I took a few photos of the area. We all know the camera sometimes sees more than the eye, but squinting at the LCD display in the warm comfort of home I still can’t see anything. Comet ISON is simply not bright enough now to compete with twilight. Ardent amateurs under exceptional skies may still be able to image the comet the next day or two using motorized tracking cameras and telescopes. You and I? We’re probably up the creek for now.
But hold on tight. After perihelion on Nov. 28, ISON will hopefully return in full regalia with brilliant head and sweeping tail. Use this time to catch up on your sleep – if Act II rises to expectations, we’ll be zombies by Christmas.
Editors Note: If you want to try for one last look for comet ISON before it disappears into the morning glare, use the charts below to have a look on Sunday or Monday morning starting about an hour before sunrise. Good Luck!
Get Out Your Comet Scorecards: Comet Nevski Now Visible With Binoculars
(November 22, 2013)
by DAVID DICKINSON, UNIVERSETODAY.COM
Capture of Comet Nevski shortly after discovery using the ITelescope Observatory in New Mexico. (Credit: Ernesto Guido, Nick Howes & Martino Nicolini).
Is 2013 truly the “Year of the Comet?” Perhaps “Comets” might be a better term, as no less than five comets brighter than +10th magnitude grace the pre-dawn sky for northern hemisphere observers.
Comet C/2013 V3 Nevski has just brightened up 6 magnitudes — just over a 250-fold increase in brightness — and now sits at around magnitude +8.8. Comet Nevski was just recently discovered by Vitali Nevski using a 0.4 metre reflecting telescope two weeks ago on November 8th. If that name sounds familiar, it’s because Nevski discovered the comet from the Kislovodsk observatory located near Kislovodsk, Russia which is part of the International Scientific Optical Network survey which located comet ISON last year. In fact, there was some brief controversy early on in its discovery that Comet C/2012 S1 ISON should have had the moniker Comet Nevski-Novichonok.
At the time of discovery, Comet Nevski appeared to be nothing special: shining at magnitude +15.1, it was well below our +10 magnitude limit for consideration as “interesting,” and was projected to linger there for the duration of its passage through the inner solar system. About a dozen odd such comet discoveries crop up per year, most of which give astronomers a brief pause as the orbit and size of the comet become better known, only to discern that they’re most likely to be nothing extraordinary.
Comet C/2013 V3 Nevski has just brightened up 6 magnitudes — just over a 250-fold increase in brightness — and now sits at around magnitude +8.8. Comet Nevski was just recently discovered by Vitali Nevski using a 0.4 metre reflecting telescope two weeks ago on November 8th. If that name sounds familiar, it’s because Nevski discovered the comet from the Kislovodsk observatory located near Kislovodsk, Russia which is part of the International Scientific Optical Network survey which located comet ISON last year. In fact, there was some brief controversy early on in its discovery that Comet C/2012 S1 ISON should have had the moniker Comet Nevski-Novichonok.
At the time of discovery, Comet Nevski appeared to be nothing special: shining at magnitude +15.1, it was well below our +10 magnitude limit for consideration as “interesting,” and was projected to linger there for the duration of its passage through the inner solar system. About a dozen odd such comet discoveries crop up per year, most of which give astronomers a brief pause as the orbit and size of the comet become better known, only to discern that they’re most likely to be nothing extraordinary.
Such was to be the case with Comet Nevski, until it suddenly flared up this past weekend.
Observer Gianluca Masi caught Comet Nevski in outburst, using a Celestron C14 remotely as part of the Virtual Telescope 2.0 project (see image below).You’ll note that Comet Nevski shows a small, spiky tail on the brief exposure. As of this writing, it currently sits at between magnitudes +8 and +9 and should remain there for the coming week if this current outburst holds.
Comet Nevski is well placed for northern hemisphere observers high in the morning sky, and will spend the remainder of November and early December crossing the astronomical constellation of Leo.
Observer Gianluca Masi caught Comet Nevski in outburst, using a Celestron C14 remotely as part of the Virtual Telescope 2.0 project (see image below).You’ll note that Comet Nevski shows a small, spiky tail on the brief exposure. As of this writing, it currently sits at between magnitudes +8 and +9 and should remain there for the coming week if this current outburst holds.
Comet Nevski is well placed for northern hemisphere observers high in the morning sky, and will spend the remainder of November and early December crossing the astronomical constellation of Leo.
Comet Nevski captured on November 14th by Gianluca Masi. (Credit: The Virtual Telescope 2.0 Project).
Here’s a blow-by-blow rundown on noteworthy events for this comet for the remainder of 2013:
November 23rd: Passes the +5.3 magnitude star Psi Leonis and crosses north of the ecliptic plane.
December 1st: Passes +3.4 magnitude star Eta Leonis.
December 6th: Passes +4.8 magnitude 40 Leonis and the bright +2nd magnitude star Algieba.
December 15th: Crosses into the constellation Leo Minor.
November 23rd: Passes the +5.3 magnitude star Psi Leonis and crosses north of the ecliptic plane.
December 1st: Passes +3.4 magnitude star Eta Leonis.
December 6th: Passes +4.8 magnitude 40 Leonis and the bright +2nd magnitude star Algieba.
December 15th: Crosses into the constellation Leo Minor.
The celestial path of Comet Nevski from mid-November to the end of December. (Created by the author using Starry Night Education simulation software).
December 17th: Passes near the +5.5th magnitude star 40 Leonis Minoris.
December 21st: Passes closest to Earth, at 0.847 Astronomical Units (A.U.s), or 126 million kilometres distant.
December 30th: Passes into the constellation Ursae Majoris.
Note that a “close pass” denotes a passage of the comet within a degree of a bright or interesting object.
The orbit of Comet Nevski is inclined 31.5 degrees relative to the ecliptic, and it will be headed for circumpolar for observers based in high northern latitudes as it dips back down below our “interesting” threshold of magnitude +10 in early 2014.
This comet passed perihelion on October 27th, 2013 just over a week prior to discovery. Comet Nevski is Halley-type comet, with a 27.5 year orbit.
So, looking at the “Comet Scorecard,” we currently have:
Comet C/2012 X1 LINEAR: Still undergoing a moderate outburst at magnitude +8.2, very low to the north east for northern hemisphere observers at dawn in the constellation Boötes.
Comet 2P/Encke: Reached perihelion Nov. 21 at 0.33 AU’s from the Sun, shining at magnitude +7.7 near Mercury in the dawn sky but is now mostly lost in the Sun’s glare.
Comet C/2013 R1 Lovejoy: is currently well placed in the constellation Ursa Major crossing into Canes Venatici in the hours before dawn. Currently shining at magnitude +5.4, Comet R1 Lovejoy is visible to the unaided eye from a dark sky site. We caught sight of the comet last week with binoculars, looking like an unresolved globular cluster as it passed through the constellations of Leo and Leo Minor.
And of course, Comet C/2012 S1 ISON: As of this writing, ISON is performing up to expectations as it approaches Mercury low in the dawn shining at just below +4th magnitude. We’ve seen some stunning pictures as of late as ISON unfurls its tail, and now the eyes of the astronomical community will turn towards the main act: perihelion on November 28th. Will it fizzle or dazzle? More to come next week!
The recent outbursts of Comets X1 LINEAR and V3 Nevski are reminiscent of the major outburst of Comet Holmes back in 2007. Of course, the inevitable attempts to link these outbursts to the current sputtering solar max will ensue, but to our knowledge, no conclusive correlations exist. Remember, the outburst from Comet Holmes occurred as we were approaching what was to become a profound solar minimum.
Also, it might be tempting to imagine that all of these comets are somehow related, but they are in fact each on unique and very different orbits, and only appear in the rough general direction in the sky as seen from our Earthly vantage point… a boon for dawn patrol sky watchers!
December 21st: Passes closest to Earth, at 0.847 Astronomical Units (A.U.s), or 126 million kilometres distant.
December 30th: Passes into the constellation Ursae Majoris.
Note that a “close pass” denotes a passage of the comet within a degree of a bright or interesting object.
The orbit of Comet Nevski is inclined 31.5 degrees relative to the ecliptic, and it will be headed for circumpolar for observers based in high northern latitudes as it dips back down below our “interesting” threshold of magnitude +10 in early 2014.
This comet passed perihelion on October 27th, 2013 just over a week prior to discovery. Comet Nevski is Halley-type comet, with a 27.5 year orbit.
So, looking at the “Comet Scorecard,” we currently have:
Comet C/2012 X1 LINEAR: Still undergoing a moderate outburst at magnitude +8.2, very low to the north east for northern hemisphere observers at dawn in the constellation Boötes.
Comet 2P/Encke: Reached perihelion Nov. 21 at 0.33 AU’s from the Sun, shining at magnitude +7.7 near Mercury in the dawn sky but is now mostly lost in the Sun’s glare.
Comet C/2013 R1 Lovejoy: is currently well placed in the constellation Ursa Major crossing into Canes Venatici in the hours before dawn. Currently shining at magnitude +5.4, Comet R1 Lovejoy is visible to the unaided eye from a dark sky site. We caught sight of the comet last week with binoculars, looking like an unresolved globular cluster as it passed through the constellations of Leo and Leo Minor.
And of course, Comet C/2012 S1 ISON: As of this writing, ISON is performing up to expectations as it approaches Mercury low in the dawn shining at just below +4th magnitude. We’ve seen some stunning pictures as of late as ISON unfurls its tail, and now the eyes of the astronomical community will turn towards the main act: perihelion on November 28th. Will it fizzle or dazzle? More to come next week!
The recent outbursts of Comets X1 LINEAR and V3 Nevski are reminiscent of the major outburst of Comet Holmes back in 2007. Of course, the inevitable attempts to link these outbursts to the current sputtering solar max will ensue, but to our knowledge, no conclusive correlations exist. Remember, the outburst from Comet Holmes occurred as we were approaching what was to become a profound solar minimum.
Also, it might be tempting to imagine that all of these comets are somehow related, but they are in fact each on unique and very different orbits, and only appear in the rough general direction in the sky as seen from our Earthly vantage point… a boon for dawn patrol sky watchers!
Comet ISON in View of Solar Space Observatories (November 22, 2013)
Comet ISON's tail currently maintains a fairly symmetrical and stable shape which seem to indicate a fairly laminar flow of solar wind around the comet (little turbulence) as it closes in on the Sun. However, we need to remember that an image is a snapshot in time. Examine the STEREO Ahead satellite's time lapse movie below to get a clearer perspective of a comet's interaction with the solar wind (at least with comet Encke which is a little closer to the Sun at the moment). Image by Gerald Rhemann on Nov 21 @ Farm Tivoli, Namibia.
As it approaches the sun today at a velocity of over 156,960 mph (251,136 kph), comet ISON apparently remains in one piece. At 33 million miles, the comet has arrived at basically the same distance from the sun as the planet Mercury. The average surface temperature on that planet’s sunny side is 800 degrees F (430 C), so we can begin to appreciate how steamy it must be getting on Comet ISON. All that solar energy vaporizes ice from the comet’s nucleus; light pressure and the solar wind blast dust and gases trapped in the ice back to form a tail.
NASA's twin STEREO probes are designed to observe the sun, however, they can see sundiving comets even when the glare becomes intense. Yesterday, Comet ISON joined Earth, Mercury, and Comet Encke in the field of view of STEREO-A's Heliospheric Imager (see below):
NASA's twin STEREO probes are designed to observe the sun, however, they can see sundiving comets even when the glare becomes intense. Yesterday, Comet ISON joined Earth, Mercury, and Comet Encke in the field of view of STEREO-A's Heliospheric Imager (see below):
"The dark 'clouds' of stuff you see coming from the right are density enhancements in the solar wind, and these are what are causing all the ripples you see in comet Encke's tail," explains Karl Battams of NASA's Comet ISON Observing Campaign. "I can pretty much promise you that we're going to see ISON's tail doing that in a couple of day's time, but on a much larger scale!"
Battams points out another exciting development: Comet Encke and Comet ISON are converging for a photogenic close encounter. "No they're not going to hit each other - in reality they are millions of miles apart - but as seen from the STEREO-A spacecraft, they are going to get very close!" he says. "We are probably a couple of days away from seeing two comets almost side-by-side in that camera, with long tails flowing behind them in the solar wind. To say that such an image will be unprecedented is rather an understatement."
Battams points out another exciting development: Comet Encke and Comet ISON are converging for a photogenic close encounter. "No they're not going to hit each other - in reality they are millions of miles apart - but as seen from the STEREO-A spacecraft, they are going to get very close!" he says. "We are probably a couple of days away from seeing two comets almost side-by-side in that camera, with long tails flowing behind them in the solar wind. To say that such an image will be unprecedented is rather an understatement."
Comet ISON Approaching Mercury
(November 21, 2013)
Comet ISON continues its acceleration towards its November 28th close encounter with the seering outer atmosphere of the sun. Now a week away from that make or break visit, the comet is quickly approaching the planet Mercury both in our skies and in space itself. The comet's co-discoverer, Vitali Nevksy, reported yesterday on Twitter that the comet's nucleus has increased in activity and he estimated the comet's brightness at magnitude +3.7 in the brightening morning sky. Of course the ability for observer's to see the comet and its tail is being hampered this week by the light reflecting off a waning gibbous moon that approaches the comet in the eastern sky with each new day. The next two or three days may be your last chance to see the comet before it disappears completely into the morning twilight (unless it suddenly brightens and becomes visible in daylight - a possibility). Ison will pass Mercury in the morning sky over the next three days.
Note: On Sunday, November 24, right through the new week look toward the low southeastern sky about 30 minutes before sunrise for Mercury and Saturn to pass very close to each other. The ringed world appears the brighter of the two and lower left of Mercury. The next two mornings will see the two planets switch places as Saturn continues to rise and Mercury sinks slowly towards the sun.
Note: On Sunday, November 24, right through the new week look toward the low southeastern sky about 30 minutes before sunrise for Mercury and Saturn to pass very close to each other. The ringed world appears the brighter of the two and lower left of Mercury. The next two mornings will see the two planets switch places as Saturn continues to rise and Mercury sinks slowly towards the sun.
This photo was taken just before dawn on November 21st by Juan Carlos Casado from Teide Observatory (IAC) in Tenerife, Canary Islands. The comet is over the distant island of Gran Canaria, while in the central cloud appears the planet Mercury. The comet is at the limit of naked eye visibility and in the photos appears with a long tail.
New Outburst Brightening Comet ISON
(November 20, 2013)
Yesterday reports on Twitter by amateur astronomers started coming in that the cloud of debris around comet ISON's nucleus (the coma) had brightened significantly and some speculated that the comet may have begun another outburst of fresh volatile materials, similar to the event that happened on November 13/14th. Late yesterday, professional astronomers working with the TRAPPIST telescope at ESO's La Silla Observatory announced that Comet ISON's production of gas and dust surged another six-fold during the early hours of Nov. 19th.
Emmanuel Jehin, astronomer working with the research group, reports, "Since our last report and major outburst on Nov. 14, the ISON production rates were dropping. We lost about a factor 2 in all measured quantities in 4 days. No sign of breakup in the images.The dust features in our pictures seem to be linked to the active regions identified earlier in C2 and CN. But this morning 19.37 Nov UT, we found ISON very active again! All the production rates have been x ~6 since last night, while the AfRho, measuring the quantity of dust, was only x ~2. This looks to us to be the start of a new outburst linked to the active regions, as the jets are today strong again. Our campaign is unfortunately nearly over with TRAPPIST, but we will try to point it again the next couple of nights and confirm this new rise."
A. Maury, JF Soulier and J-G Bosch photographed the head of the comet using a remote 16" RC design telescope and processed the image to bring out details in the inner core on the morning of Nov. 19th:
Emmanuel Jehin, astronomer working with the research group, reports, "Since our last report and major outburst on Nov. 14, the ISON production rates were dropping. We lost about a factor 2 in all measured quantities in 4 days. No sign of breakup in the images.The dust features in our pictures seem to be linked to the active regions identified earlier in C2 and CN. But this morning 19.37 Nov UT, we found ISON very active again! All the production rates have been x ~6 since last night, while the AfRho, measuring the quantity of dust, was only x ~2. This looks to us to be the start of a new outburst linked to the active regions, as the jets are today strong again. Our campaign is unfortunately nearly over with TRAPPIST, but we will try to point it again the next couple of nights and confirm this new rise."
A. Maury, JF Soulier and J-G Bosch photographed the head of the comet using a remote 16" RC design telescope and processed the image to bring out details in the inner core on the morning of Nov. 19th:
Detail of the inner coma and jets are starting to emerge in this image by A. Maury, JF Soulier, and Jean-Gabriel Bosch on Nov 19th.
Experienced observers put the comet's rising magnitude near or brighter than +4.0, well above the threshold of naked-eye visibility. The problem is, ISON is approaching the sun and becoming increasingly difficult to observe.
The situation is only going to worsen as the comet plunges toward its Nov. 28th close encounter with the sun. Amateur photography of the comet will be possible for a few more days and, soon, only NASA's fleet of solar observatories will be able to track the sundiver.
Despite the recent outbursts, which could have been caused by a break up of ISON's nucleus, astronomers with NASA's Comet ISON Observing Campaign believe that the comet is still intact. It will need to be to survive next week's hellish plunge through the sun's atmosphere. If it does survive--a big IF--it could emerge as a splendid naked-eye object for sky watchers in the northern hemisphere.
Observationally speaking, the next big event in the timeline of Comet ISON's journey comes on Nov. 21st when the comet enters the field of view of NASA's STEREO-A spacecraft. The Heliospheric Imager on STEREO-A will pick up the comet just as Earth-bound telescopes begin to lose it. In the days that follow, STEREO-B, SOHO and the Solar Dynamics Observatory will join the hunt, providing continuous views of Comet ISON all the way to perihelion.
The situation is only going to worsen as the comet plunges toward its Nov. 28th close encounter with the sun. Amateur photography of the comet will be possible for a few more days and, soon, only NASA's fleet of solar observatories will be able to track the sundiver.
Despite the recent outbursts, which could have been caused by a break up of ISON's nucleus, astronomers with NASA's Comet ISON Observing Campaign believe that the comet is still intact. It will need to be to survive next week's hellish plunge through the sun's atmosphere. If it does survive--a big IF--it could emerge as a splendid naked-eye object for sky watchers in the northern hemisphere.
Observationally speaking, the next big event in the timeline of Comet ISON's journey comes on Nov. 21st when the comet enters the field of view of NASA's STEREO-A spacecraft. The Heliospheric Imager on STEREO-A will pick up the comet just as Earth-bound telescopes begin to lose it. In the days that follow, STEREO-B, SOHO and the Solar Dynamics Observatory will join the hunt, providing continuous views of Comet ISON all the way to perihelion.
Venus Conjunction with Sigma Sagittari
(November 19, 2013)
When the sun goes down tonight, step outside and look southwest. You can't miss Venus shining brightly through the twilight. Got patience? Keep watching until the sky darkens. Venus is not alone:
"Last night, Venus slid past the star Nunki (Sigma Sagittarii) in the Milk Dipper asterism in Sagittarius," says astronomy professor Jimmy Westlake, who took the picture on November 18th from Stagecoach, Colorado. "The two missed each other by a scant 12.75 arc minutes. Venus (magnitude -4.56) shines a whopping 420 times brighter than Nunki (magnitude +2)." The mismatched pair is separating now, but Venus and Nunki are still only a fraction of a degree apart on Nov. 19th. Take a look!
Leonid Meteor Shower in Progress
(November 19, 2013)
Today, Nov. 19th, Earth is passing through a narrow stream of debris from Comet Tempel-Tuttle, source of the annual Leonid meteor shower. "The Leonids are showing up nicely in our data from the Canadian Meteor Orbit Radar (CMOR)," reports Peter Brown of the University of Western Ontario. "Rates are only about 10 per hour, but the shower is definitely active, if muted due to moonlight this year!"
Astronomers Learning More About the Nuclei of Comet ISON and Lovejoy
(November 18, 2013)
by Bob King, www.universetoday.com
Wonderful photos of Comets ISON and Lovejoy with their swollen comas and developing tails have appeared on these pages, but recently, amateur and professional astronomers have probed deeper to discover fascinating dust structures emanating from their very cores. Most comets possess a fuzzy, starlike pseudo-nucleus glowing near the center of the coma. Hidden within this minute luminous cocoon of haze and gas lies the true comet nucleus, a dark, icy body that typically spans from a few to 10 kilometers wide. Comet ISON’s nucleus could be as large as several kilometers and hefty enough (we hope!) to survive its close call with the sun on Nov. 28.
Sketch using Photoshop of the inner region of Comet Lovejoy’s coma showing the false nucleus and the curious dust fountain observed on Nov. 13 in a 15-inch (37-cm) telescope. Credit: Bob King. At right the same plume photographed on Nov. 12 with north up and east to the left. Credit: Luc Arnold
Last Wednesday morning Nov. 13 when calm air allowed a sharp view inside Comet Lovejoy’s large, 15-arc-minute-wide coma I noticed something odd about the false nucleus at low magnification, so I upped the power to 287x for a closer look. Extending from the fuzzy core in the sunward direction was a small cone or fountain-shaped structure of denser, brighter dust shaped like a miniature comet. It stretched eastward from the center and wrapped slightly to the south. Usually it’s harder than heck to see any details within the fuzzy, low-contrast environment of a comet’s coma unless that comet is close to Earth and actively spewing dust and ice. Lovejoy scored on both.
11/14 Lovejoy’s nucleus and dust fan (negative)
By good fortune, Dr. P. Clay Sherrod of the Arkansas Sky Observatories, USA, and Luc Arnold of Saint-Michel-l’Observatoire, France, shared images they’d made at high magnification of the identical feature right at the same time as my own observation. There’s no doubt that what we saw was a jet or combined jets of dust and vapor blasting from Lovejoy’s true nucleus. Jets are linear or fan-shaped features and carry ice, dust and even snowballs from inside the nucleus out into space. They typically form where freshly-exposed ice from breaks or fissures in the comet’s crust vaporizes in the sun’s heat.
What I wouldn’t give to see one up close. Wait – we can. Take a look at the photo of Comet 103P/Hartley made during NASA’s EPOXI flyby mission in November 2010. Notice that most of Hartley’s crust appears intact with the jets being the main contributors to the dust and gas that form the coma and tail.
What I wouldn’t give to see one up close. Wait – we can. Take a look at the photo of Comet 103P/Hartley made during NASA’s EPOXI flyby mission in November 2010. Notice that most of Hartley’s crust appears intact with the jets being the main contributors to the dust and gas that form the coma and tail.
Multiple jets were actively spewing ice and dust when NASA’s EPOXI mission zoomed by Comet Hartley 2 in November 2010. The fuzzy spots are balls of fluffy snowballs measuring between 1 inch and 1 foot across. Credit: NASA
Spotting a jet usually requires good seeing (low atmospheric turbulence) and high magnification. They’re low-contrast features but worth searching for in any bright comet. Jets often point toward the sun for good reason – the sunward side of the comet is where the heating is happening. Activity dies back as the comet rotates to face away from the sun during the night and early morning hours. By studying the material streaming away from a comet via jets, astronomers can determine the rotation period of the nucleus.
Sometimes material sprayed by jets expands into a curved parabolic hood within the coma. This may explain the wing-shaped structures poking out from Comet ISON’s coma seen in recent photos. Possibly the Nov. 13-14 outburst released a great deal of fresh dust that’s now being pushed back toward the tail by the ever-increasing pressure of sunlight as the comet approaches perihelion.
Sometimes material sprayed by jets expands into a curved parabolic hood within the coma. This may explain the wing-shaped structures poking out from Comet ISON’s coma seen in recent photos. Possibly the Nov. 13-14 outburst released a great deal of fresh dust that’s now being pushed back toward the tail by the ever-increasing pressure of sunlight as the comet approaches perihelion.
Hale-Bopp's spinning nuclear jets
The inner coma of Comet Hale-Bopp developed a striking series of hoods in March 1997 when a dust jet spewed material night after night from the comet’s rotating nucleus. The animation captures garden sprinkler effect beautifully. Since the nucleus spun around every 11 hours 46 minutes, multiple spiraling waves passed through the coma in the sunward direction. To the delight of amateur astronomers at the time, they were plainly visible through the telescope.
Processed images showing a possible jet extending southeast (PA 150 degrees) of Comet ISON’s nucleus as well as the new wing-like hoods on Nov. 17, 2013. Credit: Denis Buczynski and Nick James of the BAA
When examining a comet, I start at low magnification and note coma shape, compactness and color as well as tail form and length and details like the presence of streamers or knots. Then I crank up the power and carefully study the area around the nucleus. Surprises may await your careful gaze. If Comet ISON does break up, the first sign of it happening might be an elongation or stretching of the false nucleus. If it’s no longer a small, star-like disk or if you notice a fainter, second nucleus tailward of the main, the comet’s days may be numbered.
Another view of the symmetrical “wings” photographed branching from Comet ISON’s coma on Nov. 15. At right, the photo has been specially processed to show the structure more clearly. Credit: Erik Bryssinck
Comet ISON's Tail Grows To 7 Degrees!
(November 18, 2013)
by Tony Philips, www.spaceweather.com
Comet's ISON's recent outburst of activity has done more than simply brighten the comet. Whatever exploded from the comet's core also created a spectacularly-long tail, more than 16 million kilometers from end to end. Scroll down to see the full extent of Comet ISON as photographed on Nov. 17th by Michael Jäger of Ebenwaldhöhe, Austria:
Comet ISON's long skinny tail now stretches more than seven degrees across the sky. Image taken by Michael Jäger on November 17, 2013 @ Ebenwaldhöhe, Austria. Photo made with 180mm f4 Apochromat Refractor, Sigma 6303 CCD camera, Exposures: Luminance-4x180 and 2x240 sec.,
RGB 130/130/130 2x2 binned.
"The tail of the comet stretches more than 7o across the sky," says Jäger. It's almost as wide as the bowl of the Big Dipper.
Physically, ISON's tail is about 12 times wider than the sun. So, when the head of ISON plunges into the sun's atmosphere on Nov. 28th, more than 15 million kilometers of the comet's tail will still be jutting into space behind it.
Because so much gas and dust is spewing from the comet's core, it is impossible to see clearly what caused Comet ISON's outburst on Nov. 13-14. One possibility is that fresh veins of ice are opening up in the comet's nucleus, vaporizing furiously as ISON approaches the sun. Another possibility is that the nucleus has completely fragmented.
"If so, it will still be several days before we know for sure," says Karl Battams, an astronomer with NASA's Comet ISON Observing Campaign. "When comet nuclei fall apart, it’s not like a shrapnel-laden explosion. Instead, the chunks slowly drift apart at slightly different speeds. Given that ISON’s nucleus is shrouded in such a tremendous volume of light-scattering dust and gas right now, it will be almost impossible to determine this for at least a few days and perhaps not until the comet reaches the field of view of NASA's STEREO HI-1A instrument on November 21, 2013. We will have to wait for the chunks to drift apart a sufficient distance, assuming they don't crumble first."
Monitoring is encouraged. Comet ISON rises in the east just before the sun. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Dates of special interest include Nov. 17th and 18th when the comet will pass the bright star Spica, making ISON extra-easy to find. Sky maps: Nov. 15, 16, 17, 18,19.
Physically, ISON's tail is about 12 times wider than the sun. So, when the head of ISON plunges into the sun's atmosphere on Nov. 28th, more than 15 million kilometers of the comet's tail will still be jutting into space behind it.
Because so much gas and dust is spewing from the comet's core, it is impossible to see clearly what caused Comet ISON's outburst on Nov. 13-14. One possibility is that fresh veins of ice are opening up in the comet's nucleus, vaporizing furiously as ISON approaches the sun. Another possibility is that the nucleus has completely fragmented.
"If so, it will still be several days before we know for sure," says Karl Battams, an astronomer with NASA's Comet ISON Observing Campaign. "When comet nuclei fall apart, it’s not like a shrapnel-laden explosion. Instead, the chunks slowly drift apart at slightly different speeds. Given that ISON’s nucleus is shrouded in such a tremendous volume of light-scattering dust and gas right now, it will be almost impossible to determine this for at least a few days and perhaps not until the comet reaches the field of view of NASA's STEREO HI-1A instrument on November 21, 2013. We will have to wait for the chunks to drift apart a sufficient distance, assuming they don't crumble first."
Monitoring is encouraged. Comet ISON rises in the east just before the sun. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Dates of special interest include Nov. 17th and 18th when the comet will pass the bright star Spica, making ISON extra-easy to find. Sky maps: Nov. 15, 16, 17, 18,19.
Comet ISON Reports Coming In - Now Naked-Eye Object! (November 16, 2013)by Tony Philips, spaceweather.com
Reports of naked-eye sightings of Comet ISON are coming in from around the world. Experienced observers put the comet's magntitude at +5.5 on Nov. 16th. This means it is now fully 10 times brighter than it was only three days ago before the outburst. To the naked eye, ISON appears as a faint smudge of pale green light low in the pre-dawn sky. The view through a telescope is more dramatic. The comet's tail has become a riotous crowd of gaseous streamers stretching more than 3.5 degrees across the sky. Amateur astronomer Waldemar Skorupa sends this picture from Kahler Asten, Germany:
The tail is so long, he couldn't fit the whole thing in the field of view. How long is it? Comet ISON's tail extends more than 8 million kilometers behind the comet's nucleus. For comparison, that's 21 times the distance between Earth and the Moon.
Because so much gas and dust is spewing from the comet's core, it is impossible to see clearly what caused Comet ISON's outburst on Nov. 13-14. One possibility is that fresh veins of ice are opening up in the comet's nucleus, vaporizing furiously as ISON approaches the sun. Another possibility is that the nucleus has completely fragmented.
"If so, it will still be several days before we know for sure," says Karl Battams, an astronomer with NASA's Comet ISON Observing Campaign. "When comet nuclei fall apart, it’s not like a shrapnel-laden explosion. Instead, the chunks slowly drift apart at slightly different speeds. Given that ISON’s nucleus is shrouded in such a tremendous volume of light-scattering dust and gas right now, it will be almost impossible to determine this for at least a few days and perhaps not until the comet reaches the field of view of NASA's STEREO HI-1A instrument on November 21, 2013. We will have to wait for the chunks to drift apart a sufficient distance, assuming they don't crumble first."
In short, no one knows for sure what is happening to Comet ISON. This could be the comet's death throes--or just the first of many brightening events the comet experiences as it plunges toward the sun for a close encounter on Thanksgiving Day (Nov. 28th).
Because so much gas and dust is spewing from the comet's core, it is impossible to see clearly what caused Comet ISON's outburst on Nov. 13-14. One possibility is that fresh veins of ice are opening up in the comet's nucleus, vaporizing furiously as ISON approaches the sun. Another possibility is that the nucleus has completely fragmented.
"If so, it will still be several days before we know for sure," says Karl Battams, an astronomer with NASA's Comet ISON Observing Campaign. "When comet nuclei fall apart, it’s not like a shrapnel-laden explosion. Instead, the chunks slowly drift apart at slightly different speeds. Given that ISON’s nucleus is shrouded in such a tremendous volume of light-scattering dust and gas right now, it will be almost impossible to determine this for at least a few days and perhaps not until the comet reaches the field of view of NASA's STEREO HI-1A instrument on November 21, 2013. We will have to wait for the chunks to drift apart a sufficient distance, assuming they don't crumble first."
In short, no one knows for sure what is happening to Comet ISON. This could be the comet's death throes--or just the first of many brightening events the comet experiences as it plunges toward the sun for a close encounter on Thanksgiving Day (Nov. 28th).
Comet ISON Showing Lots of Detail, Comet Lovejoy Large and Bright (November 16, 2013)
Comet ISON showing all kinds of interesting detail developing in its dust tail in this image from early this morning (November 16th). Imaged by Michael Jäger on Nov 16 @ Turmkogel, Austria
This morning I had my first real chance to observe comet ISON since its outburst two days ago. Skies were clear at 4AM, so I headed about 40 km west of the city, out to my astronomy club's observatory. There, we have a clear eastern horizon and a place to set up my 8" Schmitt-Cassegrain telescope. With a good set of finder charts, I was able to observe 3 of the comets that I have been reporting on for the last few months: ISON, Lovejoy, and Encke. The attempt to find comet Linear X1 was unsuccessful, in part because it has dimmed substantially from its outburst last week and in part because I wanted to move on to the brighter comets with the limited observing time that was available. Below is an excerpt from my observing notes. I hope your find it interesting and/or helpful as a comparison with your own observations.
"Observed comets ISON, Lovejoy and Encke this morning out at the club observatory! Lovejoy was visible to the naked eye below the back feet of Ursa Major. In 15x70 binoculars Lovejoy was a round smudge brighter to the middle but did not have a truly stellar nucleus. Only a faint hint of a stubby tail. In the 8" SCT at low power it showed an impressiively large coma cloud around the nucleus (8-10x bigger than the fuzzy nucleus) and a faint very short tail which was denser along the center of its long axis and faded off slowly to either side of that line directly behind the head of the comet. Comet ISON was extremely difficult to see naked eye and I'm not sure I was able to spot it, but with the 15x70s it was obvious with a considerable tail! In the 8" SCT at 78X the nucleus of ISON was a star-like point and quite bright. Around it was the coma cloud, fairly uniform in its brightness around and extending away from the nucleus. The coma was much more compacted towards the nucleus than with Lovejoy and smaller (2/3 the size?). ISON's tails were fairly faint but long and beautiful. I say tails because both a thicker dust and pencil thin ion tail were visible. After looking at photos, this may not have been the ion tail but rather a faint separate branch of the dust tail emanating from the coma. At least 3 thin streamers could be seen in the dust tail with averted vision. The 'ion tail' stretched parallel and close to the dust tail behind the head of the comet for perhaps the distance of the 2-3 diameters of the coma. The broader dust tail spreading out in perhaps a 15 degree arc behind the comet stretched quite a ways from the nucleus (perhaps 3/4 to 1 degree). Comet Encke was located fairly close to the planet Mercury (WNW?) and was quite muted in its appearance. Not visible in binoculars, it was spotted in the 8" scope at 67X. Coma was fairly large but washed out with some brightening towards the middle, but nucleus was not distinctive. No tail was evident. Perhaps because I got to it when twilight was starting and the fact that it was low to the horizon made the view less than what I anticipated."
"Observed comets ISON, Lovejoy and Encke this morning out at the club observatory! Lovejoy was visible to the naked eye below the back feet of Ursa Major. In 15x70 binoculars Lovejoy was a round smudge brighter to the middle but did not have a truly stellar nucleus. Only a faint hint of a stubby tail. In the 8" SCT at low power it showed an impressiively large coma cloud around the nucleus (8-10x bigger than the fuzzy nucleus) and a faint very short tail which was denser along the center of its long axis and faded off slowly to either side of that line directly behind the head of the comet. Comet ISON was extremely difficult to see naked eye and I'm not sure I was able to spot it, but with the 15x70s it was obvious with a considerable tail! In the 8" SCT at 78X the nucleus of ISON was a star-like point and quite bright. Around it was the coma cloud, fairly uniform in its brightness around and extending away from the nucleus. The coma was much more compacted towards the nucleus than with Lovejoy and smaller (2/3 the size?). ISON's tails were fairly faint but long and beautiful. I say tails because both a thicker dust and pencil thin ion tail were visible. After looking at photos, this may not have been the ion tail but rather a faint separate branch of the dust tail emanating from the coma. At least 3 thin streamers could be seen in the dust tail with averted vision. The 'ion tail' stretched parallel and close to the dust tail behind the head of the comet for perhaps the distance of the 2-3 diameters of the coma. The broader dust tail spreading out in perhaps a 15 degree arc behind the comet stretched quite a ways from the nucleus (perhaps 3/4 to 1 degree). Comet Encke was located fairly close to the planet Mercury (WNW?) and was quite muted in its appearance. Not visible in binoculars, it was spotted in the 8" scope at 67X. Coma was fairly large but washed out with some brightening towards the middle, but nucleus was not distinctive. No tail was evident. Perhaps because I got to it when twilight was starting and the fact that it was low to the horizon made the view less than what I anticipated."
Comet Lovejoy is easily visible with the unaided eye from dark skies and sports a large coma (head). It is also well placed for northern hemisphere observers, currently traveling just south of the feet of the constellation Ursa Major. Its tail is much smaller than comet ISON's and is much fainter as can be seen in this image by Massimo Russo, Antonella Prvitera, and Michele Surace on November 15, 2013 @ Aspromonte Calabria Italy through a 24" f3.6 telescope.
Comet ISON Brightening Continues
(November 15, 2013)
The abrupt brightening of Comet ISON on Nov. 14th has pushed the comet into the range of naked eye visibility. Dark-sky observers around the world report seeing it with their unaided eyes on the morning of Nov. 15th. To the human eye, ISON is just a faint smudge of magnitude +5.5. Backyard telescopes are revealing much more. The effects of the outburst have propagated into the comet's suddenly riotous tail, as shown in this image taken just hours ago by Jerry Lodriguss of Atsion, New Jersey:
"After its recent outburst, Comet ISON was looking very interesting this morning with multiple streamers in the tail," says Lodriguss.
These changes (the increase in brightness and riotous emergence of gaseous streamers) could be caused by fresh veins of ice opening up in the comet's nucleus. Rapid vaporization of ice by solar heat is a sure-fire way to boost a comet's visibility. But, as NASA's Comet ISON Observing Campaign states, "we have no idea." The comet's nucleus is hidden from view by a hazy green atmosphere, so events in the interior remain a mystery.
"I have a strong suspicion that this is Comet LINEAR (C/1999 S4) all over again," says Mark Kidger of the ESA's European Space Astronomy Centre in Madrid. In the year 2000, Kidger other astronomers monitored Comet LINEAR as it disintegrateden route to the sun. "The sudden appearance of ISON's gas tail, the increasing fuzziness of its coma, and now this sudden outburst all remind me of C/1999 S4 just before it broke apart."
To reiterate: No one knows what is happening to Comet ISON. This could be the comet's death throes--or just the first of many brightening events the comet experiences as it plunges toward the sun for a close encounter on Thanksgiving Day (Nov. 28th).
Monitoring is encouraged. Comet ISON rises in the east just before the sun. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Dates of special interest include Nov. 17th and 18th when the comet will pass the bright star Spica, making ISON extra-easy to find.
These changes (the increase in brightness and riotous emergence of gaseous streamers) could be caused by fresh veins of ice opening up in the comet's nucleus. Rapid vaporization of ice by solar heat is a sure-fire way to boost a comet's visibility. But, as NASA's Comet ISON Observing Campaign states, "we have no idea." The comet's nucleus is hidden from view by a hazy green atmosphere, so events in the interior remain a mystery.
"I have a strong suspicion that this is Comet LINEAR (C/1999 S4) all over again," says Mark Kidger of the ESA's European Space Astronomy Centre in Madrid. In the year 2000, Kidger other astronomers monitored Comet LINEAR as it disintegrateden route to the sun. "The sudden appearance of ISON's gas tail, the increasing fuzziness of its coma, and now this sudden outburst all remind me of C/1999 S4 just before it broke apart."
To reiterate: No one knows what is happening to Comet ISON. This could be the comet's death throes--or just the first of many brightening events the comet experiences as it plunges toward the sun for a close encounter on Thanksgiving Day (Nov. 28th).
Monitoring is encouraged. Comet ISON rises in the east just before the sun. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Dates of special interest include Nov. 17th and 18th when the comet will pass the bright star Spica, making ISON extra-easy to find.
| comets_ison_lovejoy_latenov.pdf |
Comet ISON Brightening Quickly!
(November 14, 2013)
by Bob King, www.universetoday.com
After a sleepy week, Comet ISON is suddenly coming alive. Several amateur astronomers and at least one professional astronomers are reporting today that the comet has brightened at least a full magnitude overnight. Two days ago it glowed at around magnitude 7.5 and was visible weakly in 10×50 binoculars from a dark sky. Now it’s surged to around magnitude 5.5 – just above the naked eye limit – and continues to brighten. Several amateur astronomers have even seen it without optical aid.
Comet ISON in outburst with a completely changed tail appearance and bright, very compact coma shot this morning. Gonzalez reports the comet at magnitude 6.4. Click to enlarge. Credit: Juanjo Gonzalez
ISON’s appearance has radically changed too. A week ago the comet developed a second gas or ion tail streaming alongside the wider, brighter dust tail. That new appendage has since grown like Pinocchio’s nose to nearly equal the length of the dust tail. I spotted it with averted vision Tuesday morning Nov. 12 through a 15-inch (37 cm) telescope. More exciting, the ISON’s head has been much brighter and more compact. Astronomers rate a comet’s degree of condensation or “DC” on a scale of 0 to 9 from extremely diffuse with no brightening in the center to disk-like or stellar. In recent days, Comet ISON has been packing it in at DC=6 or moderately compact and bright. Now amateurs are reporting that the comet’s head has brightened and become much more compact with a DC of 8.
You can watch Comet ISON evolve right before your eyes in this panel of photos taken by Juanjo Gonzalez. Top row left-right: Nov. 3 and Nov. 9. Bottom row left right: Nov. 12 and Nov. 14. The tail structure changes are dramatic. Click to enlarge. Credit: Juanjo Gonzalez
Backing up reports of the outburst, astronomer Emmanuel Jehin of the TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) team, noted a tenfold increase in dust production around the comet’s nucleus on Nov. 11 and 12 plus additional jets of material blasting into the coma. Jehin reports that the inner coma near the nucleus is still very sharp and shows no sign of disruption – so far, ISON’s hanging in there.
If you haven’t seen the comet yet, you can use this map to track it through the weekend as it zips quickly through Virgo. The map shows the sky facing southeast just before the start of morning twilight or about 100 minutes before sunrise. ISON should be plainly visible in binoculars in a dark sky. Created with Chris Marriott’s SkyMap program
This is all great news for comet observers. The intense heat of the sun is beginning to boil away the comet’s ice with greater fury. The heat may also be exposing new cracks or breaks in ISON’s crust. Fresh ice means even more material becomes available for the sun to vaporize and likely additional jumps in brightness in the next day or two.
Amateur Charles Coburn has been photographing comet ISON every clear morning and built a composite image comparing ISON's brightness from Nov. 13th and Nov. 14th. The camera settings were the same. The jump in brightness is obvious.
Leonid Meteor Shower's Roar Somewhat Muted by a Full Moon This Weekend
(November 14, 2013)
Eventhough the Full Moon (occurs on the same day as the peak of the Leonid meteor shower - November 17) will diminish the view, 15 meteors per hour still will radiate from the constellation Leo the Lion.
The Leonid meteor shower, already in progress, will peak with activity this Sunday night although with somewhat fewer 'shooting stars' visible this year due to an interfering Full Moon in the sky. This annual shower is one of the more spectacular ones of the year, active November 6–30 and usually peaking November 17/18 when up to 25-30 meteors per hour are visible. Unfortunately, the Moon becomes Full the morning of the Leonids’ peak. During this phase, it rises around sunset and sets near dawn, so its light will drown out many “shooting stars.” This year, you can expect to see about 15 per hour on average - not bad, given the fact that the bright skies caused by the Moon will wipe out observers' chances of seeing a lot of the dimmer ones.
Your best chance to see some of these vaporizing bits of comet dust is to observe in the hours before dawn. Standing in the shadow of a tree or building to keep the direct light of the Moon from hitting you while you observe should also help, although it will block out some of the sky. It's important to note that it will be possible to see some of them in the nights
leading up to the peak and afterward as well.
Observers may have luck seeing bright fireballs, though, as Leonid meteors hit Earth’s atmosphere at 44 miles per second (71 kilometers per second) and are likely to produce such brilliant streaks.
Your best chance to see some of these vaporizing bits of comet dust is to observe in the hours before dawn. Standing in the shadow of a tree or building to keep the direct light of the Moon from hitting you while you observe should also help, although it will block out some of the sky. It's important to note that it will be possible to see some of them in the nights
leading up to the peak and afterward as well.
Observers may have luck seeing bright fireballs, though, as Leonid meteors hit Earth’s atmosphere at 44 miles per second (71 kilometers per second) and are likely to produce such brilliant streaks.
Image of the 2001 Leonid outburst, when hundreds of meteors were recorded per hour for a short period of time on the peak night of the meteor shower. Note the Beehive Cluster (M44) in the lower right part of the image. Credit: Koen Miskotte
While this year’s show is expected to be anything spectacular, spectacular is what the Leonids are known for — having produced some of the greatest meteor storms of the past three hundred years. In 1966 peak rates reached as high as several thousand meteors a minute, as seen from dark, rural locations — apparently appearing almost like falling rain, by some accounts. It was reported that because of the great number of meteors all appearing to originate from the same portion of the sky that many observers felt like they had to grip the ground to avoid falling over — with the Earth apparently appearing to be plowing through space at a great speed (as it is), rather than appearing stationary as it typically does to human perception.
Other major outbursts of this shower have also happened in 1999, 2001 and 2002 due to an influx of new material from streamers of debris left by comet Temple-Tuttle, the source of the meteor particles as it passed a short time earlier on its 33 years orbit. However, these outbursts are rare and chances of Earth encountering a particularly thick stream of debris this year are calculated to be very low.
Other major outbursts of this shower have also happened in 1999, 2001 and 2002 due to an influx of new material from streamers of debris left by comet Temple-Tuttle, the source of the meteor particles as it passed a short time earlier on its 33 years orbit. However, these outbursts are rare and chances of Earth encountering a particularly thick stream of debris this year are calculated to be very low.
Comet to Bring Next New Meteor Shower
(November 13, 2013)
by John Bochanski, SkyandTelescope.com
Astronomers confirm that debris from Comet 209P/ LINEAR should create a sky show on May 24, 2014.
This long exposure image of the intense 2002 Leonid meteor shower could give us a preview of what to expect with this new meteor shower in 2014. Image from Jerry Garrett.
Most meteor showers, like this week’s Leonids, occur when Earth plows into the debris trail left behind by a comet. The comet throws this debris off as it’s heated by the Sun, but while all comets heat up as they enter the inner solar system, many do not have orbits that intersect with Earth’s. That’s why the number of major meteor showers per year has remained relatively constant, even though we’re regularly discovering new comets.
The tried-and-true list of showers might change soon, though. As we noted in 2012, the comet 209P/LINEAR, which passed by the Sun in 2009, may produce a big meteor shower on May 24, 2014. New calculations by Quanzhi Ye and Paul A. Wiegert (both University of Western Ontario) refine that prediction — and make it a little less optimistic.
The tried-and-true list of showers might change soon, though. As we noted in 2012, the comet 209P/LINEAR, which passed by the Sun in 2009, may produce a big meteor shower on May 24, 2014. New calculations by Quanzhi Ye and Paul A. Wiegert (both University of Western Ontario) refine that prediction — and make it a little less optimistic.
According to predictions, a little-known comet will pass perihelion in early May of 2014 and, two weeks later, sandblast Earth with dust particles spread along its orbit.
NASA / JPL / Horizons
Comet 209P/LINEAR was discovered in 2004 by an automated observing campaign. With a period of just over 5 years, the comet stays relatively close to the Sun and inner solar system. Detailed calculations of its orbit indicated that in May 2014 the comet’s debris trails would pass extremely close to Earth (about 0.0002 Earth-Sun distances, or within spitting distance of our planet’s outermost atmosphere). These thousands of particles could burn up in Earth’s atmosphere as meteors when our planet plows through the debris field.
Ye and Wiegert used images from the comet’s last visit in late 2008 and 2009 to model the comet’s trajectory and predict what kind of shower its crumbs might create. The shower’s strength depends on the size of debris particles left behind. Although astronomers can’t go out with a net and collect the particles for measurement, they can find this information encoded in the curve of the comet’s grand dust tail. The curve’s shape depends on the interplay between the radiation pressure and gravity of the Sun, and different sized particles will produce tails with different amounts of curvature.
Ye and Wiegert used images from the comet’s last visit in late 2008 and 2009 to model the comet’s trajectory and predict what kind of shower its crumbs might create. The shower’s strength depends on the size of debris particles left behind. Although astronomers can’t go out with a net and collect the particles for measurement, they can find this information encoded in the curve of the comet’s grand dust tail. The curve’s shape depends on the interplay between the radiation pressure and gravity of the Sun, and different sized particles will produce tails with different amounts of curvature.
This perspective shows the hemisphere of Earth that will be facing the incoming dust particles from Comet 209P/LINEAR when the activity peaks on May 24, 2014. Skywatchers in southern Canada and the continental U.S. will be especially well positioned to watch the sky show.
Mikhail Maslov
As Ye and Wiegert report in an upcoming Monthly Notices of the Royal Astronomical Society, the team’s calculations suggest that the comet has been producing relatively large particles (on the order of 1 mm), meaning that the upcoming meteor shower may be chock-full of bright meteors. But their work also places limits on the overall rate of meteors, suggesting a rate of 200 per hour under ideal conditions.
That’s in the same ballpark as previous, independent work by Jérémie Vaubaillon (IMCEE, France) and Mikhail Maslov: Maslov, for example, estimated between 100 and 400 meteors per hour. But Ye and Wiegert warn that, “given the current relatively weak dust production of the comet, rates could be much lower.” With the low dust production, as well as the team’s lower estimate of how many debris streams from the comet's previous passes are hanging around in this region of space, it’s highly unlikely that we’re in for a “meteor storm” (1,000 per hour) — although the team couldn’t quite rule it out.
Whatever the outcome, it’ll be worth going out to look in May. The meteor shower is set to peak around 7h Universal Time on May 24, 2014, with the radiant point (where the meteors appear to come from) in the constellation Camelopardalis. That’ll be a fist-width or two above the horizon for those around latitude 40° N; the shower should be easily visible from much of the Northern Hemisphere.
As Comet 209P/LINEAR enters the inner solar system again, it will brighten but still be relatively faint with an apparent magnitude of 11 around the time of the shower. Nonetheless, skywatchers will have their telescopes trained on this comet, as new data on its position and brightness will be crucial for updating models of its behavior. I know I will be looking up as well, searching for meteors in the early spring sky.
That’s in the same ballpark as previous, independent work by Jérémie Vaubaillon (IMCEE, France) and Mikhail Maslov: Maslov, for example, estimated between 100 and 400 meteors per hour. But Ye and Wiegert warn that, “given the current relatively weak dust production of the comet, rates could be much lower.” With the low dust production, as well as the team’s lower estimate of how many debris streams from the comet's previous passes are hanging around in this region of space, it’s highly unlikely that we’re in for a “meteor storm” (1,000 per hour) — although the team couldn’t quite rule it out.
Whatever the outcome, it’ll be worth going out to look in May. The meteor shower is set to peak around 7h Universal Time on May 24, 2014, with the radiant point (where the meteors appear to come from) in the constellation Camelopardalis. That’ll be a fist-width or two above the horizon for those around latitude 40° N; the shower should be easily visible from much of the Northern Hemisphere.
As Comet 209P/LINEAR enters the inner solar system again, it will brighten but still be relatively faint with an apparent magnitude of 11 around the time of the shower. Nonetheless, skywatchers will have their telescopes trained on this comet, as new data on its position and brightness will be crucial for updating models of its behavior. I know I will be looking up as well, searching for meteors in the early spring sky.
New Amateur Video of Comets Lovejoy and ISON (November 13, 2013)
Comet 2012 S1 (ISON) is just 16 days away from its close encounter with the Sun and is now inside the orbit of Venus, at under 103,000,000 km (64,000,000 miles) away from the Sun. This new timelapse by award-winning photographer Justin Ng from Singapore shows the journey of both ISON and Comet 2013 R1 (Lovejoy), taken on November 11, 2013. The video covers 50 minutes of imaging time for ISON and 90 minutes of imaging time for Lovejoy.
As you watch the video of each, don’t worry – the comets and their tails are not fizzling out! This actually reflects the reduced visibility of the comets as the sky was gradually becoming brighter with daybreak. Additionally, Justin cautions that in the timelapse, both comets appear to be moving especially fast because of smaller field of view and long exposure.
As you watch the video of each, don’t worry – the comets and their tails are not fizzling out! This actually reflects the reduced visibility of the comets as the sky was gradually becoming brighter with daybreak. Additionally, Justin cautions that in the timelapse, both comets appear to be moving especially fast because of smaller field of view and long exposure.
On November 4, there were indications of a possible ion tail emerging from Comet ISON, and this comet’s growing dust tail now stretches to more than a full moon’s diameter. “Comet ISON is now plunging towards the Sun with 2 long tails at a magnitude of around +7 and it is visible in small scopes and strong binoculars,” writes Justin.
Comet ISON flies in front of constellation Virgo this week (from our vantage point on Earth) and it is expected to grow some 2.5 times brighter before it passes by the bright star Spica in Virgo on November 17 and 18.
“Comet Lovejoy just passed into the constellation Leo with a magnitude of around +6 and it’s an easy binocular object,” said Justin. “R1 Lovejoy will remain well placed at 50 to 60 degrees above the northeastern horizon before sunrise through this week for observers from near the Equator.”
Comet ISON flies in front of constellation Virgo this week (from our vantage point on Earth) and it is expected to grow some 2.5 times brighter before it passes by the bright star Spica in Virgo on November 17 and 18.
“Comet Lovejoy just passed into the constellation Leo with a magnitude of around +6 and it’s an easy binocular object,” said Justin. “R1 Lovejoy will remain well placed at 50 to 60 degrees above the northeastern horizon before sunrise through this week for observers from near the Equator.”
This beautifully detailed image of comet Lovejoy was taken November 12, 2013 by Rolando Ligustri. Note the streamers in the tail and how they have changed since last week (compare to images farther down this page).
Weird Dog Bone Asteroid Closest to Earth Tonight (November 12, 2013)
Asteroid 216 Kleopatra is one weird main belt asteroid. First of all, it looks more like a dog bone than an asteroid. It even looks more like a dog bone than any real dog bone I've ever seen. And its big! Measuring 217 × 94 × 81 km, it has been interesting to astronomers since it's discovery back in 1880 because of its highly variable brightness. Given its weird shape, orientation to Earth and a 5.4 hour rotation period we now know why it changes brightness so quickly. But the asteroid has revealed much more about itself to astronomers over the last decade.
In 1993, a search for moons using Hubble's Wide Field Planetary Camera (the first of Hubble's cameras) came up empty, but Kleopatra was far (2.38 AU) from Earth at the time. There was a particularly good opposition late in 2008, when Kleopatra was only 1.23 AU from Earth, and that's when the two moons were discovered and their motions observed using the adaptive optics-equipped Keck II telescope. Here's one of the images from Keck II showing the newly discovered moons, which also actually resolves the asteroid as a dog-bone shape:
In 1993, a search for moons using Hubble's Wide Field Planetary Camera (the first of Hubble's cameras) came up empty, but Kleopatra was far (2.38 AU) from Earth at the time. There was a particularly good opposition late in 2008, when Kleopatra was only 1.23 AU from Earth, and that's when the two moons were discovered and their motions observed using the adaptive optics-equipped Keck II telescope. Here's one of the images from Keck II showing the newly discovered moons, which also actually resolves the asteroid as a dog-bone shape:
Kleopatra and its two moons, outer Alexhelios (1) and inner Cleoselene (2). The two moons are about 9 and 7 kilometers in diameter and orbit 454 and 678 kilometers away from Kleopatra. Image by Franck Marchis.
The outer and inner satellites, named Alexhelios and Cleoselene respectively, are about 9 km and 7 km in diameter and named after Egyptian Cleopatra's children Alexander Helios and Cleopatra Selene II. Alexhelios takes 2.3 days to orbit its parent while Cleoselene takes 1.24 days.
Frank Marchis, leader of the discovery team provides an animation of the orbits of these satellites around their parent body:
Frank Marchis, leader of the discovery team provides an animation of the orbits of these satellites around their parent body:
The discovery of satellites made (216) Kleopatra the fourth discovered triple asteroid in the Main Belt, after (87) Sylvia, (45) Eugenia, and (3749) Balam.
Impact Event Changed Everything
Calculations from its radar albedo and the orbits of its moons show 216 Kleopatra to be a rubble pile, a loose amalgam of metal, rock, and 30–50% empty space by volume, likely due to a disruptive impact prior to the impact that created its moons.
The impact (likely oblique in nature) is theorized to have happened about 100 million years ago and is also responsible for Kleopatra's shape, rotation, and moons. The increased rotation would have elongated the asteroid and caused Alexhelios to split off. Cleoselene may have split off later, around 10 million years ago. Kleopatra is a contact binary - if it were spinning much faster, the two lobes would separate from each other, making a true binary system.
Where to Look
216 Kleopatra is currently residing in the southern region of the constellation Taurus, the Bull, making it visible throughout November's chilly nights. Because it is at its closest to earth and near its perihelion position (nearest the sun) the asteroid shines at its brightest this week, visible at about magnitude +9.5, making it a binocular object from suburban skies. Perhaps now is the time to go dig up that old dog bone in your backyard!
Impact Event Changed Everything
Calculations from its radar albedo and the orbits of its moons show 216 Kleopatra to be a rubble pile, a loose amalgam of metal, rock, and 30–50% empty space by volume, likely due to a disruptive impact prior to the impact that created its moons.
The impact (likely oblique in nature) is theorized to have happened about 100 million years ago and is also responsible for Kleopatra's shape, rotation, and moons. The increased rotation would have elongated the asteroid and caused Alexhelios to split off. Cleoselene may have split off later, around 10 million years ago. Kleopatra is a contact binary - if it were spinning much faster, the two lobes would separate from each other, making a true binary system.
Where to Look
216 Kleopatra is currently residing in the southern region of the constellation Taurus, the Bull, making it visible throughout November's chilly nights. Because it is at its closest to earth and near its perihelion position (nearest the sun) the asteroid shines at its brightest this week, visible at about magnitude +9.5, making it a binocular object from suburban skies. Perhaps now is the time to go dig up that old dog bone in your backyard!
Coarse finder chart - (Field of view=60°, Limiting magnitude=6.5)
Courtesty of Heavens-Above.com
Fine finder chart
(Field of view=2°, Limiting magnitude=12) Image courtesy of Heavens-Above.com
Seeing Double: Comet ISON Grows a Second Tail (November 12, 2013)
Comet ISON is beginning to reveal more and more of itself to amateur observers as it accelerates toward the sun for a Nov. 28th close encounter with the sun's searing outer layers. As the heat continues to rise, the comet is brightening, now revealing new features in its tail every day. The long exposure composite colour image above, taken by Michael Jäger of Jauerling Austria on the night of Nov. 10th, shows how the comet has developed a beautiful delicate double tail.
The lower fainter tail in the image is the ion tail. It is a thin streamer of ionized gas pushed away from the comet by solar wind. The filamentary ion tail points almost directly away from the sun.
The upper brighter and broader tail is the dust tail. Like Hansel and Gretel leaving bread crumbs to mark their way through the forest, ISON is leaving a trail of comet dust as it moves through the solar system. Compared to the lightweight molecules in the ion tail, grains of comet dust are heavier and harder for solar wind to push around. The dust tends to stay where it is dropped. The dust tail, therefore, traces the comet's orbit and does not point directly away from the sun as the ion tail does.
Comet ISON is currently moving through the constellation Virgo low in the eastern sky before dawn. Shining like an 8th magnitude star, it is still too dim for naked eye viewing, but an increasingly easy target for backyard optics. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Special dates of interest are Nov. 17th and 18th when the comet will pass to the south and west of the bright star Spica. Below is a finder chart for the comet with comet Encke and the planet Mercury (now visible) also plotted for today and tomorrow. Website spaceweather.com offers the following sky maps:Nov. 10, 11, 12, 13, 14, 15, 16, 17, 18, 19.
The lower fainter tail in the image is the ion tail. It is a thin streamer of ionized gas pushed away from the comet by solar wind. The filamentary ion tail points almost directly away from the sun.
The upper brighter and broader tail is the dust tail. Like Hansel and Gretel leaving bread crumbs to mark their way through the forest, ISON is leaving a trail of comet dust as it moves through the solar system. Compared to the lightweight molecules in the ion tail, grains of comet dust are heavier and harder for solar wind to push around. The dust tends to stay where it is dropped. The dust tail, therefore, traces the comet's orbit and does not point directly away from the sun as the ion tail does.
Comet ISON is currently moving through the constellation Virgo low in the eastern sky before dawn. Shining like an 8th magnitude star, it is still too dim for naked eye viewing, but an increasingly easy target for backyard optics. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Special dates of interest are Nov. 17th and 18th when the comet will pass to the south and west of the bright star Spica. Below is a finder chart for the comet with comet Encke and the planet Mercury (now visible) also plotted for today and tomorrow. Website spaceweather.com offers the following sky maps:Nov. 10, 11, 12, 13, 14, 15, 16, 17, 18, 19.
Mercury is now visible low in the southeastern sky below Virgo’s brightest star Spica. The planet will rise higher in the coming days and get easier to see. To find it, sweep the area to the lower left of Spica 5-10 degrees above the horizon with binoculars. This map shows the sky about 50 minutes before sunrise facing southeast. Image created with Stellarium.
Of Comets, Meteors and Jovian Shadows...
(November 11, 2013)
The solar system is a dynamic happening kind of place and the skies above us over the next few nights remind us of that with a flurry of events for us to observe and experience. Here are a few highlights:
1) Comet Lovejoy and Others in the Early Morning Sky
Four comets are currently on display for binoculars or small telescopes in the east before the beginning of dawn (for Northern Hemisphere observers). One is Comet ISON, still under-performing (but nice) at only about 8th magnitude. It starts this week about midway between Mars and Spica and speeds toward Spica daily, to pass it on November 17th and 18th.
1) Comet Lovejoy and Others in the Early Morning Sky
Four comets are currently on display for binoculars or small telescopes in the east before the beginning of dawn (for Northern Hemisphere observers). One is Comet ISON, still under-performing (but nice) at only about 8th magnitude. It starts this week about midway between Mars and Spica and speeds toward Spica daily, to pass it on November 17th and 18th.
Pictured from left to right are exploding Comet LINEAR X1, sungrazing Comet ISON, short-period Comet Encke, and the brightest of them all, Comet Lovejoy. All four are visible in binoculars or backyard telescopes, and Comet Lovejoy (mag. +6.0) is visible to the naked eye from dark-sky sites. Comet ISON is actually one of the faintest of the group; only expanding Comet LINEAR X1 (mag. +8) is more difficult to see.
But ISON is being outdone! Comet 2013 R1 (Lovejoy) "is a humdinger — almost as bright now as Comet ISON was forecast to be," writes SkyandTelescope.com's Tony Flanders. "And it's very high in the sky... big, bright, and beautiful in 10×30 binoculars."
The other two comets, Encke and C/2012 X1 (LINEAR), are fainter. See articles below on this page or Tony's S&T article The Other Great Morning Comet, for finder charts for Lovejoy and ISON and the others. Further details and charts for all four are also available at comets.skyhound.com.
Don't procrastinate on this! Encke is getting very low, and moonlight returns to the just-before-dawn sky after about November 15th. Other dates of special interest include Nov. 15-18 when Comet LINEAR X1 passes by the bright star Arcturus, Nov 17-18 when Comet ISON has a close encounter with Spica, and Nov. 18-20 when Comet Encke buzzes Mercury. These stars and planets make excellent naked-eye guideposts for finding the comets. Meanwhile, bright Comet Lovejoy is approaching the Big Dipper; if you can't see it with your unaided eye, a quick scan with binoculars will reveal it.
The other two comets, Encke and C/2012 X1 (LINEAR), are fainter. See articles below on this page or Tony's S&T article The Other Great Morning Comet, for finder charts for Lovejoy and ISON and the others. Further details and charts for all four are also available at comets.skyhound.com.
Don't procrastinate on this! Encke is getting very low, and moonlight returns to the just-before-dawn sky after about November 15th. Other dates of special interest include Nov. 15-18 when Comet LINEAR X1 passes by the bright star Arcturus, Nov 17-18 when Comet ISON has a close encounter with Spica, and Nov. 18-20 when Comet Encke buzzes Mercury. These stars and planets make excellent naked-eye guideposts for finding the comets. Meanwhile, bright Comet Lovejoy is approaching the Big Dipper; if you can't see it with your unaided eye, a quick scan with binoculars will reveal it.
Comet Lovejoy taken by Michael Jäger on November 10, 2013 @ Jauerling Austria. Note the fine tail structure!
2) Northern Taurid Meteor Shower Peaks Tuesday Night, November 11th
Observers braving the cold may want to keep in mind that the Northern branch of the Taurid Meteor Shower is peaking in activity on the night of Nov. 11/12th (see news article below on this page). This shower has a relatively low hourly rate of 5-10 shooting stars but has been known to produce some brilliant fireballs each year. Best observing times are after the moon moves low into the west in the early morning hours. Comet watchers take note!
Observers braving the cold may want to keep in mind that the Northern branch of the Taurid Meteor Shower is peaking in activity on the night of Nov. 11/12th (see news article below on this page). This shower has a relatively low hourly rate of 5-10 shooting stars but has been known to produce some brilliant fireballs each year. Best observing times are after the moon moves low into the west in the early morning hours. Comet watchers take note!
3) Double Shadow Transit of Jovian Satellites on Tuesday November 12th
In case you can't get up early for these events, the planet Jupiter is offering up a double shadow transit on Tuesday night (actually commencing at 03:00 UT - on Wednesday morning) involving the moons Io and Europa. Io's shadow first crosses on to the Jovian disk at 00:58 UT (7:58 PM EST) followed about an hour later by the transit ingress of the satellite itself. At 3:00 UT (11:00 PM EST), Europa's shadow starts it's journey across the disk and for the next 14 minutes both shadows will work their way along until Io's shadow departs at 3:14 UT (11:14 PM EST).
In case you can't get up early for these events, the planet Jupiter is offering up a double shadow transit on Tuesday night (actually commencing at 03:00 UT - on Wednesday morning) involving the moons Io and Europa. Io's shadow first crosses on to the Jovian disk at 00:58 UT (7:58 PM EST) followed about an hour later by the transit ingress of the satellite itself. At 3:00 UT (11:00 PM EST), Europa's shadow starts it's journey across the disk and for the next 14 minutes both shadows will work their way along until Io's shadow departs at 3:14 UT (11:14 PM EST).
Comet ISON Now a Binocular Object!
(November 9, 2013)
Comet ISON is brightening as it approaches the sun. Multiple observers now report that it is a binocular object. "I finally saw Comet ISON for the first time using small binoculars!" says pilot Brian Whittaker. He was flying 38,000 feet over the Mediterranean Sea on Nov. 8th when he took this picture showing where to look:
"It was faint, but is predicted to brighten and move each day," he adds. "Exciting! "
"I have made my first confirmed binocular sighting of C/2012 S1 ISON as well," reports Pete Lawrence of Selsey UK on Nov. 9th. "ISON's head appears small and stellar through a pair of 15x70s optics."
Comet ISON is currently moving through the constellation Virgo low in the eastern sky before dawn. Shining like an 8th magnitude star, it is still too dim for naked eye viewing, but an increasingly easy target for backyard optics. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Special dates of interest are Nov. 17th and 18th when the comet will pass the bright star Spica. Sky maps: Nov. 10, 11, 12, 13, 14, 15, 16, 17, 18, 19.
Don't delay, because Comet ISON is plunging toward the sun for a perilous encounter on Nov. 28th. At closest approach, the comet will be deep inside the sun's corona and little more than a million kilometers from the fiery stellar surface. If ISON survives--a big IF--it could emerge from solar fire as a naked-eye comet for northern-hemisphere observers in December.
Monitoring is encouraged!
"I have made my first confirmed binocular sighting of C/2012 S1 ISON as well," reports Pete Lawrence of Selsey UK on Nov. 9th. "ISON's head appears small and stellar through a pair of 15x70s optics."
Comet ISON is currently moving through the constellation Virgo low in the eastern sky before dawn. Shining like an 8th magnitude star, it is still too dim for naked eye viewing, but an increasingly easy target for backyard optics. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Special dates of interest are Nov. 17th and 18th when the comet will pass the bright star Spica. Sky maps: Nov. 10, 11, 12, 13, 14, 15, 16, 17, 18, 19.
Don't delay, because Comet ISON is plunging toward the sun for a perilous encounter on Nov. 28th. At closest approach, the comet will be deep inside the sun's corona and little more than a million kilometers from the fiery stellar surface. If ISON survives--a big IF--it could emerge from solar fire as a naked-eye comet for northern-hemisphere observers in December.
Monitoring is encouraged!
A Pair of Double Stars Worth Observing
(November 9, 2013)
While the waxing and waning moon often interferes with observer's attempts to hunt down diffuse and/or dim objects far beyond the boundaries of our solar system, the stars themselves often offer interesting targets for our perusal. Stars with one or more stellar companions, in fact, provide neat little jewels of colour, brightness and pattern that are virtually immune to the background brightening effects of a crescent or gibbous moon. Here are a couple of my favourite autumn double stars for your consideration:
1) Alpha Piscium (ALRESCHA) SAO 110291
1) Alpha Piscium (ALRESCHA) SAO 110291
Located at the bottom of the "V" configuration in the constellation Pisces, the fish, Alpha Piscium is visible to the naked eye even from fairly light polluted locations if you know where to look. This 4th magnitude point of light is well above the eastern horizon a half hour after sunset. Because the A and B components of this binary pair have magnitudes of +4.3 and +5.2 and are separated by only 1.8 arc seconds, this binary system is considered a challenge for small telescopes because it hovers right around the resolution limit from these scopes. Depending on seeing conditions, a telescope with a 70mm aperture might be tested, however any scope with an aperture of 100mm or larger should find splitting this pair much easier. To make things easier, use a magnification of 150x - 200x on a night when the air is steady. The stars are both spectral A-class dwarfs and should appear white or bluish-white. Some observers report a greenish tint, perhaps a consequence of close pairing and optical effects. The fainter secondary lies at a position angle of 269 degrees - nearly due west - from the primary and has an orbital period of 933 years. Periastron (when the pair will be closest together) will occur in 2060. The system is 139 light years away.
The circle above the eastern horizon indicates the location of Alpha Piscium shortly after twilight ends. Imaged with Stellarium.
2) Eta Persei (Miram) SAO 23655, 15 Persei
Located at the head of the constellation Perseus, the warrior, Eta Persei is a great large binocular double star with a dazzling difference in colours and brightness between the primary and secondary stars. In reality, the stellar system is actually composed of SIX stars, all of which can be seen with moderate-sized telescopes under dark-sky conditions (see image above). For most observers with small telescopes, the brightest pair of stars, the A and B components, are fascinating enough, shining at magnitudes +3.8 and +8.5 respectively. Various observers have described the colour of the primary star as anything from "golden yellow" to 'crimson red". Most agree it is somewhere in between - call it a burnt orange. The dimmer secondary star, component B, is more commonly described as a blue or bluish white, although some observers have even called it a "cobalt blue". See what you think. What ever the case, the colour contrast between these two is striking.
The primary star, component A, is actually an orange giant star with an M3 spectral type. At 875 light years away, it is the 388th brightest star in the Earth's sky and its iron abundance +0.04 (109.6% of the Sun). It is moving through the Galaxy at a speed of 29.1 km/s relative to the Sun. The spectal type of the B component has been difficult to pin down but appears to classify this star as an A-type main sequence dwarf. The two are separated in the sky by 28.5 arc seconds which easily separated them even at a low power of 40x in a 4" telescope. The position angle of the secondary star is 301 degrees.
The primary star, component A, is actually an orange giant star with an M3 spectral type. At 875 light years away, it is the 388th brightest star in the Earth's sky and its iron abundance +0.04 (109.6% of the Sun). It is moving through the Galaxy at a speed of 29.1 km/s relative to the Sun. The spectal type of the B component has been difficult to pin down but appears to classify this star as an A-type main sequence dwarf. The two are separated in the sky by 28.5 arc seconds which easily separated them even at a low power of 40x in a 4" telescope. The position angle of the secondary star is 301 degrees.
My first impression viewing Eta Persei at 130x power in an 8" SCT was that this double lies within a very nice field of nearby stars - an asterism of seven stars forming a kind of chair, with the eighth star sitting on top of it. This pair was already split at lowest magnification (46x). With a moderate-sized telescope and the aid of a finder chart, I was also able to observe the C and F components, which also are part of the chair-asterism, although the D and E components were not detectable that night. Seeing conditions may play a larger part in making these components visible. In any case, the system is a fascinating study of a multiple star system for those with any size telescope and a challenge worth any observers time. See what you can hunt down!
Located at the northwestern tip of Perseus, Eta Persei is a beautiful binocular double star set in small asterism of stars. It can be found in the northeastern sky shortly after the end of twilight. Image with Stellarium.
‘Freakish’ Asteroid Has Six Tails, Sheds Stuff Into Space (November 8, 2013)
by ELIZABETH HOWELL, UniverseToday.com
Pictures of asteroid P/2013 P5 taken by the Hubble Space Telescope. Credit: NASA, ESA, and D. Jewitt (UCLA)
A lawn sprinkler in space. That’s one of the descriptions NASA has for the curious P/2013 P5, which is spewing not one, not two, but six comet-like tails at the same time. “We were literally dumbfounded when we saw it,” stated David Jewitt of the University of California at Los Angeles, who led the research. “Even more amazing, its tail structures change dramatically in just 13 days as it belches out dust. That also caught us by surprise. It’s hard to believe we’re looking at an asteroid.”
UCLA described the asteroid as a ”weird and freakish object” in its own press release.
The mystery started when astronomers spotted a really blotchy thing in space Aug. 27 with the Pan-STARRS survey telescope in Hawaii. The Hubble Space Telescope then swung over to take a look on Sept. 10, revealing all these tails of debris flying off the asteroid.
UCLA described the asteroid as a ”weird and freakish object” in its own press release.
The mystery started when astronomers spotted a really blotchy thing in space Aug. 27 with the Pan-STARRS survey telescope in Hawaii. The Hubble Space Telescope then swung over to take a look on Sept. 10, revealing all these tails of debris flying off the asteroid.
Pan-STARRS PS1 Observatory just before sunrise on Haleakala, Maui. Credit: Harvard-Smithsonian Center for Astrophyiscs
It appears, scientists say, that the asteroid is rotating so quickly that it is ripping its very surface apart. They’ve ruled out a collision because the dust leaves in spurts; calculations by team member Jessica Agarwal of the Max Planck Institute for Solar System Research in Lindau, Germany estimated this happened on April 15, July 18, July 24, Aug. 8, Aug. 26 and Sept. 4.
Once the dust gets loose, the sun’s continuous stream of particles then pushes the debris into these extraordinary tails. It’s also possible that this “radiation pressure” contributed to the asteroid’s high spin rate. It appears the team is looking to find more of these objects to see if this is a way that smaller asteroids commonly fall apart.
“In astronomy, where you find one, you eventually find a whole bunch more,” Jewitt stated. “This is just an amazing object to us, and almost certainly the first of many more to come.”
Once the dust gets loose, the sun’s continuous stream of particles then pushes the debris into these extraordinary tails. It’s also possible that this “radiation pressure” contributed to the asteroid’s high spin rate. It appears the team is looking to find more of these objects to see if this is a way that smaller asteroids commonly fall apart.
“In astronomy, where you find one, you eventually find a whole bunch more,” Jewitt stated. “This is just an amazing object to us, and almost certainly the first of many more to come.”
New Chelyabinsk Results Yield Surprises (November 7, 2013)
by Kelly Beatty, skyandtelescope.com
New analyses suggest that an asteroidal fragment's collision with Earth on February 15, 2013, might not be the once-per-century event that researchers thought. Instead, these potent wallops might occur more frequently and with more destructive power than previously thought.
Anyone living in Chelyabinsk, Russia, and who looked skyward at precisely 9:20:32 a.m. last February 15th, saw the incredible spectacle of a massive meteoric fireball brighter than the early-morning Sun. It broke apart violently 20 to 30 miles (30 to 45 km) up. Then, 88 seconds later, powerful shock waves knocked some residents off their feet, injured more than 1,000 (including flash-induced sunburns), and shattered windows in nearly half of the city's apartment buildings.
Scary close-call aside, scientists count themselves fortunate that the cosmic blast occurred over this urban center. That's because the city's security-obsessed residents captured the event in a myriad of building-mounted video cameras and on dashcams mounted inside their cars. All these looks, combined with defense satellites looking down on Earth from space and a worldwide infrasound network maintained by Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), have allowed researchers to dissect the event with unprecedented precision. Yesterday they made their findings public, in two articles published in Nature and a third in Science.
The object itself was a wayward interloper from the asteroid belt. Careful trajectory reconstruction by Jiří Bobrovička (Astronomical Institute, Czech Academy of Sciences) and others shows that the object came in on a highly elliptical, low-inclination orbit that's a close match to that of theunnamed asteroid 86039. Mostly likely, the two bodies were once part of a single object that sent fragments flying across Earth's path after a violent collision with another asteroid some time in the past.
A color-coded computer model of temperatures inside the residual trail left by the Chelyabinsk bolide, at a time 50 seconds after the object exploded. Note that the outer gray envelope has a roughly cylindrical shape, indicating that the expanding shock wave came from a linear chain of disrupting fragments.
Peter Brown & others
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Comet ISON Racing Past Earth
(November 7, 2013)
Comet ISON is now inside the orbit of Earth and racing toward the sun. Last night, astronomer Alberto Quijano Vodniza of Pasto, Colombia, recorded the comet moving through space at 103,000 mph (46 km/s). Click to set the scene in motion:
"The movie shows the comet's motion over 27 minutes," says Vodniza. Watch it again. "We also caught a satellite."
On Nov. 28th, Comet ISON will fly through the sun's atmosphere little more than a million kilometers above the sun's fiery surface. This raises a question: Is Comet ISON racing toward its doom? Astronomer Matthew Knight of the Lowell Observatory thinks the comet might withstand the heat:
"At its closest point to the Sun, the equilibrium temperature approaches 5000 degrees Fahrenheit, hot enough to cause much of the dust and rock on ISON’s surface to vaporize," says Knight. "While it may seem incredible that anything can survive this inferno, the rate at which ISON will likely lose mass is relatively small compared to how big it likely is. Assuming that the comet's nucleus is bigger than about 200 meters in radius (current estimates suggest it is 500-2000 m in radius), it will likely survive. It helps that the comet is moving very fast, about 400 km/s at perihelion, so it will not remain long at such extreme temperatures."
If Comet ISON does survive its encounter with the sun, it could put on a good show for backyard astronomers in the northern hemisphere in December. The next few weeks will tell the tale.
On Nov. 28th, Comet ISON will fly through the sun's atmosphere little more than a million kilometers above the sun's fiery surface. This raises a question: Is Comet ISON racing toward its doom? Astronomer Matthew Knight of the Lowell Observatory thinks the comet might withstand the heat:
"At its closest point to the Sun, the equilibrium temperature approaches 5000 degrees Fahrenheit, hot enough to cause much of the dust and rock on ISON’s surface to vaporize," says Knight. "While it may seem incredible that anything can survive this inferno, the rate at which ISON will likely lose mass is relatively small compared to how big it likely is. Assuming that the comet's nucleus is bigger than about 200 meters in radius (current estimates suggest it is 500-2000 m in radius), it will likely survive. It helps that the comet is moving very fast, about 400 km/s at perihelion, so it will not remain long at such extreme temperatures."
If Comet ISON does survive its encounter with the sun, it could put on a good show for backyard astronomers in the northern hemisphere in December. The next few weeks will tell the tale.
Young Moon Visits Venus' Neighbourhood (November 5, 2013)
Fresh out of eclipsing the Sun when precisely new, the Moon waxes past Venus in twilight over the next few nights. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. The blue 10° scale is about the size of your fist held at arm's length. For clarity, the Moon is shown three times actual size.)
Northern Taurid Meteor Shower Active Now, Peaks on November 11th
(November 4, 2013)
While the Taurid meteor shower is one of the longest duration showers of the year (active September 10th to December 10th), the coming week brings more intense action to the sky as the Earth enters the second dense part of this cometary debris cloud. The shower actually had a first "peak" of activity earlier in October because of a different concentration of debris material that earth passes through - the Southern Taurids. The Northern part of the Taurid meteor shower peaks on the night of November 11/12. This year presents a good seeing opportunity, as the Moon does not interfere, offering a nice chance to glimpse a few meteors from this very old stream.
The Taurids have long been identified as an old meteor stream, with the first recorded observations made as far back as 1869. Although frequently seen during the remainder of the 19th century, it was not until 1918 that it was realized that a new meteor shower had been found.
The Taurids are somewhat unusual as meteor showers go because of the two separate shower radiants that occur on widely different dates. Scientists now believe that this separation into essentially two different clouds of debris has been caused by the gravitational effect of the planets, especially Jupiter over many decades. Although originating from the same parent comet, overtime they have spread out to form essentially two separate meteor showers. Both the Southern and Northern Taurids have low zenithal hourly rates (ZHR) of between 5-10. Despite the low numbers it's worth looking out for them as they often produce spectacular fireballs! In fact, when bright Taurids come, authorities are usually in for a busy night with a flurry of UFO reports!
Parent Comet and Radiant
The meteors are associated with periodic comet Encke (2P/Encke), which orbits the Sun once every 3.3 years — the shortest period of any known comet. Comet Encke and the Taurids are believed to be remnants of a much larger comet, which has disintegrated over the past 20,000 to 30,000 years. Of course comet Encke is no slouch, putting on a fine show in the early morning sky this month.
The Taurids have long been identified as an old meteor stream, with the first recorded observations made as far back as 1869. Although frequently seen during the remainder of the 19th century, it was not until 1918 that it was realized that a new meteor shower had been found.
The Taurids are somewhat unusual as meteor showers go because of the two separate shower radiants that occur on widely different dates. Scientists now believe that this separation into essentially two different clouds of debris has been caused by the gravitational effect of the planets, especially Jupiter over many decades. Although originating from the same parent comet, overtime they have spread out to form essentially two separate meteor showers. Both the Southern and Northern Taurids have low zenithal hourly rates (ZHR) of between 5-10. Despite the low numbers it's worth looking out for them as they often produce spectacular fireballs! In fact, when bright Taurids come, authorities are usually in for a busy night with a flurry of UFO reports!
Parent Comet and Radiant
The meteors are associated with periodic comet Encke (2P/Encke), which orbits the Sun once every 3.3 years — the shortest period of any known comet. Comet Encke and the Taurids are believed to be remnants of a much larger comet, which has disintegrated over the past 20,000 to 30,000 years. Of course comet Encke is no slouch, putting on a fine show in the early morning sky this month.
Comet 2P/Encke as imaged by Damian Peach on October 12th. Taken with a 20″ CDK telescope and a FLI Proline PL11002 Colr CCD camera; LRGB: L: 6×2 minutes, RGB exposure: 1×2 minutes. (Credit: D. Peach)
The radiant for the Northern Taurids is large and centred at 3h 52m and +22 degrees. This part of the sky is located in the northwest section of the Taurus and only 3 degrees to the southeast of the famous naked eye open cluster, M45 (The Pleiades). The radiant is the location in the sky from which all the meteors of this particular shower seem to originate from. Think it kind of like a point in the distance in front of the windshield of your car from which all the bugs that splatter on front glass seem to come from. By midnight, this region is high overhead, providing excellent sky coverage for seeing the maximum number of shooting stars. Remember, you don't have to look at the radiant to see meteors. They will be found all over the sky, so the best time to see lots of them is when the radiant is high above your head.
Observing Conditions For the Meteor Shower
The waxing moon, which stays out throughout the evening hours for the next few days, sets at about the time that the Taurid meteor shower starts to produce the greatest number of meteors for the night. Once again – no matter where you live worldwide – you’re most likely to see the most North Taurid meteors in the wee hours just after midnight. The North Taurids are generally a very modest shower, offering perhaps 10 meteors per hour on a dark, moonless night. But even one bright meteor can be a treat, especially since a good percentage of the Taurid meteors tend to produce fireballs!
This weekend, the moon will set – or at least be close to setting – as this shower reaches full stride shortly after local midnight. But the moon sets about one hour later with each passing night, providing fewer hours of darkness for enjoying the Taurid shower. The expected peak will fall on the night of November 11-12 (late evening on Monday, November 11, until the wee morning hours on Tuesday, November 12). But by then, a larger and brighter waxing gibbous moon won’t set until a few hours after midnight. If you’re blessed with clear nights this weekend, take advantage of them because you’ll have more moon-free viewing time than early next week!
The waxing moon, which stays out throughout the evening hours for the next few days, sets at about the time that the Taurid meteor shower starts to produce the greatest number of meteors for the night. Once again – no matter where you live worldwide – you’re most likely to see the most North Taurid meteors in the wee hours just after midnight. The North Taurids are generally a very modest shower, offering perhaps 10 meteors per hour on a dark, moonless night. But even one bright meteor can be a treat, especially since a good percentage of the Taurid meteors tend to produce fireballs!
This weekend, the moon will set – or at least be close to setting – as this shower reaches full stride shortly after local midnight. But the moon sets about one hour later with each passing night, providing fewer hours of darkness for enjoying the Taurid shower. The expected peak will fall on the night of November 11-12 (late evening on Monday, November 11, until the wee morning hours on Tuesday, November 12). But by then, a larger and brighter waxing gibbous moon won’t set until a few hours after midnight. If you’re blessed with clear nights this weekend, take advantage of them because you’ll have more moon-free viewing time than early next week!
While the northern Taurid meteor shower doesn't give observers as high an hourly rate of shooting stars as say the Perseids, Geminids, or Leonids, they do make up for it in part through the numerous bright fireballs that are produced.
Thousands Watch Sunrise Solar Eclipse
(November 4, 2013)
On Sunday morning, Nov. 3rd, the New Moon passed in front of the sun, producing a solar eclipse visible from the east Coast of North America to the western side of Africa. In North Carolina, the eclipse was underway when the morning sun rose over the Atlantic Ocean:
While northern Taurid meteors are fewer in the number visible per hour than some of the more well known annual meteor showers, they make up for it with the relatively large number of spectacular fireballs they produce.
"This morning's eclipse was spectacular - even my three sleepyheaded children approved!" says photographer Tavi Greiner, who stationed her on camera on Holden Beach. Farther north, city folk in Manhattan awoke to a spectacular sunrise over the skyline of the skyscraper capital of the world. Here's an image taken by Chris Cook of New York. He states, "This photo shows this mornings partial solar eclipse rising behind the Empire State Building in New York City. I used a Canon 40D and a Canon 400mm f/5.6L lens".
Later, the New Moon covered the entire sun, producing an annular eclipse and then a total solar eclipse visible across the Atlantic and Africa. The narrow path of totality touched several African nations including Gabon, the Congo, Uganda, Kenya, Ethiopia and Somalia. Here's an image of totality taken at 40,000 ft by Ben Cooper on board a private jet over the Atlantic ocean (somewhere southeast of Bermuda|):
New Exoplanet Discovery Boosts Extrasolar Planetary System to 7! (November 1, 2013) by Emily Poore, SkyandTelescope.com
Planet Hunters citizen-science program identifies 14 exoplanet candidates the Kepler mission missed, including a seventh planet in a known system, making it the first seven-planet system discovered.
Halloween is the season of bite-size candy, but who knew there were bite-size planetary systems? The 14 latest discoveries just announced by the Planet Hunters citizen-science program includes a world that gives the Kepler mission its first seven-planet system — and the whole system would fit between the Earth and Sun.
Halloween is the season of bite-size candy, but who knew there were bite-size planetary systems? The 14 latest discoveries just announced by the Planet Hunters citizen-science program includes a world that gives the Kepler mission its first seven-planet system — and the whole system would fit between the Earth and Sun.
So far, Kepler has found systems with up to six planets. The only known system with more planets is our own. But Planet Hunters may have found the first seven-planet system: KOI 351 - a system where Kepler investigators missed a planet. Credit: NASA / Tim Pyle
Planet Hunters is one of the crowdsourcing projects under the
Zooniverse umbrella. Ordinary citizens examine the Kepler spacecraft’s precision light curves of stars that are not currently labeled as Kepler Objects of Interest (KOI) and flag any slight brightness dips that might indicate a planet crossing a star’s face. Many eyes examine each 30-day light-curve segment, and cross checks are built in. False transits are inserted to determine the volunteers’ skill at distinguishing signals from noise, and the volunteers are ranked by how well they replicate each other’s finds. A transit has to repeat with clockwork precision before it is considered “of interest.” Since December 2010, more than 250,000 volunteers have examined more than 19 million Kepler light curves, contributing 180 years of work.
Zooniverse umbrella. Ordinary citizens examine the Kepler spacecraft’s precision light curves of stars that are not currently labeled as Kepler Objects of Interest (KOI) and flag any slight brightness dips that might indicate a planet crossing a star’s face. Many eyes examine each 30-day light-curve segment, and cross checks are built in. False transits are inserted to determine the volunteers’ skill at distinguishing signals from noise, and the volunteers are ranked by how well they replicate each other’s finds. A transit has to repeat with clockwork precision before it is considered “of interest.” Since December 2010, more than 250,000 volunteers have examined more than 19 million Kepler light curves, contributing 180 years of work.
This image shows the distances of the tightly packed seven planet system in comparison to the orbits of the planets in our own solar system. Quite a compact bunch - how do they do that?
Contrary to what many astronomers expected, Planet Hunters has succeeded in spotting not just the transiting objects that computer analysis found, but others that the machine algorithms missed. Planet Hunters has proved most effective at finding new candidates that are Neptune-sized or larger, but it has also identified sub-Neptune exoplanets.
With relatively long orbital periods ranging from 124 to 904 days, eight of the 14 newly announced candidates are in their star’s habitable zone, and two are in multiplanet systems. Their sizes range from roughly Earth’s diameter to super-Jupiters.
With relatively long orbital periods ranging from 124 to 904 days, eight of the 14 newly announced candidates are in their star’s habitable zone, and two are in multiplanet systems. Their sizes range from roughly Earth’s diameter to super-Jupiters.
Light curve with transit for star KIC 6805414 that was missed by the Transit Planet Search (TPS) algorithm.
Source: Schmitt et al.
But it is candidate KOI-351.07 researchers say is the most significant find. If confirmed, as seems very likely, it will make the known six-planet KOI-351 system the first seven-planet system to be pinned down. As it stands, there are only two definite six-planet solar systems (KOI-351 included), and five five-planet systems in the Kepler data.
Light curve with transit for star KIC 6805414 that was missed by the Transit Planet Search (TPS) algorithm.
Source: Schmitt et al.
The five innermost planets are smaller than Neptune, and the outer two are larger gas giants. The new, seventh addition is the farthest out. It seems to be interacting gravitationally with its neighbors, as shown by slight transit-timing variations, raising its probability of planethood even further.
To put the whole thing in context, if we were to place the KOI-351 system around our star, we’d have an entire solar system between Earth and Sun, laid out like ours with the smaller planets closest to the star and giants farthest out.
It’s conceivable that we’re seeing an extremely unlikely alignment of two different systems orbiting two different stars along almost exactly the same line of sight. However, no such coincidence has yet been found for any of the other 500+ multiplanet systems observed by Kepler. With those odds, we almost certainly have a new recruit joining the elite club of 7-and-overs, which up until this discovery contained only our home solar system.
For the fascinating details of how Planet Hunters works and how its latest discoveries were teased out, see the research team’s paper.
To put the whole thing in context, if we were to place the KOI-351 system around our star, we’d have an entire solar system between Earth and Sun, laid out like ours with the smaller planets closest to the star and giants farthest out.
It’s conceivable that we’re seeing an extremely unlikely alignment of two different systems orbiting two different stars along almost exactly the same line of sight. However, no such coincidence has yet been found for any of the other 500+ multiplanet systems observed by Kepler. With those odds, we almost certainly have a new recruit joining the elite club of 7-and-overs, which up until this discovery contained only our home solar system.
For the fascinating details of how Planet Hunters works and how its latest discoveries were teased out, see the research team’s paper.
Four Bright(ish) Comets Haunt Our Morning Skies! (October 31, 2013)
by Bob King, UniverseToday.com
No fewer than four bright-ish comets greet skywatchers an hour before the start of dawn. From upper left counterclockwise: C/2013 R1 Lovejoy, 2P/Encke, C/2012 X1 and ISON. Credits: Gerald Rhemann, Damian Peach, Gianluca Masi and Gerald Rhemann
Get your astronomical trick-or-treat bags ready. An excursion under the Halloween morning sky will allow you fill it in a hurry — with comets! We’ve known for months that ISON and 2P/Encke would flick their tails in the October dawn, but no one could predict they’d be joined by Terry Lovejoy’s recent comet discovery, C/2013 R1 (Lovejoy), and the obscure C/2012 X1 (LINEAR). The last surprised all of us when it suddenly brightened by more than 200 times in a matter of days. Almost overnight, a comet found on precious few observing lists became bright enough to see in binoculars. Now comet watchers the world over are losing sleep to get a glimpse of it.
Detailed map showing Comet Lovejoy’s progress across Cancer in the coming days. Click for a larger version you can print and use under the stars. The stars Beta Cancri and Procyon will be your guides. All dates are at 6 a.m. CDT; north is up and west to the right and stars are shown to mag. 9. All closeup charts created with Chris Marriott’s SkyMap software
Brightest of the bunch at magnitude 8 and your best bet to see in a standard pair of 50mm binoculars is Comet Lovejoy. Using the maps, look for a round, fuzzy spot with a brighter center not far from the bright star Procyon in Canis Minor. In the coming days, Lovejoy will brighten by an additional 2 to 3 magnitudes as it trucks across Cancer headed toward the Big Dipper. This is one to watch. Lovejoy will likely reach naked eye brightness by mid-November. Small telescope users can see the comet with ease but its developing gas tail is still to faint to spot visually.
Comet Encke drops below Leo and into Virgo over the next two weeks. Your guide star Beta Leo is at upper right. Stars to mag.8. Click to enlarge.
Comet Encke treks around the sun every 3.3 years. Sometimes it’s well placed for viewing and sometimes not. Because of its short period, dedicated comet watchers meet up with it a half dozen or more times during their lives. This apparition is a favorable one with the comet well-positioned in the east at dawn near peak brightness. Current estimates place it magnitude 7.5-8 with only the wispiest of tails. Like Lovejoy, 50mm binoculars under a dark sky should nab it.
A week before Encke reaches its peak magnitude of 6 or 7 at perihelion on Nov. 21, it chases the into the glare of morning twilight. If you want to see this comet, you’ve got about 2 weeks of viewing time left. Make sure to set up in a place with an open view to the east-southeast or you’ll find it hidden by the treeline.
A week before Encke reaches its peak magnitude of 6 or 7 at perihelion on Nov. 21, it chases the into the glare of morning twilight. If you want to see this comet, you’ve got about 2 weeks of viewing time left. Make sure to set up in a place with an open view to the east-southeast or you’ll find it hidden by the treeline.
Animation from images taken Oct. 25 and 28 of comet C/2012 X1 (LINEAR) showing its rapidly expanding coma in the wake of an eruptive event in its icy crust. Click image to animate. Credit: Gianluca Masi
Comet C/2012 X1 would have deprived us of a unique sight had it followed the rules. Instead, an eruption of fresh, dust-laden ices from its surface blasted into space to form a gigantic glowing sphere of material that vaulted the comet’s magnitude from a wimpy 13.5 to a vol-luminous 7.5. That’s a difference of 6 magnitudes or a brightness factor of 250 times!
Outbursts of this consequence are rare; the best example of a similar blow-out happened in 2007 when Comet 17P/Holmes cut loose and brightened by half a million times from magnitude 17 to 2.8 in just under two days.
Outbursts of this consequence are rare; the best example of a similar blow-out happened in 2007 when Comet 17P/Holmes cut loose and brightened by half a million times from magnitude 17 to 2.8 in just under two days.
C/2012 X1 (LINEAR) hovers low in the northeast in Coma Berenices near Beta. Because it’s much further from Earth than the other three comets, it moves more slowly across the sky. It has a close conjunction with the brilliant star Arcturus in mid-November. In this map, north is at top left and west to top right. Stars to mag. 8. Click to enlarge.
As with any explosion, the cloud of debris around C/2012 X1 continues to expand. Presently measuring a healthy ~8 arc minutes in diameter (1/4 the size of the full moon), the comet will almost certainly continue to grow and fade with time. Catch it now with binoculars and small telescopes before its veil-like coma thins to invisibility. Like Encke, X1 LINEAR requires an open eastern horizon and best viewed at the start of dawn. Make it the last comet on your observing list after Lovejoy, Encke and ISON.
Mars and several other moderately bright stars in Leo will guide you to Comet ISON in the next week or two. Stars to mag. 10. Click to enlarge.
Ah, ISON. Halloween morning wouldn’t be complete without a visit to this year’s the most anticipated comet.. If it can hold itself together after a searing graze of the sun on November 28, the comet will undoubtedly become a most pleasing sight during the first three weeks of December. Right now it’s a little behind schedule on brightness, but don’t let that worry you – its best days are still ahead.
One of the finest pictures to date of Comet ISON by ace astrophotographer Damian Peach taken on Oct. 27.
Of our four morning treats, Comet ISON is currently the faintest at around magnitude 9.5. Observers with binoculars in the 70-100mm range will see it under dark skies but most of us will need a 6-inch or larger scope at least until mid-November. That’s when ISON’s expected to brighten to magnitude 6, the naked eye limit. Just before it slips into the solar glare, ISON could reach 3rd magnitude around Nov. 21, normally an easy catch with the naked eye, but low altitude will hamper the view.
So open your bag wide tomorrow before dawn and keep it open the next few mornings. Trick or treat!
So open your bag wide tomorrow before dawn and keep it open the next few mornings. Trick or treat!
Rarely are four comets this bright in the same quadrant of sky. This map shows the sky facing east about two hours before sunrise on Oct. 31. Take note of the three stars are labeled “Beta”. These are (from top) Beta Cancri, Beta Leonis and Beta Coma Berenices. We’ll use these three stars and the planet Mars to hone in on the comets’ locations in the maps below. Stellarium
Rare Hybrid Solar Eclipse Makes Its Appearance Sunday (October 29, 2013)
A partially eclipsed setting Sun as seen from Dallas, Texas on May 20th, 2012. This weekend’s eclipse will offer U.S. East Coast residents a similar sunrise view. (Credit: Jason Major/Lights in the Dark).
It’s almost upon us. The final eclipse of 2013 occurs this coming weekend on Sunday, November 3rd. This will be the fifth eclipse overall, and the second solar eclipse of 2013. This will also be the only eclipse this year that features a glimpse of totality.
This eclipse is of the rare hybrid variety— that is, it will be an annular eclipse along the very first 15 seconds of its track before transitioning to a total as the Moon’s shadow sweeps just close enough to the Earth to cover the disk of the Sun along the remainder of its track.
How rare are hybrid solar eclipse? Of the 11,898 solar eclipses listed over a 5,000 year span from 1999 BC to 3000 AD in Fred Espenak’s Five Millennium Catalog of Solar Eclipses, only 569, or 4.8% are hybrids.
This eclipse is of the rare hybrid variety— that is, it will be an annular eclipse along the very first 15 seconds of its track before transitioning to a total as the Moon’s shadow sweeps just close enough to the Earth to cover the disk of the Sun along the remainder of its track.
How rare are hybrid solar eclipse? Of the 11,898 solar eclipses listed over a 5,000 year span from 1999 BC to 3000 AD in Fred Espenak’s Five Millennium Catalog of Solar Eclipses, only 569, or 4.8% are hybrids.
An animation of the path of the November 3rd hybrid solar eclipse. (Credit: NASA/Goddard Space Flight Center).
Who can see this eclipse?
People from northern South America, across the U.S. Eastern Seaboard and up through the Canadian Maritimes will see a brief partial solar eclipse finishing up around 30 minutes after local sunrise. The brief annular “ring of fire” portion of the eclipse begins at sunrise just ~1,000 kilometres east of Jacksonville, Florida, as it races eastward across the Atlantic. See the timeline, below.
People from northern South America, across the U.S. Eastern Seaboard and up through the Canadian Maritimes will see a brief partial solar eclipse finishing up around 30 minutes after local sunrise. The brief annular “ring of fire” portion of the eclipse begins at sunrise just ~1,000 kilometres east of Jacksonville, Florida, as it races eastward across the Atlantic. See the timeline, below.
Eclipse prospects for the US East Coast. (Courtesy of Michael Zeiler @EclipseMaps)
Nearly all of Africa and the southern Mediterranean region including Spain will see partial phases of the eclipse, while greatest totality occurs just off of the coast of Liberia and heads for first landfall on the African continent over Wonga Wongue Reserve in Gabon. At this point, the duration of totality will already have shrunk back down to 1 minute and 7 seconds. The shadow of the Moon will then cross central Africa, headed for a short but brilliant sunset total eclipse over Uganda, Ethiopia, Kenya and Somalia.
This particular eclipse part of saros series 143 and is member 23 of the 72 eclipses in the cycle. The first eclipse in this saros occurred on March 7th, 1617, and the last one will occur on April 23rd, 2897.
Saros 143 also has a checkered place in eclipse history. The last eclipse in this series crossed south eastern Asia on October 24th, 1995.
We’ve compiled a brief worldwide timeline for the November 3rd hybrid eclipse. Keep in mind, the shift back off of Daylight Saving Time occurs on the same morning as the eclipse for North America, putting the U.S. East Coast once again back to -5 hours off of Universal Time (UT):
10:04 UT: The partial phases of the eclipse begin.
11:05:17 UT: annular phases of the eclipse begin.
11:05:36 UT: The eclipse transitions from an annular to a total along its track.
12:46: The point of greatest eclipse, occurring off of the SW coast of Liberia along the coast of Africa. The path will be 57 kilometres wide at this point with a maximum duration for totality at 1 minute & 40 seconds.
14:27 UT: The total phases of the eclipse end.
15:28 UT: Partial phases end.
Remember that solar safety is paramount while observing an eclipse during all partial phases. This is especially critical, as millions of viewers along the U.S. East Coast are poised to catch the eclipse at sunrise over the Atlantic on Sunday. Use only glasses designed specifically for eclipse viewing or welder’s glass #14. One project headed by Astronomers Without Borders is also working to provide eclipse glasses to schools in Africa.
Saros 143 also has a checkered place in eclipse history. The last eclipse in this series crossed south eastern Asia on October 24th, 1995.
We’ve compiled a brief worldwide timeline for the November 3rd hybrid eclipse. Keep in mind, the shift back off of Daylight Saving Time occurs on the same morning as the eclipse for North America, putting the U.S. East Coast once again back to -5 hours off of Universal Time (UT):
10:04 UT: The partial phases of the eclipse begin.
11:05:17 UT: annular phases of the eclipse begin.
11:05:36 UT: The eclipse transitions from an annular to a total along its track.
12:46: The point of greatest eclipse, occurring off of the SW coast of Liberia along the coast of Africa. The path will be 57 kilometres wide at this point with a maximum duration for totality at 1 minute & 40 seconds.
14:27 UT: The total phases of the eclipse end.
15:28 UT: Partial phases end.
Remember that solar safety is paramount while observing an eclipse during all partial phases. This is especially critical, as millions of viewers along the U.S. East Coast are poised to catch the eclipse at sunrise over the Atlantic on Sunday. Use only glasses designed specifically for eclipse viewing or welder’s glass #14. One project headed by Astronomers Without Borders is also working to provide eclipse glasses to schools in Africa.
10th Anniversary of Halloween Auroral Superstorm (October 30, 2013)
Yesterday marked the 10th anniversary of a spectacular geomagnetic storm that later became known as the great Halloween super storm of 2003. On October 28th, 2003, an X1.7 solar flare propelled a large CME towards Earth that directly led to an extreme geomagnetic storm a day later. The aurorae created by this event were spectacular and seen across much of the world. Below is a video detailing the events that took place.
Main Belt Asteroid Massalia Reaches Opposition This Week (October 28, 2013)
Asteroid 20 Massalia reaches opposition later this week and will be well placed for observation, lying in the constellation Aries, well above the horizon for much of the night. 20 Massalia is a large and fairly bright main-belt asteroid orbiting at an average distance of 2.4 AU from the sun. It is also the largest member of the Massalia family of asteroids measuring
160×145×132 km in size. Its name is the Greek name for Marseille, the city from which one of the two independent co-discovers, Jean Chacornac, first sighted it. The asteroid should be visible in binoculars as it has brightened to magnitude 8.7 this week as it has drawn closer to Earth.
20 Massalia is an interesting main belt asteroid for reasons beyond its above average relative brightness. It is an S-type asteroid. It orbits at very low inclination in the intermediate main belt, and is by far the largest asteroid in the Massalia family. The remaining family members are fragments ejected by a cratering event on Massalia. Massalia has an above-average density for S-type asteroids, similar to the density of silicate rocks. As such, it appears to be a solid un-fractured body, a rarity among asteroids of its size. Apart from the few largest bodies over 400 km in diameter, such as 1 Ceres and 4 Vesta, most asteroids appear to have been significantly fractured, or are even rubble piles.
Also of note with this asteroid - lightcurve analysis indicates that Massalia's poles points at a severe angle to the plane of its orbit - models suggest a 45 degree axial tilt. The shape reconstruction from lightcurves has been described as quite spherical with large planar, nonconvex parts of the surface.
160×145×132 km in size. Its name is the Greek name for Marseille, the city from which one of the two independent co-discovers, Jean Chacornac, first sighted it. The asteroid should be visible in binoculars as it has brightened to magnitude 8.7 this week as it has drawn closer to Earth.
20 Massalia is an interesting main belt asteroid for reasons beyond its above average relative brightness. It is an S-type asteroid. It orbits at very low inclination in the intermediate main belt, and is by far the largest asteroid in the Massalia family. The remaining family members are fragments ejected by a cratering event on Massalia. Massalia has an above-average density for S-type asteroids, similar to the density of silicate rocks. As such, it appears to be a solid un-fractured body, a rarity among asteroids of its size. Apart from the few largest bodies over 400 km in diameter, such as 1 Ceres and 4 Vesta, most asteroids appear to have been significantly fractured, or are even rubble piles.
Also of note with this asteroid - lightcurve analysis indicates that Massalia's poles points at a severe angle to the plane of its orbit - models suggest a 45 degree axial tilt. The shape reconstruction from lightcurves has been described as quite spherical with large planar, nonconvex parts of the surface.
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Regardless of your location on the Earth, Massalia will reach its highest point in the sky at around midnight local time.
This optimal positioning occurs when it makes its closest approach to the point in the sky directly opposite to the Sun – an event termed opposition, the exact moment of which will be 21:09 UTC. Since the Sun reaches its greatest distance below the horizon at midnight, the point opposite to it is highest in the sky at the same time.
At around the same time that Massalia passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest in the night sky. This happens because when Massalia lies opposite to the Sun in the night sky, the Solar System is lined up so that Massalia, the Earth and the Sun lie in a straight line with the Earth in the middle, on the same side of the Sun as Massalia.
On this occasion, Massalia will pass within 1.232 AU of us, reaching a peak brightness of magnitude 8.7. Nonetheless, even at its brightest, Massalia is a faint object beyond the reach of the naked eye; a pair of binoculars or a telescope and a good star chart are needed.
At the moment of opposition, Massalia will lie at a declination of +14°06' , and so will be seen to best advantage in the northern hemisphere. It will be possible to see it at latitudes between 84°N and 55°S.
This optimal positioning occurs when it makes its closest approach to the point in the sky directly opposite to the Sun – an event termed opposition, the exact moment of which will be 21:09 UTC. Since the Sun reaches its greatest distance below the horizon at midnight, the point opposite to it is highest in the sky at the same time.
At around the same time that Massalia passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest in the night sky. This happens because when Massalia lies opposite to the Sun in the night sky, the Solar System is lined up so that Massalia, the Earth and the Sun lie in a straight line with the Earth in the middle, on the same side of the Sun as Massalia.
On this occasion, Massalia will pass within 1.232 AU of us, reaching a peak brightness of magnitude 8.7. Nonetheless, even at its brightest, Massalia is a faint object beyond the reach of the naked eye; a pair of binoculars or a telescope and a good star chart are needed.
At the moment of opposition, Massalia will lie at a declination of +14°06' , and so will be seen to best advantage in the northern hemisphere. It will be possible to see it at latitudes between 84°N and 55°S.
This Stellarium image shows 20 Massalia at about 10 PM fairly high in the east-southeast below Hamal, the brightest star in the constellation of Aries the ram.
Click on image for PDF printable finder chart.
Comet C/2013 R1 Lovejoy Brightens and Grows a Tail! (October 27, 2013)
Just to make sure we hadn't forgotten about it with all these other comets in the eastern morning sky, Comet C/2013 R1 Lovejoy has brightened to magnitude 9 and grown a thin short tail! John Chumack, of Ohio captured the image below on the night of Oct. 26th, showing a large bright green coma surrounding the nucleus and pencil-thin tail sprouting out behind it. John reports, "Comet Lovejoy 2013 R1 is getting spectacular ....I found it has developed a faint long tail this morning....it is at least 12 arc minutes in length and the Comets Coma is now around 6 arc minutes in diameter .. ...This the fourth comet discovered by Terry Lovejoy! So glad to see his new bright Comet starting to put on a nice show!!!
Comet Lovejoy, having brightened now to magnitude +9 is quickly developing a bright and large greenish coma around its nucleus and sprouted a 12 arc minute long tail. This is a 60 minute exposure (30 x 2 minute subs) was taken tracking on the comets nucleus on 10-26-2013 from 07:23 U.T until 08:30 U.T. using a QHY8 cooled Color CCD Camera & 16" diameter F4.5 Newtonian telescope. Credit: John Chumack.
The comet is current located south of the planet Jupiter, in the constellation Canis Minor. Below is a map showing its general location. Click on the image for a more detailed printable PDF format finder chart.
Comet C/2012 X1 (Linear) Shows Jets Erupting During Massive Outburst
(October 26, 2013)
The sun isn't the only thing exploding. Almost 450 million km from Earth, Comet C/2012 X1 (LINEAR) is having its own outburst. On Oct. 20th, amateur astronomers realized that the comet's brightness had increased 100-fold and its morphology resembled that of exploding Comet 17P/ Holmes in 2007. Follow-up images in recent nights seem to show jet-like structures in Comet LINEAR X1's expanding atmosphere. Amateur astronomer Nick James of Chelmsford, UK, obtained these data on Oct. 26th:
Click to enlarge
Astronomers Shed New Light on the Rarest and Brightest Exploding Stars
(October 25, 2013)
A newly published study sheds new light on star death, finding that the brightest supernovae are the result of a type of explosion within the star’s core which creates a smaller but extremely dense and rapidly spinning magnetic star.
Artist’s impression of a highly magnetic neutron star called a magnetar.
Astronomers at Queen’s University have shed new light on the rarest and brightest exploding stars ever discovered in the universe.
The research is published on Thursday (17 October) in Nature Magazine – one of the world’s most prestigious science publications. It proposes that the most luminous supernovae – exploding stars – are powered by small and incredibly dense neutron stars, with gigantic magnetic fields that spin hundreds of times a second.
Scientists at Queen’s Astrophysics Research Center observed two super-luminous supernovae – two of the Universe’s brightest exploding stars – for more than a year. Contrary to existing theories, which suggested that the brightest supernovae are caused by super-massive stars exploding, their findings suggest that their origins may be better explained by a type of explosion within the star’s core which creates a smaller but extremely dense and rapidly spinning magnetic star.
Matt Nicholl, a research student at the Astrophysics Research Center at Queen’s School of Mathematics and Physics, is lead author of the study. He said: “Supernovae are several billions of times brighter than the Sun, and in fact are so bright that amateur astronomers regularly search for new ones in nearby galaxies. It has been known for decades that the heat and light from these supernovae come from powerful blast-waves and radioactive material.
The research is published on Thursday (17 October) in Nature Magazine – one of the world’s most prestigious science publications. It proposes that the most luminous supernovae – exploding stars – are powered by small and incredibly dense neutron stars, with gigantic magnetic fields that spin hundreds of times a second.
Scientists at Queen’s Astrophysics Research Center observed two super-luminous supernovae – two of the Universe’s brightest exploding stars – for more than a year. Contrary to existing theories, which suggested that the brightest supernovae are caused by super-massive stars exploding, their findings suggest that their origins may be better explained by a type of explosion within the star’s core which creates a smaller but extremely dense and rapidly spinning magnetic star.
Matt Nicholl, a research student at the Astrophysics Research Center at Queen’s School of Mathematics and Physics, is lead author of the study. He said: “Supernovae are several billions of times brighter than the Sun, and in fact are so bright that amateur astronomers regularly search for new ones in nearby galaxies. It has been known for decades that the heat and light from these supernovae come from powerful blast-waves and radioactive material.
Images of a superluminous supernova SN 2008am obtained with the Keck I telescope's Low Resolution Imaging Spectrometer (LRIS) back in 2008.The galaxy in which this star exploded is 3.7 billion light-years away from Earth. At its peak luminosity, it was over 100 billion times brighter than the Sun. It emitted enough energy in one second to satisfy the power needs of the United States for one million times longer than the universe has existed. Credit: D. Perley & J. Bloom / W.M. Keck Observatory
“But recently some very unusual supernovae have been found, which are too bright to be explained in this way. They are hundreds of times brighter than those found over the last fifty years and the origin of their extreme properties is quite mysterious.
“Some theoretical physicists predicted these types of explosions came from the biggest stars in the universe destroying themselves in a manner quite like a giant thermonuclear bomb. But our data doesn’t match up with this theory.
“In a supernova explosion, the star’s outer layers are violently ejected, while its core collapses to form an extremely dense neutron star – weighing as much as the Sun but only tens of kilometers across. We think that, in a small number of cases, the neutron star has a very strong magnetic field, and spins incredibly quickly – about 300 times a second. As it slows down, it could transmit the spin energy into the supernova, via magnetism, making it much brighter than normal. The data we have seems to match that prediction almost exactly.”
“Some theoretical physicists predicted these types of explosions came from the biggest stars in the universe destroying themselves in a manner quite like a giant thermonuclear bomb. But our data doesn’t match up with this theory.
“In a supernova explosion, the star’s outer layers are violently ejected, while its core collapses to form an extremely dense neutron star – weighing as much as the Sun but only tens of kilometers across. We think that, in a small number of cases, the neutron star has a very strong magnetic field, and spins incredibly quickly – about 300 times a second. As it slows down, it could transmit the spin energy into the supernova, via magnetism, making it much brighter than normal. The data we have seems to match that prediction almost exactly.”
Queen’s astronomers led an international team of scientists on the study, using some of the world’s most powerful telescopes. Much of the data was collected using Pan-STARRS – the Panoramic Survey Telescope and Rapid Response System. Based on Mount Haleakala in Hawaii, Pan-STARRS boasts the world’s largest digital camera, and can cover an area 40 times the size of the full moon in one shot.
The study is one of the projects funded by a prestigious €2.3million grant from the European Research Council. The grant was awarded to Professor Stephen Smartt, Director of Queen’s Astrophysics Research Center, in 2012 to lead an international study to hunt for the Universe’s earliest supernovae.
Professor Smartt said: “These are really special supernovae. Because they are so bright, we can use them as torches in the very distant Universe. Light travels through space at a fixed speed, as we look further away, we see snapshots of the increasingly distant past. By understanding the processes that result in these dazzling explosions, we can probe the Universe as it was shortly after its birth. Our goal is to find these supernovae in the early Universe, detecting some of the first stars ever to form and watch them produce the first chemical elements created in the Universe.”
The study is one of the projects funded by a prestigious €2.3million grant from the European Research Council. The grant was awarded to Professor Stephen Smartt, Director of Queen’s Astrophysics Research Center, in 2012 to lead an international study to hunt for the Universe’s earliest supernovae.
Professor Smartt said: “These are really special supernovae. Because they are so bright, we can use them as torches in the very distant Universe. Light travels through space at a fixed speed, as we look further away, we see snapshots of the increasingly distant past. By understanding the processes that result in these dazzling explosions, we can probe the Universe as it was shortly after its birth. Our goal is to find these supernovae in the early Universe, detecting some of the first stars ever to form and watch them produce the first chemical elements created in the Universe.”
A Timely Cover-Up By Ceres
(October 24, 2013) by Kelly Beatty, SkyandTelescope.com
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Ceres is the largest asteroid and the smallest dwarf planet. On October 25th, it will occult a faint star in Virgo. Results from amateur observers could aid the forthcoming arrival of NASA's Dawn spacecraft.
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The surface of Ceres, as revealed by the Hubble Space Telescope's Advanced Camera for Surveys, includes several brighter and darker regions that could be caused by impacts. Ceres itself is slightly wider at its equator than at its poles.
NASA, ESA, J. Parker (Southwest Research Institute), and others
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Fresh off last week's stellar occultation involving Patroclus, a binary Trojan asteroid out near Jupiter, David Dunham, who heads the International Occultation Timing Association (IOTA) has again put out a call for assistance in recording an asteroid that is about to cover up a star.
This time the event involves 1 Ceres, which is both the largest known asteroid and the smallest known dwarf planet. But it's also the destination of NASA's Dawn spacecraft, now en route, and this occultation is the last before Dawn's arrival in February 2015.
Although Ceres has been resolved repeatedly by the Hubble Space Telescope and by ground-based observatories, careful occultation records have the potential to determine both the body's true diameter (estimated at about 590 miles or 950 km) and how much its shape deviates from a perfect sphere — keys to understanding its interior structure.
The occultation takes place Friday, October 25th, from 9:40 to 9:46 Universal Time. As the map shows, the wide occultation track favors the Eastern Hemisphere, but it will be daytime in that part of the world during the event. So IOTA's efforts are focused on the East Coast of the U.S., where Ceres will be low in the eastern sky before dawn.
This time the event involves 1 Ceres, which is both the largest known asteroid and the smallest known dwarf planet. But it's also the destination of NASA's Dawn spacecraft, now en route, and this occultation is the last before Dawn's arrival in February 2015.
Although Ceres has been resolved repeatedly by the Hubble Space Telescope and by ground-based observatories, careful occultation records have the potential to determine both the body's true diameter (estimated at about 590 miles or 950 km) and how much its shape deviates from a perfect sphere — keys to understanding its interior structure.
The occultation takes place Friday, October 25th, from 9:40 to 9:46 Universal Time. As the map shows, the wide occultation track favors the Eastern Hemisphere, but it will be daytime in that part of the world during the event. So IOTA's efforts are focused on the East Coast of the U.S., where Ceres will be low in the eastern sky before dawn.
The shaded path represents Ceres's "shadow" during the asteroid's occultation of a 10th-magnitude star from 9:40 to 9:46 Universal Time on October 25, 2013. At that time the Eastern Hemisphere will be in daylight, but the event should be visible before dawn to observers along the East Coast of North America. Click on the image for a larger version.
Those inside a zone from southern Maine to South Carolina, and no farther inland than a line from southern Michigan to northern Georgia, have a chance to see it.
"The forecast shows that it should be clear along the Atlantic coast (the only hiccup is a band of cloudiness predicted near the NC-VA border)," Dunham reports, "so I hope that many observers can try this, the second valuable asteroidal occultation in the U.S. this week!"
This will not be an easy observation, however — and not simply because you'll have to get up before dawn. Right now Ceres is magnitude 8.8, three times brighter than the 10.0-magnitude star it will cover up. (Typically the occulting asteroid is much fainter than the target star.) Light from a last-quarter Moon will add to the challenge.
Moreover, while the occultation might last from a few to up to 22.5 seconds, depending on your location, the drop in light will be only about 0.3 magnitude. That slight dip would be quite challenging to detect visually. Instead, ideally you should use an 8-inch or larger telescope, preferably equipped with a video camera.
Alternately, suggests by veteran Australian observer John Broughton, you could use a single long exposure with a cooled astro-camera. "The trick is to point the telescope to certain coordinates (not at the target) and to turn off sidereal tracking at a particular time," Broughton explains. "The occultation target star will then drift into the field of view on schedule, shortly before the exposure is started, and the resulting star-trail image can be analyzed photometrically."
For more information, check the Ceres page of IOTA's website.
"The forecast shows that it should be clear along the Atlantic coast (the only hiccup is a band of cloudiness predicted near the NC-VA border)," Dunham reports, "so I hope that many observers can try this, the second valuable asteroidal occultation in the U.S. this week!"
This will not be an easy observation, however — and not simply because you'll have to get up before dawn. Right now Ceres is magnitude 8.8, three times brighter than the 10.0-magnitude star it will cover up. (Typically the occulting asteroid is much fainter than the target star.) Light from a last-quarter Moon will add to the challenge.
Moreover, while the occultation might last from a few to up to 22.5 seconds, depending on your location, the drop in light will be only about 0.3 magnitude. That slight dip would be quite challenging to detect visually. Instead, ideally you should use an 8-inch or larger telescope, preferably equipped with a video camera.
Alternately, suggests by veteran Australian observer John Broughton, you could use a single long exposure with a cooled astro-camera. "The trick is to point the telescope to certain coordinates (not at the target) and to turn off sidereal tracking at a particular time," Broughton explains. "The occultation target star will then drift into the field of view on schedule, shortly before the exposure is started, and the resulting star-trail image can be analyzed photometrically."
For more information, check the Ceres page of IOTA's website.
Ceres is currently located in western Virgo and is low in the eastern sky in the hours before sunrise. Remember that the occultation starts at 5:46 AM and only lasts for 1-14 seconds for most North American observers, depending on your location. The farther east you are, the long the duration of the occultation.
Why Is Comet ISON Green?
(October 24, 2013) by Nancy Atkinson, UniverseToday.com
Comet ISON on October 4, 2013 as seen over Arizona, viewed with a 12.5″ telescope, over an hour exposure time. Credit and copyright: Chris Schur.
Undoubtedly, you’ve been seeing the recent images of Comet ISON now that it is approaching its close encounter with the Sun on November 28. ISON is currently visible to space telescopes like the Hubble and amateur astronomers with larger telescopes. But you might be wondering why many images show the comet with a green-ish “teal” or blue-green color.
Amateur Astronomer Chris Schur has put together this great graphic which provides information on the spectra of what elements are present in the comet’s coma.
For the conspiracy theorists out there, the green color is actually a good omen, and lots of comets display this color. The green color is a sign the comet is getting more active as gets closer to the Sun – meaning it is now putting on a good show for astronomers, and if it can continue to hold itself together, it might become one of the brightest comets in the past several years.
“ISON’s green color comes from the gases surrounding its icy nucleus,” says SpaceWeather.com’s Tony Phillips. “Jets spewing from the comet’s core probably contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C2). Both substances glow green when illuminated by sunlight in the near-vacuum of space.”
Amateur Astronomer Chris Schur has put together this great graphic which provides information on the spectra of what elements are present in the comet’s coma.
For the conspiracy theorists out there, the green color is actually a good omen, and lots of comets display this color. The green color is a sign the comet is getting more active as gets closer to the Sun – meaning it is now putting on a good show for astronomers, and if it can continue to hold itself together, it might become one of the brightest comets in the past several years.
“ISON’s green color comes from the gases surrounding its icy nucleus,” says SpaceWeather.com’s Tony Phillips. “Jets spewing from the comet’s core probably contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C2). Both substances glow green when illuminated by sunlight in the near-vacuum of space.”
Recent images of Comet ISON along with spectral data. Credit and copyright: Chris Schur.
Both are normally colorless gases that fluoresce a green color when excited by energetic ultraviolet light in sunlight.
And if those poisonous gasses sound dangerous, don’t worry. They are spread out in space much too thinly to touch us here on Earth. So don’t fall prey to fear mongers who are out to bilk the masses – like people did in 1910 when Comet Halley made a return to the skies and swindlers pitched their ‘gas masks’ and special ‘comet pills’ for protection. And of course, nothing happened.
But back to the color. Chris Schur provided this info along with his graphic:
Your readers may appreciate knowing why comets can appear this color. The background image is the shot I took with my 12.5″ and an ST10xme CCD camera for 20 minutes in mid-October. A pale coloration of the front of the coma is seen. To the lower left is a shot with the same instrument but with a 100 lpmm (line pair per millimeter) diffraction grating in front of the CCD chip to break out the spectra of the objects in the entire field.
Here ISON is faintly seen to the left of center, and the first order spectra a band to its right. But the real answer comes when we use the software called Rspec to analyze this band of light. The result is on the lower right. Normally reflected sunlight is rather flat and bland, and mostly that is what ISON is right now, reflected from dust. But labeled are two humps in the blue and green parts of the spectrum labeled “C2″ for a carbon molecule. This blue/green emission pair is what gives ISON the color.
Chris notes that as the comet nears the Sun, astronomers and astrophotographers will be able to resolve more spectral details in the comet. “It will be exciting to watch the changes as more molecules pop out,” Chris said via email, “and possibly when it is closest to the Sun, we just may see some metal lines like iron or magnesium from MELTED vaporized rock. How exciting!”
And for those who insist there is something nefarious about Comet ISON, take a look at this FAQ from our friend Stuart Atkinson, who hosts the great site Waiting for ISON. He addresses the many conspiracy theories that are out there regarding this comet.
And if those poisonous gasses sound dangerous, don’t worry. They are spread out in space much too thinly to touch us here on Earth. So don’t fall prey to fear mongers who are out to bilk the masses – like people did in 1910 when Comet Halley made a return to the skies and swindlers pitched their ‘gas masks’ and special ‘comet pills’ for protection. And of course, nothing happened.
But back to the color. Chris Schur provided this info along with his graphic:
Your readers may appreciate knowing why comets can appear this color. The background image is the shot I took with my 12.5″ and an ST10xme CCD camera for 20 minutes in mid-October. A pale coloration of the front of the coma is seen. To the lower left is a shot with the same instrument but with a 100 lpmm (line pair per millimeter) diffraction grating in front of the CCD chip to break out the spectra of the objects in the entire field.
Here ISON is faintly seen to the left of center, and the first order spectra a band to its right. But the real answer comes when we use the software called Rspec to analyze this band of light. The result is on the lower right. Normally reflected sunlight is rather flat and bland, and mostly that is what ISON is right now, reflected from dust. But labeled are two humps in the blue and green parts of the spectrum labeled “C2″ for a carbon molecule. This blue/green emission pair is what gives ISON the color.
Chris notes that as the comet nears the Sun, astronomers and astrophotographers will be able to resolve more spectral details in the comet. “It will be exciting to watch the changes as more molecules pop out,” Chris said via email, “and possibly when it is closest to the Sun, we just may see some metal lines like iron or magnesium from MELTED vaporized rock. How exciting!”
And for those who insist there is something nefarious about Comet ISON, take a look at this FAQ from our friend Stuart Atkinson, who hosts the great site Waiting for ISON. He addresses the many conspiracy theories that are out there regarding this comet.
There Are Now Officially Over 1,000 Confirmed Exoplanets! (October 23, 2013)
by Jason Major, UniverseToday.com
More than 1,000 exoplanets have now been confirmed and cataloged (PHL @ UPR Arecibo)
It was just last week that we reported on the oh-so-close approach to 1,000 confirmed exoplanets discovered thus far, and now it’s official: the Extrasolar Planets Encyclopedia now includes more than 1,000! (1,010, to be exact.) 21 years after the first planets beyond our own Solar System were even confirmed to exist, it’s quite a milestone!
The milestone of 1,000 confirmed exoplanets was surpassed on October 22, 2013 after twenty-one years of discoveries. The long-established and well-known Extrasolar Planets Encyclopedia now lists 1,010 confirmed exoplanets.
Not all current exoplanet catalogs list the same numbers as this depends on their particular criteria. For example, the more recent NASA Exoplanet Archive lists just 919. Nevertheless, over 3,500 exoplanet candidates are waiting for confirmation.
The first confirmed exoplanets were discovered by the Arecibo Observatory in 1992. Two small planets were found around the remnants of a supernova explosion known as a pulsar. They were the surviving cores of former planets or newly formed bodies from the ashes of a dead star. This was followed by the discovery of exoplanets around sun-like stars in 1995 and the beginning of a new era of exoplanet hunting.
The milestone of 1,000 confirmed exoplanets was surpassed on October 22, 2013 after twenty-one years of discoveries. The long-established and well-known Extrasolar Planets Encyclopedia now lists 1,010 confirmed exoplanets.
Not all current exoplanet catalogs list the same numbers as this depends on their particular criteria. For example, the more recent NASA Exoplanet Archive lists just 919. Nevertheless, over 3,500 exoplanet candidates are waiting for confirmation.
The first confirmed exoplanets were discovered by the Arecibo Observatory in 1992. Two small planets were found around the remnants of a supernova explosion known as a pulsar. They were the surviving cores of former planets or newly formed bodies from the ashes of a dead star. This was followed by the discovery of exoplanets around sun-like stars in 1995 and the beginning of a new era of exoplanet hunting.
A “Periodic Table of Exoplanets” as listed by the Extrasolar Planets Encyclopedia (PHL)
Exoplanet discoveries have been full of surprises from the outset. Nobody expected exoplanets around the remnants of a dead star (i.e. PSR 1257+12), nor Jupiter-size orbiting close to their stars (i.e. 51 Pegasi). We also know today of stellar systems packed with exoplanets (i.e. Kepler-11), around binary stars (i.e. Kepler-16), and with many potentially habitable exoplanets (i.e. Gliese 667C).
But the milestone of discovering this many planets outside our solar system is just the first step in developing a clear understanding of the types of worlds that are out thereand how they work. Yesterday, in a press release announcing the milestone, professor Abel Mendez of the Planetary Habitability Laboratory at UPR Arecibo expressed his view of the work still left to do:
“The discovery of many worlds around others stars is a great achievement of science and technology. The work of scientists and engineers from many countries were necessary to achieve this difficult milestone. However, one thousand exoplanets in two decades is still a small fraction of those expected from the billions of stars in our galaxy. The next big goal is to better understand their properties, while detecting many new ones.”
While not illustrating the full 1,010 lineup, the still a mesmerizing visualization by Daniel Fabrycky of 885 planetary candidates in 361 systems as found by the Kepler mission is shown below. (I for one am looking forward to the third installment!)
But the milestone of discovering this many planets outside our solar system is just the first step in developing a clear understanding of the types of worlds that are out thereand how they work. Yesterday, in a press release announcing the milestone, professor Abel Mendez of the Planetary Habitability Laboratory at UPR Arecibo expressed his view of the work still left to do:
“The discovery of many worlds around others stars is a great achievement of science and technology. The work of scientists and engineers from many countries were necessary to achieve this difficult milestone. However, one thousand exoplanets in two decades is still a small fraction of those expected from the billions of stars in our galaxy. The next big goal is to better understand their properties, while detecting many new ones.”
While not illustrating the full 1,010 lineup, the still a mesmerizing visualization by Daniel Fabrycky of 885 planetary candidates in 361 systems as found by the Kepler mission is shown below. (I for one am looking forward to the third installment!)
Of course, scientists are still hunting for the “Holy Grail” of extrasolar planets: an Earth-sized, rocky world orbiting a Sun-like star within its habitable zone. But with new discoveries and confirmations happening almost every week, it’s now only a matter of time.
Comet ISON Alive and Well; Obscure Comet C/2012 X1 Bursts Into View
(October 22, 2013)
by Bob King, Astrobob.areavoices.com
Recent photos taken by the Hubble Space Telescope show that Comet ISON remains in one piece as it plunges ever closer to the sun. That’s good news. Had the nucleus broken into pieces, Hubble would have seen evidence for multiple fragments. While a splitting comet makes for fascinating observing it also spell its end. Each fragment fizzes away leaving a tail without a head.
We don’t want that to happen to Comet ISON. It would mean the end of our hopes for a great show after it passes closest to the sun on November 28.
We don’t want that to happen to Comet ISON. It would mean the end of our hopes for a great show after it passes closest to the sun on November 28.
Comet ISON on Oct. 9 photographed by the Hubble Space Telescope. The pressure of sunlight pushes dust particles released by vaporizing ice back to form the tail. The smooth and symmetric appearance to the comet’s head is another good sign that ISON remains intact. Credit: NASA / ESA
One change we CAN see in the Hubble photos is the disappearance of a bright jet of material streaming away from the nucleus. This fountain-like feature results from fresh ices, which contain dust and other materials, vaporizing from fissures or cracks in the icy body of the comet. Sunlight heats ice below the surface to form gas-filled cavities under pressure. When the gas finds a vent or passage to the surface, it erupts in a jet of material similar to air rushing from a balloon.
Comet ISON on April 10 showing the bright polar jet (fan at the comet’s front end) of fresh material expelled from the icy nucleus. Credit: NASA / ESA
Comparing the two Hubble pictures we can see that the dust jet is gone – perhaps it turned off temporarily. Photos taken by amateur astronomers, which have a much larger field of view than the Hubble, show an ever-lengthening tail. All these changes make watching comets a lot of fun.
At present, Comet ISON is still near Mars in the morning sky before dawn. Moonlight will compromise our view of the 10th magnitude “fuzzy glow” for about another week. Speaking of Mars, mission controllers attempted to photograph ISON with the Mars Opportunity Rover during its flyby earlier this month, but the comet was too faint to show in the rover’s panoramic camera. I still haven’t heard whether the Curiosity rover had better luck.
At present, Comet ISON is still near Mars in the morning sky before dawn. Moonlight will compromise our view of the 10th magnitude “fuzzy glow” for about another week. Speaking of Mars, mission controllers attempted to photograph ISON with the Mars Opportunity Rover during its flyby earlier this month, but the comet was too faint to show in the rover’s panoramic camera. I still haven’t heard whether the Curiosity rover had better luck.
Comet C/2012 X1 (LINEAR) experienced a bright outburst in the past couple days and will become an easy target in small telescopes as the moon wanes. This photo was taken earlier today Oct. 21. Click for more information. Credit: Ernesto Guido, Nick Howes and Martino Nicolini
Meanwhile, just a day ago, the obscure 14th magnitude comet C/2012 X1 (LINEAR) suddenly brightened nearly 200 times times to 8.5 magnitude.
Here’s a object very few people were paying attention to that’s now bright enough to spot in binoculars under a dark sky. The sudden flare may originate from a massive buildup of gas inside the comet that fractured and broke off a good-sized chunk of comet crust.
Here’s a object very few people were paying attention to that’s now bright enough to spot in binoculars under a dark sky. The sudden flare may originate from a massive buildup of gas inside the comet that fractured and broke off a good-sized chunk of comet crust.
Something similar happened to Comet Holmes in October 2007 when it brightened over half a million times from magnitude 17 to 2.8 over the space of only 42 hours. C/2012 X1 currently shines in Coma Berenices low in the dawn sky. It’s about 2′-3′ arc minutes across (less than 1/10 the diameter of the full moon) with a small, bright core. I’ve included a general finder map that shows the comet’s position and stars down to about 6th magnitude.
If X1 remains relatively bright, we’ll soon have four comets viewable in small telescopes by early November – Encke, ISON, Lovejoy and X1 LINEAR!
If X1 remains relatively bright, we’ll soon have four comets viewable in small telescopes by early November – Encke, ISON, Lovejoy and X1 LINEAR!
Closeup map showing the comet’s location on tomorrow morning Oct. 22 through Oct. 27. Use the star Beta and Alpha Coma Berenices as jumping off points. Stars shown to magnitude 9.0. Stellarium
How to See This Fall's Other Comet
(October 21, 2013)
by David Dickinson, www.UniverseToday.com
Comet 2P/Encke as imaged by Damian Peach on October 12th. Taken with a 20″ CDK telescope and a FLI Proline PL11002 Colr CCD camera; LRGB: L: 6×2 minutes, RGB exposure: 1×2 minutes. (Credit: D. Peach)
2013 may well go down as “The Year of the Comet.” After over a decade punctuated by only sporadic bright comets such as 17P/Holmes, C/2011 W3 Lovejoy and C/2006 P1 McNaught, we’ve already had two naked eye comets visible this year by way of C/2012 F6 Lemmon and C/2011 L4 PanSTARRS. And of course, all eyes are on Comet C/2012 S1 ISON as it plunges towards perihelion on U.S. Thanksgiving Day, November 28th.
But there’s an “old faithful” of comets that’s currently in our solar neighborhood, and worth checking out as well. Comet 2P/Encke (pronounced EN-key) currently shines at magnitude +7.9 and is crossing from the constellation Leo Minor into Leo this week. In fact, Encke is currently 2 magnitudes— over 6 times brighter than Comet ISON —and is currently the brightest comet in our skies. Encke is expected to top out at magnitude +7 right around perihelion towards the end of November. Encke will be a fine binocular object over the next month, and once the Moon passes Last Quarter phase on October 26th we’ll once again have a good three week window for pre-dawn comet hunting. Comet Encke made its closest pass of the Earth for this orbit on October 17th at 0.48 Astronomical Units (A.U.s) distant. This month sees its closest passage to the Earth since 2003, and the comet won’t pass closer until July 11th, 2030.
But there’s an “old faithful” of comets that’s currently in our solar neighborhood, and worth checking out as well. Comet 2P/Encke (pronounced EN-key) currently shines at magnitude +7.9 and is crossing from the constellation Leo Minor into Leo this week. In fact, Encke is currently 2 magnitudes— over 6 times brighter than Comet ISON —and is currently the brightest comet in our skies. Encke is expected to top out at magnitude +7 right around perihelion towards the end of November. Encke will be a fine binocular object over the next month, and once the Moon passes Last Quarter phase on October 26th we’ll once again have a good three week window for pre-dawn comet hunting. Comet Encke made its closest pass of the Earth for this orbit on October 17th at 0.48 Astronomical Units (A.U.s) distant. This month sees its closest passage to the Earth since 2003, and the comet won’t pass closer until July 11th, 2030.
This will be Comet Encke’s 62nd observed perihelion passage since its discovery by Pierre Méchain in 1786. Encke has the shortest orbit of any known periodic comet, at just 3.3 years. About every 33 years we get a favorable close pass of the comet, as last occurred in 1997, and will next occur in 2030.
But this year’s apparition of Comet Encke is especially favorable for northern hemisphere observers. This is due to its relatively high orbital inclination angle of 11.8 degrees and its passage through the morning skies from north of both the ecliptic and the celestial equator. Encke is about half an A.U. ahead of us in our orbit this month, crossing roughly perpendicular to our line of sight.
Note that Encke is also running nearly parallel to Comet ISON from our vantage point as they both make the plunge through the constellation Virgo into next month. Mark your calendars: both ISON and Encke will fit into a telescopic wide field of view around November 24th in the early dawn. Photo-op!
But this year’s apparition of Comet Encke is especially favorable for northern hemisphere observers. This is due to its relatively high orbital inclination angle of 11.8 degrees and its passage through the morning skies from north of both the ecliptic and the celestial equator. Encke is about half an A.U. ahead of us in our orbit this month, crossing roughly perpendicular to our line of sight.
Note that Encke is also running nearly parallel to Comet ISON from our vantage point as they both make the plunge through the constellation Virgo into next month. Mark your calendars: both ISON and Encke will fit into a telescopic wide field of view around November 24th in the early dawn. Photo-op!
The orbital path of Comet 2P/Encke. (Credit: The NASA/JPL Solar System Dynamics Small-Body Database Browser).
Here are some key dates to help you in your morning quest for Comet Encke over the next month:
-October 22nd: Crosses into the constellation Leo.
-October 24th: Passes near the +5.3 magnitude star 92 Leonis.
-October 25th: Passes near the +4.5 magnitude star 93 Leonis.
-October 27th: Passes briefly into the constellation Coma Berenices.
-October 29th: Passes near the +11th magnitude galaxy M98, and crosses into the constellation Virgo.
-October 30th: Passes near the +10th magnitude galaxy pair of M84 & M86.-November 2nd: Passes between the two +5th magnitude stars of 31 and 32 Virginis.
-November 3rd: A hybrid solar eclipse occurs across the Atlantic and central Africa. It may just be possible to spot comet Encke with binoculars during the brief moments of totality.
-November 4th: Passes near the +3.4 magnitude star Auva (Delta Virginis).
-November 7th: Crosses from north to south over the celestial equator.
-November 11th: Passes near the +5.7th star 80 Virginis.
-November 17th: The Moon reaches Full, and enters into the morning sky.
-November 18th: Passes 0.02 A.U. (just under 3 million kilometers, or 7.8 Earth-Moon distances) from the planet Mercury. A good chance for NASA’s Messenger spacecraft to perhaps snap a pic of the comet?
-November 19th: Passes 1.5 degrees from Mercury and crosses into the constellation Libra.
-November 20th: Crosses to the south of the ecliptic plane.
-November 21st: Reaches perihelion, at 0.33 AU from the Sun.
-November 24th: Comet Encke passes just 1.25 degrees from Comet ISON. Both will have a western elongation of 15 degrees from the Sun.
-November 26th: Passes near the +4.5 magnitude star Iota Librae and the +6th magnitude star 25 Librae.
-December 1st: Crosses into the constellation Scorpius.
-December 5th: Enters into view of SOHO’s LASCO C3 camera.
Note: “Passes near” on the above list indicates a passage of Comet Encke less than one angular degree (about twice the size of a Full Moon) from an interesting object, except where noted otherwise.
Binoculars are your best bet for catching sight of Comet 2P/Encke. For middle northern latitude observers, Comet Encke reaches an elevation above 20 degrees from the horizon about two hours before local sunrise. Keep in mind, Europe and the U.K. “fall back” an hour to Standard Time this coming weekend on October 27th, and most of North America follows suit on November 3rd, pushing the morning comet vigil back an hour as well.
-October 22nd: Crosses into the constellation Leo.
-October 24th: Passes near the +5.3 magnitude star 92 Leonis.
-October 25th: Passes near the +4.5 magnitude star 93 Leonis.
-October 27th: Passes briefly into the constellation Coma Berenices.
-October 29th: Passes near the +11th magnitude galaxy M98, and crosses into the constellation Virgo.
-October 30th: Passes near the +10th magnitude galaxy pair of M84 & M86.-November 2nd: Passes between the two +5th magnitude stars of 31 and 32 Virginis.
-November 3rd: A hybrid solar eclipse occurs across the Atlantic and central Africa. It may just be possible to spot comet Encke with binoculars during the brief moments of totality.
-November 4th: Passes near the +3.4 magnitude star Auva (Delta Virginis).
-November 7th: Crosses from north to south over the celestial equator.
-November 11th: Passes near the +5.7th star 80 Virginis.
-November 17th: The Moon reaches Full, and enters into the morning sky.
-November 18th: Passes 0.02 A.U. (just under 3 million kilometers, or 7.8 Earth-Moon distances) from the planet Mercury. A good chance for NASA’s Messenger spacecraft to perhaps snap a pic of the comet?
-November 19th: Passes 1.5 degrees from Mercury and crosses into the constellation Libra.
-November 20th: Crosses to the south of the ecliptic plane.
-November 21st: Reaches perihelion, at 0.33 AU from the Sun.
-November 24th: Comet Encke passes just 1.25 degrees from Comet ISON. Both will have a western elongation of 15 degrees from the Sun.
-November 26th: Passes near the +4.5 magnitude star Iota Librae and the +6th magnitude star 25 Librae.
-December 1st: Crosses into the constellation Scorpius.
-December 5th: Enters into view of SOHO’s LASCO C3 camera.
Note: “Passes near” on the above list indicates a passage of Comet Encke less than one angular degree (about twice the size of a Full Moon) from an interesting object, except where noted otherwise.
Binoculars are your best bet for catching sight of Comet 2P/Encke. For middle northern latitude observers, Comet Encke reaches an elevation above 20 degrees from the horizon about two hours before local sunrise. Keep in mind, Europe and the U.K. “fall back” an hour to Standard Time this coming weekend on October 27th, and most of North America follows suit on November 3rd, pushing the morning comet vigil back an hour as well.
The celestial path of Comet 2P/Encke from October 20th to 20 November 20th. Note that ISON is very near Encke on the final date. Click on the image to enlarge. (Created using Starry Night Education Software).
Two other comets are both currently brighter than ISON and also merit searching for: Comet C/2013 R1 Lovejoy, at +8.7th magnitude in Canis Minor, and Comet C/2012 X1 LINEAR, currently also in Coma Berenices and undergoing a minor outburst at magnitude +8.5.
Be sure to check these celestial wonders out as we prepare for the “Main Event” of Comet ISON in November 2013!
Be sure to check these celestial wonders out as we prepare for the “Main Event” of Comet ISON in November 2013!
Orionids Still Active (October 21, 2013)
Earth is passing through a stream of debris from Halley's Comet, source of the annual Orionid meteor shower. Last night NASA's All-Sky Fireball Network detected 15 Orionid fireballs over the United States. After sunrise, the Canadian Meteor Orbit Radar (CMOR) continued to record echoes from Orionids in broad daylight. This CMOR sky map shows the Orionid radiant (ORI) clearly active at 1445 UT on Oct. 21st:
Forecasters expect the shower to peak on Oct. 21st with about 20 meteors per hour. However, Halley's debris stream is broad, so Orionid activity could spill into Oct. 22nd. The best time to look is during the hours before local sunrise when the constellation Orion is high in the sky. [meteor radar] [sky map]
New Champion Star Crowned Largest In the Milky Way Galaxy (October 20, 2013)
The largest star ever discovered may give scientists a better sense of how massive, dying stars seed the universe with the ingredients for rocky planets and even life.
Westerlund 1-26 (also known as W26 and Westerlund 1 BKS AS) is a red supergiant or hypergiant star within the outskirts of the Westerlund 1 super star cluster. It is definitely one of the largest known stars, an extreme red supergiant otherwise known as a red "hypergiant" star. A recent study by by astronomers using the VST in Chile has found that W26 is approximately 1,530 times the radius of our Sun (up to 2,544 by some earlier estimates). This makes it the largest star in size in the Milky Way galaxy. Also noted in the study, scientists report that due to the star's observed increasing instability, it will soon die in a core collapse supernova.
"Stars with masses tens of times larger than that of the sun live very short and dramatic lives compared to their less massive siblings," officials with the Royal Astronomical Society (RAS) in the U.K. said in a statement. "Some of the most massive stars have lifetimes of less than a few million years before they exhaust their nuclear fuel and explode as supernovas. At the very ends of their lives these stars become highly unstable and eject a considerable amount of material from their outer envelopes."
Westerlund 1-26 (also known as W26 and Westerlund 1 BKS AS) is a red supergiant or hypergiant star within the outskirts of the Westerlund 1 super star cluster. It is definitely one of the largest known stars, an extreme red supergiant otherwise known as a red "hypergiant" star. A recent study by by astronomers using the VST in Chile has found that W26 is approximately 1,530 times the radius of our Sun (up to 2,544 by some earlier estimates). This makes it the largest star in size in the Milky Way galaxy. Also noted in the study, scientists report that due to the star's observed increasing instability, it will soon die in a core collapse supernova.
"Stars with masses tens of times larger than that of the sun live very short and dramatic lives compared to their less massive siblings," officials with the Royal Astronomical Society (RAS) in the U.K. said in a statement. "Some of the most massive stars have lifetimes of less than a few million years before they exhaust their nuclear fuel and explode as supernovas. At the very ends of their lives these stars become highly unstable and eject a considerable amount of material from their outer envelopes."
HD 184738, also known as Campbell’s hydrogen star. This supergiant star is known to have such enormously strong stellar winds that the star is losing a significant portion of its mass as it casts off its outer layers. This happens rarely in large stars, lasting only a short time as the star prepares to detonate in a supernova explosion.
Astronomers were using the European Southern Observatory's Very Large Telescope Survey Telescope (VST) in Chile to study the largest star cluster in the Milky Way galaxy, a collection of several hundred thousand stars about 16,000 light-years from Earth known as Westerlund 1.
From previous studies of the star, scientists have known that it is extremely cool for a star, with an average "surface" temperature of only about 3000 degrees. Stars this cool actually emit most of their energy in the infrared portion of the spectrum. As they peered at W26, which lies within Westerlund 1, the team noticed something odd: The gigantic star is surrounded by a big, glowing cloud of hydrogen gas.
Now, it is not that unusual to find a cloud of gas like this surrounding blue hypergiant-type stars. A number of these stars have been discovered in recent years and some have been seen throwing off copious amounts of their own atmospheres in a type of super stellar wind in a phase of their short lives known as the Wolf-Rayet stage. What is unusual in the case of W26 is that its giant cloud of hydrogen is being forced to glow by ionizing radiation around such a cool red supergiant star.
"W26 itself would be too cool to make the gas glow; the astronomers speculate that the source of the ionizing radiation may be either hot blue stars elsewhere in the cluster, or possibly a fainter, but much hotter, companion star to W26", RAS officials said. "The fact that the nebula is ionized will make it considerably easier to study in the future than if it were not ionized."
Being that this is the first "ionized nebula" ever found around a red supergiant, the study of this cloud will provide scientists with a new way to study how W26 and other stars like it slough off their layers before possibly going supernova, shooting material into the interstellar medium, RAS officials said.
From previous studies of the star, scientists have known that it is extremely cool for a star, with an average "surface" temperature of only about 3000 degrees. Stars this cool actually emit most of their energy in the infrared portion of the spectrum. As they peered at W26, which lies within Westerlund 1, the team noticed something odd: The gigantic star is surrounded by a big, glowing cloud of hydrogen gas.
Now, it is not that unusual to find a cloud of gas like this surrounding blue hypergiant-type stars. A number of these stars have been discovered in recent years and some have been seen throwing off copious amounts of their own atmospheres in a type of super stellar wind in a phase of their short lives known as the Wolf-Rayet stage. What is unusual in the case of W26 is that its giant cloud of hydrogen is being forced to glow by ionizing radiation around such a cool red supergiant star.
"W26 itself would be too cool to make the gas glow; the astronomers speculate that the source of the ionizing radiation may be either hot blue stars elsewhere in the cluster, or possibly a fainter, but much hotter, companion star to W26", RAS officials said. "The fact that the nebula is ionized will make it considerably easier to study in the future than if it were not ionized."
Being that this is the first "ionized nebula" ever found around a red supergiant, the study of this cloud will provide scientists with a new way to study how W26 and other stars like it slough off their layers before possibly going supernova, shooting material into the interstellar medium, RAS officials said.
A new photo of W26 and Westerlund 1 shows the ionized nebula glowing green, standing out in a blanket of stars. Despite its size, the cluster looks somewhat dim because gas and dust obscure its view in visible light from Earth.
The VST instrument was able to peer through that cosmic haze to investigate the star cluster and W26. The new research is detailed in the Monthly Notices of the Royal Astronomical Society.
The VST instrument was able to peer through that cosmic haze to investigate the star cluster and W26. The new research is detailed in the Monthly Notices of the Royal Astronomical Society.
Orionid Meteor Shower Peak to Be Weakened by Moonshine (October 19, 2013)
by Joe Rao, www.space.com
A lone Orionid streaks down along the winter Milky Way during last year's shower. The Orionid shower is the first major meteor shower in a stretch of several that run almost continuously from mid-October through mid-December. Photo by Bill Vaughn.
Cosmic litter from Halley's Comet is set to pepper the night sky in a meteor shower before dawn this weekend and early next week.
The Orionid meteor shower can best be described as a lesser version of the famous Perseid meteor shower of August. The October shower is scheduled to reach its maximum before sunrise on Monday morning (Oct. 21). The meteors are known as "Orionids" because they seem to fan out from a region to the north of Orion's second brightest star, the ruddy hued Betelgeuse.
Currently, Orion appears ahead of Earth in the planet's journey around the sun. The constellation does not completely rise above the eastern horizon until after 11:30 p.m. local daylight time.
The Orionid meteor shower can best be described as a lesser version of the famous Perseid meteor shower of August. The October shower is scheduled to reach its maximum before sunrise on Monday morning (Oct. 21). The meteors are known as "Orionids" because they seem to fan out from a region to the north of Orion's second brightest star, the ruddy hued Betelgeuse.
Currently, Orion appears ahead of Earth in the planet's journey around the sun. The constellation does not completely rise above the eastern horizon until after 11:30 p.m. local daylight time.
The Orionids are a reliable if minor meteor shower that returns every year in late October. Despite moonlight, keep watch for the occasional bright Orionid shooting from above the constellation Orion near the bright planet Jupiter on the mornings of Oct. 21 and 22. This map shows the sky facing south around 5-5:30 a.m local time. Stellarium
At its best during the predawn hours around 5 a.m. EDT (0900 GMT) — Orion will be highest in the sky toward the south — the Orionids typically produce around 20 to 25 meteors per hour under a clear, dark sky. This shower is one of just a handful of known meteor showers that can be observed equally well from both the Northern and Southern Hemispheres.
Usually Orionid meteors are normally dim and not well seen from urban locations, so it's suggested that you find a safe, rural location to see the best Orionid activity.
Orionid activity tends to noticeably ramp-up by around Oct. 17 when they start appearing at roughly five per hour. The shower may be quite active for several days before or after its broad maximum, which may last from Oct. 19 through Oct. 23. After peaking on the morning of Oct. 21, activity will begin to slowly descend, dropping back to around five per hour around Oct. 25. The last stragglers usually appear sometime in early to mid November.
The Moon 'Muscles In'
Unfortunately, 2013 is a poor year for the Orionids thanks to the moon, which turns full on Oct. 18.
On the morning of the Orionid maximum on Monday the meteor shower will share the sky with the brilliant light of a 94 percent illuminated gibbous moon. Although the Orionids will be at their peak, most of meteors will likely be obliterated by the bright moonlight.
If the moon, weather or poor timing obstructs your view of the meteor shower, you can also catch sight of the Orionids online. The online Slooh Space Camera will host live views of the meteor shower from the Canary Islands off the coast of West Africa on Oct. 20. The broadcast begins at 8 p.m. EDT (0000 Oct. 21 GMT) and you can watch the Orionid webcast on SPACE.com courtesy of Slooh.
Still, an exceptionally bright Orionid, darting from out of Orion's region might still be glimpsed.
Usually Orionid meteors are normally dim and not well seen from urban locations, so it's suggested that you find a safe, rural location to see the best Orionid activity.
Orionid activity tends to noticeably ramp-up by around Oct. 17 when they start appearing at roughly five per hour. The shower may be quite active for several days before or after its broad maximum, which may last from Oct. 19 through Oct. 23. After peaking on the morning of Oct. 21, activity will begin to slowly descend, dropping back to around five per hour around Oct. 25. The last stragglers usually appear sometime in early to mid November.
The Moon 'Muscles In'
Unfortunately, 2013 is a poor year for the Orionids thanks to the moon, which turns full on Oct. 18.
On the morning of the Orionid maximum on Monday the meteor shower will share the sky with the brilliant light of a 94 percent illuminated gibbous moon. Although the Orionids will be at their peak, most of meteors will likely be obliterated by the bright moonlight.
If the moon, weather or poor timing obstructs your view of the meteor shower, you can also catch sight of the Orionids online. The online Slooh Space Camera will host live views of the meteor shower from the Canary Islands off the coast of West Africa on Oct. 20. The broadcast begins at 8 p.m. EDT (0000 Oct. 21 GMT) and you can watch the Orionid webcast on SPACE.com courtesy of Slooh.
Still, an exceptionally bright Orionid, darting from out of Orion's region might still be glimpsed.
A spectacular Orionid fireball was witnessed by hundreds of unsuspecting bystanders in the San Francisco Bay area last year on the night of the peak of the meteor shower.
"They are easily identified . . . from their speed," write David Levy and Stephen Edberg in Observe: Meteors, an Astronomical League manual. "At 66 kilometers (41 miles) per second, they appear as fast streaks, faster by a hair than their sisters, the Eta Aquarids of May. And like the Eta Aquarids, the brightest of this family tend to leave long-lasting trains."
Indeed, recent studies have shown that about half of all spotted Orionids leave trails that lasted longer than other meteors of equivalent brightness.
Halley's legacy
The Orionids are the legacy of the famous Halley's Comet.
Comets are leftover pieces that date back to the formation of the solar system. The "dirty snowballs" are the odd bits and pieces of simple gases — methane, ammonia, carbon dioxide and water vapor — that went unused when the sun and its attendant planets came into their present form.
Meteoroids released into space out of cometary debris are the remnants of a comet's nucleus. All comets eventually disintegrate into meteor swarms and Halley's is well into that process at this time.
Tiny particles — mostly ranging in size from dust to sand grains — remain along the original comet's orbit, creating a "river of rubble" in space.
Indeed, recent studies have shown that about half of all spotted Orionids leave trails that lasted longer than other meteors of equivalent brightness.
Halley's legacy
The Orionids are the legacy of the famous Halley's Comet.
Comets are leftover pieces that date back to the formation of the solar system. The "dirty snowballs" are the odd bits and pieces of simple gases — methane, ammonia, carbon dioxide and water vapor — that went unused when the sun and its attendant planets came into their present form.
Meteoroids released into space out of cometary debris are the remnants of a comet's nucleus. All comets eventually disintegrate into meteor swarms and Halley's is well into that process at this time.
Tiny particles — mostly ranging in size from dust to sand grains — remain along the original comet's orbit, creating a "river of rubble" in space.
In the case of Halley's comet (which has likely circled the sun many hundreds, if not thousands of times), its dirty trail of debris has been distributed more or less uniformly all along its entire orbit. When these tiny bits of comet collide with Earth, friction with our atmosphere raises them to white heat and produces the effect popularly referred to as "shooting stars."
The orbit of Halley's Comet closely approaches the Earth's orbit at two places. Therefore, the debris creates two meteor showers: the Orionids in October and the Eta Aquarids in May.
Step outside before sunrise this weekend or early next week, and if you catch sight of a meteor, there's about a 75 percent chance that it likely originated from the nucleus of Halley's Comet.
The orbit of Halley's Comet closely approaches the Earth's orbit at two places. Therefore, the debris creates two meteor showers: the Orionids in October and the Eta Aquarids in May.
Step outside before sunrise this weekend or early next week, and if you catch sight of a meteor, there's about a 75 percent chance that it likely originated from the nucleus of Halley's Comet.
Huge Meteorite Pulled from Russian Lake (October 18, 2013)
by Kelly Beatty, www.skyandtelescope.com
After an 8-month salvage effort, today divers finally brought a half-ton fragment of the Chelyabinsk meteorite up from the murky bottom of Russia's Lake Chebarkul and onto dry land.
After the Chelyabinsk blast, local officials were directed to this fresh hole in the thick ice covering Lake Chebarkul, about 45 miles (70 km) west of the city. Some evidence suggests that a large fragment of the meteorite created the 25-foot (8-m) hole when it plunged through the ice and now lies in pieces on the lake's murky bottom.
Andrey Orlov / RT.com
Soon after a mini-asteroidroared over Chelyabinsk, Russia, on February 15th, locals discovered a 25-foot (8-m) hole in the ice covering Lake Chebarkul. The lake is about 45 miles (70 km) west of Chelyabinsk, and for 8 months meteorite researchers (and collectors) around the world have wondered whether one or more massive fragments ended up on the lake's murky bottom.
Just a few weeks after the once-in-a-century event, researchers from nearby Ural Federal University released a tantalizing magnetometer scan hinting that something big was down there, but the months afterward brought only vague or unsubstantiated reports that an object up to 20 feet across had been located.
Just a few weeks after the once-in-a-century event, researchers from nearby Ural Federal University released a tantalizing magnetometer scan hinting that something big was down there, but the months afterward brought only vague or unsubstantiated reports that an object up to 20 feet across had been located.
After planning its extraction for 8 months, divers finally retrieved a half-ton chunk of stone — likely a fragment of the Chelyabinsk mini-asteroid — from the bottom of Lake Chebarkul on October 16, 2013.
BBC
The waiting ended today, when a team of divers and researchers removed a 5-foot long stone from the lake bottom and dragged it onto the shore. Although tests haven't yet confirmed that it truly is a piece of the Chelyabinsk impactor, the giant rock sure looks the part. members of the recovery team attempted to weigh it, but their scale broke during the measurement. The last reading was 570 kg (1,250 pounds).
Reporters on the scene say the stone broke into three pieces (apparently along known fractures). But there wasn't much time for inspection, as Russian researchers bundled up the fragments and whisked them away after about 10 minutes of show 'n' tell.
"It’s a typical meteorite, judging by its appearance," Viktor Grokhovsky (Ural Federal University) told a reporter for RIA Novosti. "There's no doubt about that." Grokhovsky says the stone has a thick melted crust and other characteristics typical of pieces of the Chelyabinsk meteorite.
The magnetometer survey suggested that multiple masses lie at the bottom of Lake Chebarkul. A second fragment, with an estimated mass of 300 to 500 kg, was scheduled to be pulled out later today, but there's been no confirmation yet. In that location, the lake bottom is about 35 feet (10 m) deep and covered by a thick layer of silt.
Reporters on the scene say the stone broke into three pieces (apparently along known fractures). But there wasn't much time for inspection, as Russian researchers bundled up the fragments and whisked them away after about 10 minutes of show 'n' tell.
"It’s a typical meteorite, judging by its appearance," Viktor Grokhovsky (Ural Federal University) told a reporter for RIA Novosti. "There's no doubt about that." Grokhovsky says the stone has a thick melted crust and other characteristics typical of pieces of the Chelyabinsk meteorite.
The magnetometer survey suggested that multiple masses lie at the bottom of Lake Chebarkul. A second fragment, with an estimated mass of 300 to 500 kg, was scheduled to be pulled out later today, but there's been no confirmation yet. In that location, the lake bottom is about 35 feet (10 m) deep and covered by a thick layer of silt.
A map of the magnetic field measured at the bottom of Lake Chebarkul. The area shown measures 100 by 60 meters. Red areas might indicate the location of large fragments of the Cherbakul meteorite, which fell in countless pieces across the region on February 15, 2013.
Ural Federal University
Earlier this year, Svend Buhl and Karl Wimmer painstakingly documented the locations of hundreds of smaller fragments scattered in an elongated strewnfield 45 miles long and 12 wide (70 by 20 km). They predicted that the most massive object, the one that fell in the lake, would weigh in at roughly 700 pounds (300 kg).
The Chelyabinsk impactor had an estimated diameter of about 54 feet (17 m) and a mass of roughly 10,000 metric tons. The vast majority of it was likely vaporized and pulverized to dust when it slammed into the atmosphere and released the kinetic energy equivalent of 470,000 tons of TNT, 30 times the explosive power of the Hiroshima bomb.
Two good videos showing the recovery are available online from the BBC (in English) and the CBC (sound but no commentary). For the truly captivated, there's an hour-long video here.
The Chelyabinsk impactor had an estimated diameter of about 54 feet (17 m) and a mass of roughly 10,000 metric tons. The vast majority of it was likely vaporized and pulverized to dust when it slammed into the atmosphere and released the kinetic energy equivalent of 470,000 tons of TNT, 30 times the explosive power of the Hiroshima bomb.
Two good videos showing the recovery are available online from the BBC (in English) and the CBC (sound but no commentary). For the truly captivated, there's an hour-long video here.
Live: Penumbral Lunar Eclipse Tonight (October 18, 2013)
The full moon will dip into Earth's shadow tonight (Oct. 18), producing a lunar eclipse that can be seen by keen observers around the world.
Weather permitting, skywatchers in Africa, Europe, western Asia, and the eastern parts of North and South America will get the chance to observe part of the southern portion of the moon passing into Earth's penumbra — the planet's outer shadow. The shading will be subtle, but during the
penumbral lunar eclipse, the moon will be partially in shadow for about four hours with the time of deepest eclipse occurring at 7:50 p.m. EDT (2350 GMT) when 76% of the disk will be in the Earth's outer shadow.
Eclipse Online
You can also watch the eclipse online. The online Slooh Space Camera will air a live broadcast of the entire four-hour eclipse starting at 2:45 p.m. EDT (1845 GMT). Slooh's team of experts will join the show at 7:30 p.m. EDT (2330 GMT) to comment during the eclipse's peak. You can watch the penumbral eclipse live, courtesy of Slooh.com.
Weather permitting, skywatchers in Africa, Europe, western Asia, and the eastern parts of North and South America will get the chance to observe part of the southern portion of the moon passing into Earth's penumbra — the planet's outer shadow. The shading will be subtle, but during the
penumbral lunar eclipse, the moon will be partially in shadow for about four hours with the time of deepest eclipse occurring at 7:50 p.m. EDT (2350 GMT) when 76% of the disk will be in the Earth's outer shadow.
Eclipse Online
You can also watch the eclipse online. The online Slooh Space Camera will air a live broadcast of the entire four-hour eclipse starting at 2:45 p.m. EDT (1845 GMT). Slooh's team of experts will join the show at 7:30 p.m. EDT (2330 GMT) to comment during the eclipse's peak. You can watch the penumbral eclipse live, courtesy of Slooh.com.
Jupiter's Moons Do Double Transit Dance
(October 17, 2013)
A solar eclipse happens when a moon casts its shadow on the planet below it. For observers located where the shadow falls, the sun appears to be completely blocked by the moon. Sometimes, skywatchers can even see the prominences and corona around the occluding moon.
In the Earth-moon system, the moon's orbit is tilted with respect to the sun and the Earth is a fairly small target with the moon being relatively far away, so it's rare for the moon's shadow to fall on the Earth. On average it happens about twice a year, and the diameter of the shadow on the Earth's surface is quite small, only a couple of hundred miles. To see a solar eclipse, you need to be in exactly the right place, where the moon's shadow falls. The next eclipse of the Sun on Earth's surface will happen on Nov. 3rd.
Because the moon's orbit is tilted with respect to the Earth, most of the time the moon's shadow passes above or below the Earth, and no eclipse occurs.
With Jupiter, the situation is different. Jupiter has four large moons: Io, Europa, Ganymede and Callisto. These are relatively close to Jupiter and the gas giant is much larger than Earth.
As a result, the shadows of Jupiter's moons cross its face very frequently. The innermost moon, Io causes an eclipse on Jupiter once every 1.8 days (42 hours). Even the outermost moon, Callisto, traveling much more slowly, should cause an eclipse every 17 days, but it does so less frequently because, like our moon, sometimes its shadow passes above or below Jupiter.
In the Earth-moon system, the moon's orbit is tilted with respect to the sun and the Earth is a fairly small target with the moon being relatively far away, so it's rare for the moon's shadow to fall on the Earth. On average it happens about twice a year, and the diameter of the shadow on the Earth's surface is quite small, only a couple of hundred miles. To see a solar eclipse, you need to be in exactly the right place, where the moon's shadow falls. The next eclipse of the Sun on Earth's surface will happen on Nov. 3rd.
Because the moon's orbit is tilted with respect to the Earth, most of the time the moon's shadow passes above or below the Earth, and no eclipse occurs.
With Jupiter, the situation is different. Jupiter has four large moons: Io, Europa, Ganymede and Callisto. These are relatively close to Jupiter and the gas giant is much larger than Earth.
As a result, the shadows of Jupiter's moons cross its face very frequently. The innermost moon, Io causes an eclipse on Jupiter once every 1.8 days (42 hours). Even the outermost moon, Callisto, traveling much more slowly, should cause an eclipse every 17 days, but it does so less frequently because, like our moon, sometimes its shadow passes above or below Jupiter.
So, if eclipses on Jupiter happen very often, why don't we see more of them?
The timing has to be exactly right. Io may cause an eclipse on Jupiter every 42 hours, but the eclipse itself lasts only a little over two hours. Also, Io's shadow is very small; you need a telescope with at least 90mm aperture to see it. If you aren't looking for it, you probably wouldn't see it at all. Also, because of the Earth's rotation, Jupiter is below the horizon half the time, and often lost in the daylight sky.
If the shadows of its moons fall so often on Jupiter, what are the chances of two shadows falling simultaneously? Pretty good, it turns out. This is especially true because there is a resonance between the orbits of Jupiter's moons. Europa's period of revolution is almost exactly twice that of Io, and Ganymede's almost exactly four times. Only Callisto doesn't keep step with the inner satellites.
As a result, double shadow transits usually happen in a group. The current group started with a double transit of Io and Europa's shadows on September 28 and will continue every few days until Nov. 13.
The timing has to be exactly right. Io may cause an eclipse on Jupiter every 42 hours, but the eclipse itself lasts only a little over two hours. Also, Io's shadow is very small; you need a telescope with at least 90mm aperture to see it. If you aren't looking for it, you probably wouldn't see it at all. Also, because of the Earth's rotation, Jupiter is below the horizon half the time, and often lost in the daylight sky.
If the shadows of its moons fall so often on Jupiter, what are the chances of two shadows falling simultaneously? Pretty good, it turns out. This is especially true because there is a resonance between the orbits of Jupiter's moons. Europa's period of revolution is almost exactly twice that of Io, and Ganymede's almost exactly four times. Only Callisto doesn't keep step with the inner satellites.
As a result, double shadow transits usually happen in a group. The current group started with a double transit of Io and Europa's shadows on September 28 and will continue every few days until Nov. 13.
Image of double shadow transit of Ganymede and Io back on Jan 3rd of this year. Several of these shadow/moon transit events are happening in the next few weeks. Stay tuned for follow up information. Image by Damien Peach.
The rarest of all shadow transit events is when three shadows cross Jupiter's face simultaneously, and this happened last Friday night (Oct. 11). If you missed this event, there will be two double shadow transits this month visible over most of North America starting tomorrow night (Oct. 18 to 19, and on the night of the 25/26th. In each case, the events mostly occur after Jupiter rises around midnight on the first date, so that's the night you should mark on your calendar. Remember that the date changes at midnight. Here is some information about each of these events:
- Friday/Saturday, Oct 18/19 - Dbl Sh Tr/ Dbl Trans of Jup
- - Time: 02:00AM EDT
- Double shadow transit of Jupiter:
02:00 Sh Tr Start Europa
02:25 Sh Tr Start Io (Dbl Sh Tr Start)
03:41 Tr Start Io
05:37 Sh Tr End Europa (Dbl Sh Tr End)
05:37 Tr Start Europa (Dbl Moon Tr Start)
04:38 Sh Tr End Io
05:54 Tr End Io 07:17 Tr End Europa (Dbl Moon Tr End) - Friday/Saturday, Oct 25/26 - Dbl Sh Tr / Dbl Trans of Jup-Time: 04:18AM EDT
- Double shadow transit and double transit of Jupiter:
- 04:18 Sh Tr Start Io
04:37 Sh Tr Start Europa (Dbl Sh Tr Start)
05:32 Tr Start Io
06:31 Sh Tr End Io (Dbl Sh Tr End)
07:10 Tr Start Europa (Dbl Tr Start)
07:14 Sh Tr End Europa
07:46 Tr End Io (Dbl Tr End)
09:50 Tr End Europa
Conjunction of Venus and Antares Tonight (October 16, 2013)
Over the last several weeks, Venus and red supergiant star Antares have slowly been approaching one another as they appear in the western sky just after sunset. Tonight, they make their closest approach in the sky for this seasonal apparition of Venus, appearing only 1.5 degrees apart with Venus above the twinkling orange-red star. Of course, this close apparition is only due to the alignment of these two objects in our skies because of the planets' movements around the sun. Antares, the 16th brightest star in the night sky ( at magnitude +1.09) is some 604 light-years away. Yet it still should be easy to spot in the deepening twilight shortly after sunset. The colour contrast between the planet and the star should be an interesting sight to even the unaided eye.
For a little more challenge, try locating the planets Saturn and Mercury which both lie low to the northwest (right and a little lower than the pair). Mercury in particular should be quite challenging as at this particular time in its apparition it is very low, visible just above the horizon (4 degrees) about a half-hour after sunset. To find both planets you'll need a clear horizon and probably a pair of binoculars to see Mercury.
For a little more challenge, try locating the planets Saturn and Mercury which both lie low to the northwest (right and a little lower than the pair). Mercury in particular should be quite challenging as at this particular time in its apparition it is very low, visible just above the horizon (4 degrees) about a half-hour after sunset. To find both planets you'll need a clear horizon and probably a pair of binoculars to see Mercury.
Easy Way to Find Comet ISON
(October 15, 2013)
How do you find Comet ISON? Wake up before dawn, face east, and follow the "double star." Rising about three hours before the sun, red Mars and blue-white Regulus have converged to form a bright pair separated by only 1o. Martin Gembec photographed the duo from the Czech Republic before daybreak on Oct. 14th.
To find Comet ISON, take a look at the full-sized image. The comet is just above Mars. By the way, can you make out the tiny fuzzy patch just above the glow of Regulus, slightly to the left of the center of the star? Martin also managed to capture the faint glow of one of our Milky Way galaxies faint neighbours - dwarf galaxy Leo I.
On Nov. 28th, Comet ISON could become spectacularly bright when it flies through the atmosphere of the sun. At the moment, though, it is still far away (near Mars) and faint. Visibility requires a telescope. Amateur astronomers, if you have a GOTO telescope, enter these coordinates, or just find the "double star" and draw a line between Regulus and Mars. It leads to ISON. Sky map: Oct. 15.
On Nov. 28th, Comet ISON could become spectacularly bright when it flies through the atmosphere of the sun. At the moment, though, it is still far away (near Mars) and faint. Visibility requires a telescope. Amateur astronomers, if you have a GOTO telescope, enter these coordinates, or just find the "double star" and draw a line between Regulus and Mars. It leads to ISON. Sky map: Oct. 15.
Penumbral Lunar Eclipse on October 18
(October 15, 2013) by Alan MacRobert, skyandtelescope.com
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On the evening of Friday, October 18th, the full Moon will glide across the pale outer fringe (penumbra) of Earth's shadow. Mid-eclipse occurs at 23:50 UT (7:50 p.m. Eastern Daylight Time), when the Moon's southern limb will be a quarter of a lunar diameter away from the unseen edge of Earth's umbra, the dark core of its shadow. This means that for most eastern and midwestern observers in North America that the eclipse will be well underway as the moon rises in the east at sunset. However, it should still be interesting to see the subtle changes in shading as the eclipse progresses from maximum to its waning moments.
Unusual shading on the southern half of the Moon should be fairly plain. Look for the penumbral shadow to move from (celestial) east to west across the disc. You might be able to detect lesser traces of penumbral shading for about 45 minutes before and after mid-eclipse.
The image below shows the penumbral lunar eclipse of November 28, 2012. From Quezon City in the Phillipines, Raven Yu used identical camera settings to shot the lunar disk at mid-eclipse and afterward the event ended. Note the changes in appearance of the lunar disk, which here is shown north up. During the eclipse on October 18, 2013, penumbral shading should be most noticeable on the Moon's southern half.
Unusual shading on the southern half of the Moon should be fairly plain. Look for the penumbral shadow to move from (celestial) east to west across the disc. You might be able to detect lesser traces of penumbral shading for about 45 minutes before and after mid-eclipse.
The image below shows the penumbral lunar eclipse of November 28, 2012. From Quezon City in the Phillipines, Raven Yu used identical camera settings to shot the lunar disk at mid-eclipse and afterward the event ended. Note the changes in appearance of the lunar disk, which here is shown north up. During the eclipse on October 18, 2013, penumbral shading should be most noticeable on the Moon's southern half.
As the map below shows, the event will also be visible in evening from the Caribbean and South America. In Europe and Africa, it happens in the middle of the night with the Moon high in the sky. For observers in western, central, and southern Asia, it happens before or during dawn on the 19th.
The penumbral lunar eclipse on October 18, 2013, favors observers in Europe, Africa, and western Asia.
F. Espenak / NASA-GSFC
Observer's Image Gallery From Friday Night's Events (October 12, 2013)
Below are a few images sent in by observers of a number of yesterday's sky events. At left, an image Taken by Oscar Martín Mesonero in Salamanca, Spain of the triple shadow transit of three of Jupiter's Galilean moons. At center are spectacular sets of different types of overlapping auroral curtains captured by C.K. Man near Yellowknife, NWT, Canada. At the right is an image of comet ISON near Mars early in the morning sky (Photo by Norbert Mrozek).
Jovian Triple Shadow Transit and Demon Star Drop Tonight (October 11, 2013)
Observers heading out tonight at sunset will be greeted by a bright orb in the southern sky as the moon reaches its first-quarter phase near sunset (exactly at 7:02 p.m. Eastern Daylight Time). In this "half lit" state, it shines above the tilting Sagittarius Teapot in early evening.
A more spectacular event happens later in the evening: A triple shadow transit on Jupiter. A rare case of three moons — Io, Europa, and Callisto — casting their tiny black shadows onto Jupiter at once happens late tonight, from 4:32 to 5:37 Universal Time October 12th (12:32 to 1:37 a.m. Saturday morning Eastern Daylight Time). Jupiter will be high and best placed for telescope users in Europe and Africa, and low in the eastern sky for eastern North America.
Meanwhile, observers may want to have a look tonight at the famous "demon star" in the constellation Perseus. Algol, also known as Beta Persei , is the prototype of eclipsing binary stars. It should be in one of its periodic dimmings tonight - magnitude 3.4 instead of its usual 2.1 - for a couple hours centered on 8:53 p.m. EDT. Algol takes several additional hours to fade and to rebrighten. Here's a comparison-star chart giving the magnitudes of three stars near Algol. Use them to judge its changing brightness.
A more spectacular event happens later in the evening: A triple shadow transit on Jupiter. A rare case of three moons — Io, Europa, and Callisto — casting their tiny black shadows onto Jupiter at once happens late tonight, from 4:32 to 5:37 Universal Time October 12th (12:32 to 1:37 a.m. Saturday morning Eastern Daylight Time). Jupiter will be high and best placed for telescope users in Europe and Africa, and low in the eastern sky for eastern North America.
Meanwhile, observers may want to have a look tonight at the famous "demon star" in the constellation Perseus. Algol, also known as Beta Persei , is the prototype of eclipsing binary stars. It should be in one of its periodic dimmings tonight - magnitude 3.4 instead of its usual 2.1 - for a couple hours centered on 8:53 p.m. EDT. Algol takes several additional hours to fade and to rebrighten. Here's a comparison-star chart giving the magnitudes of three stars near Algol. Use them to judge its changing brightness.
© Jens Dengler (Artwork from John Goodricke
in The Sky over Berlin, used with permission)
Star A is separated from close companion B
by less than a tenth (0.062) of the Earth-Sun
distance (AU). Dimmer Star B partially eclipses
Star A every 2.9 days and loses gas in a "star
stream" that impacts Star A before bouncing
back out to create a "transient accretion
annulus" around Star A
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Algol (centre) and Rho Persei (redish comparison star below it) when Algol is at its normal brilliance and eclipsed.
Photos taken by the author August 10 and 11, 2007. Images by Larry McNish.
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Comet ISON Starting to Brighten
(October 11, 2013)
As comet ISON moves inward this week from the orbital distance of Mars, it is beginning to brighten more rapidly and noticeable changes in its appearance are becoming more easily observed. At the moment it is glowing like a 10th magnitude star, too dim for naked-eye viewing but an easy target for many telescopes on Earth. "This is what the comet looked like on Oct. 8th using the 0.8m (32 inch) Schulman Telescope," reports Adam Block from the University of Arizona Skycenter atop Mount Lemmon:
ISON's green color comes from the gases surrounding its icy nucleus. Jets spewing from the comet's core contain diatomic carbon (C2) and cyanogen (CN: a poisonous gas found in many comets). Both substances glow green when illuminated by sunlight in the near-vacuum of space.
"I am certain more images of Comet ISON will be coming out shortly as it increases in brightness during its dive towards the Sun," adds Block. "Here is hoping it survives that rendezvous on Nov. 28th and emerges as something spectacular on the other side!"
Although the comet is very faint, finding it is easy. Comet ISON rises alongside Mars in the eastern sky just before dawn. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Special dates of interest include Oct. 13-15 when Mars, Comet ISON, and the first magnitude star Regulus will be clustered in a patch of sky less than 3o apart. Red Mars and blue Regulus will form a beautiful naked eye "double star" in the early morning sky. Sky maps: Oct. 10, 11, 12, 13, 14,15.
"I am certain more images of Comet ISON will be coming out shortly as it increases in brightness during its dive towards the Sun," adds Block. "Here is hoping it survives that rendezvous on Nov. 28th and emerges as something spectacular on the other side!"
Although the comet is very faint, finding it is easy. Comet ISON rises alongside Mars in the eastern sky just before dawn. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Special dates of interest include Oct. 13-15 when Mars, Comet ISON, and the first magnitude star Regulus will be clustered in a patch of sky less than 3o apart. Red Mars and blue Regulus will form a beautiful naked eye "double star" in the early morning sky. Sky maps: Oct. 10, 11, 12, 13, 14,15.
Sundiving Comet A Cousin of ISON?
(October 10,2013)
Comet ISON is not the only comet diving toward the sun. Another smaller comet is feeling the heat today. Using a coronagraph to block the sun's glare, the Solar and Heliospheric Observatory (SOHO) is monitoring the comet's death plunge:
This comet is a member of the Kreutz family. Seen falling into the sun dozens of times each year, Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail.
Today's sungrazer is probably doomed. The vast majority of Kreutz comets are small (no more than ~10 m wide) and they evaporate completely as they approach the sun. Comet ISON, on the other hand, is large (~0.5 km wide) and widely expected to survive its brush with the sun on Nov. 28th. It's a tale of two comets!
Update: Yesterday, the sungrazer comet made its close approach to the sun but did not come out again. The icy visitor from the outer solar system was blasted by solar heat and completely destroyed. SOHO recorded the doomed comet's last moments:
Today's sungrazer is probably doomed. The vast majority of Kreutz comets are small (no more than ~10 m wide) and they evaporate completely as they approach the sun. Comet ISON, on the other hand, is large (~0.5 km wide) and widely expected to survive its brush with the sun on Nov. 28th. It's a tale of two comets!
Update: Yesterday, the sungrazer comet made its close approach to the sun but did not come out again. The icy visitor from the outer solar system was blasted by solar heat and completely destroyed. SOHO recorded the doomed comet's last moments:
Rare Triple Shadow Transit of Galilean Moons Across Jupiter's Disk on Friday
(October 8, 2013) by Bob King, UniverseToday.com
Jupiter with polka dot shadows cast by Io, Europa and Callisto as depicted around 1 a.m. EDT Oct. 12. Watch for the Great Red Spot to come into view during the transit. Created with Claude Duplessis’ Meridian software
Talk about a great fall lineup. Three of Jupiter’s four brightest moons plan a rare show for telescopic observers on Friday night – Saturday morning Oct. 11-12. For a span of just over an hour, Io, Europa and Callisto will simultaneously cast shadows on the planet’s cloud tops, an event that hasn’t happened since March 28, 2004.
Who doesn’t remember their first time looking at Jupiter and his entourage of dancing moons in a telescope? Because each moves at a different rate depending on its distance from the planet, they’re constantly on the move like kids in a game of musical chairs. Every night offers a different arrangement.
Some nights all four of the brightest are strung out on one side of the planet, other nights only two or three are visible, the others hidden behind Jupiter’s “plus-sized” globe. Occasionally you’ll be lucky enough to catch the shadow of one of moons as it transits or crosses in front of the planet. We call the event a shadow transit, but to someone watching from Jupiter, the moon glides in front of the sun to create a total solar eclipse.
Since the sun is only 1/5 as large from Jupiter as seen from Earth, all four moons are large enough to completely cover the sun and cast inky shadows. To the eye they look like tiny black dots of varying sizes. Europa, the smallest, mimics a pinprick. The shadows of Io and Callisto are more substantial. Ganymede, the solar system’s largest moon at 3,269 miles (5,262 km), looks positively plump compared to the others. Even a small telescope magnifying around 50x will show it.
Who doesn’t remember their first time looking at Jupiter and his entourage of dancing moons in a telescope? Because each moves at a different rate depending on its distance from the planet, they’re constantly on the move like kids in a game of musical chairs. Every night offers a different arrangement.
Some nights all four of the brightest are strung out on one side of the planet, other nights only two or three are visible, the others hidden behind Jupiter’s “plus-sized” globe. Occasionally you’ll be lucky enough to catch the shadow of one of moons as it transits or crosses in front of the planet. We call the event a shadow transit, but to someone watching from Jupiter, the moon glides in front of the sun to create a total solar eclipse.
Since the sun is only 1/5 as large from Jupiter as seen from Earth, all four moons are large enough to completely cover the sun and cast inky shadows. To the eye they look like tiny black dots of varying sizes. Europa, the smallest, mimics a pinprick. The shadows of Io and Callisto are more substantial. Ganymede, the solar system’s largest moon at 3,269 miles (5,262 km), looks positively plump compared to the others. Even a small telescope magnifying around 50x will show it.
Jupiter on Sept. 24 with its moon Europa (at left) casting a pinhead black shadow on Jupiter’s clouds. Credit: John Chumack
The three inner satellites – Io, Europa and Ganymede – have shadow transits every orbit. Distant Callisto only transits when Jupiter’s tilt relative to Earth is very small, i.e. the plane of the planet’s moons is nearly edge-on from our perspective. Callisto transits occur in alternating “seasons” lasting about 3 years apiece. Three years of shadow play are followed by three years of shadowless misses. Single transits are fairly common; you can find tables of them online like this one from Project Pluto or plug in time and date into a free program like Meridian for a picture and list of times.
Because Io, Europa and Ganymede orbit in a 4:2:1 resonance (Io revolves four times around Jupiter in the time it takes Ganymede to orbit once; Europa completes two orbits for Ganymede’s one) it’s impossible for all three to line up – along with Callsto – for a “quadruple transit”. Credit: Matma Rex / Wikipedia
Seeing two shadows inch across Jupiter’s face is very uncommon, and three are as rare as a good hair day for Donald Trump. Averaged out, triple transits occur once or twice a decade. Friday night Oct. 11 each moon enters like actors in a play. Callisto appears first at 11:12 p.m. EDT followed by Europa and then Io. By 12:32 a.m. all three are in place.
Catch them while you can. Groups like these don’t last long. A little more than an hour later Callisto departs, leaving just two shadows. You’ll find the details below. All times are Eastern Daylight or EDT. Subtract one hour for Central time and add four hours for BST (British Summer Time):
* Callisto’s shadow enters the disk – 11:12 p.m. Oct. 11
* Europa – 11:24 p.m.
* Io – 12:32 a.m.
** TRIPLE TRANSIT from 12:32 – 1:37 a.m.
* Callisto departs – 1:37 a.m.
* Europa departs – 2:01 a.m.
* Io departs – 2:44 a.m.
Catch them while you can. Groups like these don’t last long. A little more than an hour later Callisto departs, leaving just two shadows. You’ll find the details below. All times are Eastern Daylight or EDT. Subtract one hour for Central time and add four hours for BST (British Summer Time):
* Callisto’s shadow enters the disk – 11:12 p.m. Oct. 11
* Europa – 11:24 p.m.
* Io – 12:32 a.m.
** TRIPLE TRANSIT from 12:32 – 1:37 a.m.
* Callisto departs – 1:37 a.m.
* Europa departs – 2:01 a.m.
* Io departs – 2:44 a.m.
Looking at Jupiter from high above the plane of the solar system in this diagram from more than a century ago, we can better picture how shadow transits and eclipses happen. The tiny disk of Io and the shadow of Ganymede are seen in transit; Callisto is about to be eclipsed by Jupiter’s shadow. Credit: Garrett Serviss from “Pleasures of the Telescope” (annotations: Bob King)
The triple transit will be seen across the eastern half of the U.S., Europe, Africa and Western Asia. Those living on the East Coast have the best view in the U.S. with Jupiter some 20-25 degrees high in the northeastern sky around 1 a.m. local time. Things get dicier in the Midwest where Jupiter climbs to only 5-10 degrees. From the mountain states the planet won’t rise until Callisto’s shadow has left the disk, leaving a two-shadow consolation prize. If you live in the Pacific time zone and points farther west, you’ll unfortunately miss the event altogether.
Draconid Meteor Shower, Jupiter at Quadrature and Venus Meets the Moon
(October 7, 2013)
During twilight tonight, the waxing crescent Moon shines to the right of Venus. Well to the Moon's lower right, while twilight is still fairly bright, binoculars show Saturn above Mercury. Be sure to find a location to observe from with a low horizon - such as the east side of a baseball diamond or park - so that you don't miss out on seeing Saturn and Mercury down low. Be ready to observe within a half hour after sunset. On Wednesday night, look just 3/4 of a degree above Venus and you'll see the surprising variable star Delta Scorpii, which brightened suddenly a few years ago and still is undergoing small changes in brightness at irregular intervals.
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This week, Jupiter reaches western quadrature - that's where it forms a 90 deg. angle in the sky with the earth and the sun. In a telescope, the western edge of Jupiter is most clearly dimmer than its eastern, more sunward-facing edge.
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Image by Sean Walker
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The Draconid meteor shower will sweep across U.S. skies early Monday evening just after sunset.
Although not among the showiest showers of the year, the Draconids stand out for one reason: Unlike most meteor showers, they are best seen in the evening rather than before dawn. That makes them a great introduction to sky-watching because they don't require getting up early.
The shower this year should also be good watching because the moon is waxing and won't reflect enough light to significantly interfere with the display.
Some Draconids should also be visible just after sunset Tuesday evening, but that display is not expected to be as large.
Last year's Draconid shower was especially lively, which means this year the meteors are likely to be a little more sedate, according to EarthSky, a science news blog.
The name comes from the way the meteors appear to emanate from the northern constellation Draco the Dragon, which sits just above the Little Dipper in the night sky.
The meteors are the result of tiny bits of dust and ice debris left behind by the Giacobini-Zinner comet, which circles the sun every 6.6 years. As the Earth passes through this trail of cosmic debris, the particles burn up in our atmosphere, creating the fiery trails we call falling stars.
The Draconids are notoriously unpredictable. Some years they are impressive, with thousands of falling stars per hour, and other years they are much more sedate. Showers in 1933 and 1946 were especially large.
To get the best view, find an area away from city lights so the eyes can adjust to the darkness for at least 20 minutes. Astronomers suggest lying on a blanket or reclining chair to get a full-sky view.
Although not among the showiest showers of the year, the Draconids stand out for one reason: Unlike most meteor showers, they are best seen in the evening rather than before dawn. That makes them a great introduction to sky-watching because they don't require getting up early.
The shower this year should also be good watching because the moon is waxing and won't reflect enough light to significantly interfere with the display.
Some Draconids should also be visible just after sunset Tuesday evening, but that display is not expected to be as large.
Last year's Draconid shower was especially lively, which means this year the meteors are likely to be a little more sedate, according to EarthSky, a science news blog.
The name comes from the way the meteors appear to emanate from the northern constellation Draco the Dragon, which sits just above the Little Dipper in the night sky.
The meteors are the result of tiny bits of dust and ice debris left behind by the Giacobini-Zinner comet, which circles the sun every 6.6 years. As the Earth passes through this trail of cosmic debris, the particles burn up in our atmosphere, creating the fiery trails we call falling stars.
The Draconids are notoriously unpredictable. Some years they are impressive, with thousands of falling stars per hour, and other years they are much more sedate. Showers in 1933 and 1946 were especially large.
To get the best view, find an area away from city lights so the eyes can adjust to the darkness for at least 20 minutes. Astronomers suggest lying on a blanket or reclining chair to get a full-sky view.
Neighbouring Star With Exoplanet May Be a Triplet! (October 4, 2013)
by Elizabeth Howell, UniverseToday.com
This false-color composite image, taken with the Hubble Space Telescope, reveals the orbital motion of the planet Fomalhaut b. Credit: NASA, ESA, and P. Kalas (University of California, Berkeley and SETI Institute)
Fomalhaut is a really cool place to study. The naked-eye star (the brightest star in the constellation Piscis Austrinus) has a planet, Fomalhaut b, that once appeared dead but rose again in science circles. It is the site of a comet massacre. Now it’s getting even more interesting: Scientists have believed for years that Fomalhaut is a double star, but a new paper proposes that it is actually a triplet.
Fomalhaut is one of the brightest stars in the southern part of the sky - seen here low in the southeast at about 9:30 PM these nights.
“I noticed this third star a couple of years ago when I was plotting the motions of stars in the vicinity of Fomalhaut for another study,” stated Eric Mamajek, associate professor of physics and astronomy at the University of Rochester. The third star is known as LP876-10 or Fomalhaut C.
“However, I needed to collect more data and gather a team of co-authors with different observations to test whether the star’s properties are consistent with being a third member of the Fomalhaut system.”
That opportunity came when Mamajek was in Chile and by chance, talking with Georgia State University’s Todd Henry, who is the director of the Research Consortium on Nearby Stars. A student (who has now graduated), Jennifer Bartlett at the University of Virginia, was working on a study of potential nearby stars for her Ph.D. thesis, which included the star that Mamajek was curious about.
“However, I needed to collect more data and gather a team of co-authors with different observations to test whether the star’s properties are consistent with being a third member of the Fomalhaut system.”
That opportunity came when Mamajek was in Chile and by chance, talking with Georgia State University’s Todd Henry, who is the director of the Research Consortium on Nearby Stars. A student (who has now graduated), Jennifer Bartlett at the University of Virginia, was working on a study of potential nearby stars for her Ph.D. thesis, which included the star that Mamajek was curious about.
Herschel’s far-infrared observations of Fomalhaut and its disk. Credit: ESA
The team plotted the star’s movements and spectroscopy (to see its temperature and radial velocity) and concluded the speed and distance of the star matched that of the Fomalhaut system.
LP876-10/Fomalhaut C is a red dwarf that appears the distance of 11 full moons apart from Fomalhaut in the night sky. It seems counterintuitive to believe they are close together, but the team reminds us that Fomalhaut is very close to us as stars go: 25 light-years away.
“That they appear so far apart could explain why the connection between LP 876-10 and Fomalhaut had been previously missed,” the team stated.
LP876-10/Fomalhaut C is a red dwarf that appears the distance of 11 full moons apart from Fomalhaut in the night sky. It seems counterintuitive to believe they are close together, but the team reminds us that Fomalhaut is very close to us as stars go: 25 light-years away.
“That they appear so far apart could explain why the connection between LP 876-10 and Fomalhaut had been previously missed,” the team stated.
Uranus's Hitch-hiking Companions(October 3, 2013)
by Kelly Beatty, skyandtelescope.com
Our solar system's major planets can be variously grouped into "haves" and "have nots." For example, none of the inner planets have rings, though all the outer ones do. Innermost Venus and Mercury are the only two that lack moons, likely having lost them to the Sun's gravitational grip. Mars and Venus lack magnetic fields, and so on.
One of the odder discriminants involves Trojans, small bodies that share a planet's "personal space" by maintaining a location 60° ahead of or behind it in the same orbit. These locations, known as the L4 and L5Lagrange points, are gravitationally stable niches where small bodies can congregate.
One of the odder discriminants involves Trojans, small bodies that share a planet's "personal space" by maintaining a location 60° ahead of or behind it in the same orbit. These locations, known as the L4 and L5Lagrange points, are gravitationally stable niches where small bodies can congregate.
One of three discovery images of the object 2011 QF99 (inside green circle) taken 1 hour apart on October 24, 2011, with the Canada-France-Hawaii Telescope. Click on the image for a larger view.
M. Alexandersen & others
Jupiter has a vast retinue of Trojan companions, 5,887 of them at last count. By some estimates, its two big Trojan clouds are more populous than the main asteroid belt. Neptune has nine, though in theory it should have 10 times more large Trojans than Jupiter does. Earth has one (the object 2010 TK7, discovered in 2010), along with a handful of unstable "quasi-satellites". Mars has eight Trojans.
By contrast, dynamicists believe that the trapping regions of Saturn and Uranus aren't stable. Yet a team led by Mike Alexandersen (University of British Columbia) has discovered a body, designated 2011 QF99, preceding Uranus near the L4 point.
The observers were conducting a deep, wide-field survey for trans-Neptunian objects with the 3.6-meter Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. Initially they thought they'd chanced upon something drifting randomly among the outer planets, one of many such mavericks known as Centaurs. However, as detailed in the August 30th issue of Science, its motion over 14 months showed that 2011 QF99 was more than that.
By contrast, dynamicists believe that the trapping regions of Saturn and Uranus aren't stable. Yet a team led by Mike Alexandersen (University of British Columbia) has discovered a body, designated 2011 QF99, preceding Uranus near the L4 point.
The observers were conducting a deep, wide-field survey for trans-Neptunian objects with the 3.6-meter Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. Initially they thought they'd chanced upon something drifting randomly among the outer planets, one of many such mavericks known as Centaurs. However, as detailed in the August 30th issue of Science, its motion over 14 months showed that 2011 QF99 was more than that.
A simulation shows the orbital motion of 2011 QF99, relative to Uranus, over the next 59,000 years. L4 and L5 are gravitationally stable Lagrange points.
M. Alexandersen & others / Science
Computer simulations suggest that the object, estimated to be 40 miles (60 km) across, is keeping Uranus company only temporarily. The planet likely captured 2011 QF99 within the astronomically recent past, perhaps less than 100,000 years ago, and the object will gradually spiral its way out of the planet's gravitational grip within the next million years or so. Here's a video showing how its orbit evolves over time.
Their interest piqued, Alexandersen and his team then explored how often these temporary coorbital couplings occur. Their modeling led to a surprising result: far more bodies within 34 astronomical units of the Sun should be lingering as Trojans of Uranus and Neptune than anyone had imaged. At any given time, about 1% of them are temporarily bound to Uranus and another 2% to Neptune.
"This tells us something about the current evolution of the solar system," Alexandersen notes in a UBC press release. These come-and-go captives offer a window on how the giant planets interacted with a vast population of small bodies in the early solar system and migrated to their present locations.
Their interest piqued, Alexandersen and his team then explored how often these temporary coorbital couplings occur. Their modeling led to a surprising result: far more bodies within 34 astronomical units of the Sun should be lingering as Trojans of Uranus and Neptune than anyone had imaged. At any given time, about 1% of them are temporarily bound to Uranus and another 2% to Neptune.
"This tells us something about the current evolution of the solar system," Alexandersen notes in a UBC press release. These come-and-go captives offer a window on how the giant planets interacted with a vast population of small bodies in the early solar system and migrated to their present locations.
Uranus Arrives At Its Yearly Best
(October 2, 2013)
The current location of Uranus in Pisces. Created by the author using Stellarium.
Up for a challenge? Got a big 12” light bucket of a Dobsonian telescope and looking for something new to point it at? This week, as the Moon reaches New phase on October 4th and stays safely out of the late evening sky, why not check out Uranus and its retinue of moons. And yes, we’ve heard just about ALL the Uranus jokes —its pronounced yer-in-us, thank you very much — but feel free to attempt to pen an original if you must.
Now, back to astronomy. Uranus reaches opposition for 2013 on Thursday, October 3rd at 14:00 Universal Time. Opposition is the point in time that an outer planet rises as the Sun sets. In the case of Uranus, its opposition dates advance forward by about 4-5 days each year.
Now, back to astronomy. Uranus reaches opposition for 2013 on Thursday, October 3rd at 14:00 Universal Time. Opposition is the point in time that an outer planet rises as the Sun sets. In the case of Uranus, its opposition dates advance forward by about 4-5 days each year.
This also marks the start of the best time to hunt for the planet among the star fields of the constellation Pisces. Uranus will reach its maximum elevation above the southern horizon for northern hemisphere viewers for early October around local midnight. For observers south of the equator, Uranus will transit to the north. Incidentally, Uranus also currently sits near the equinoctial point occupied by the Sun during the March equinox, making viewing opportunities nearly equal for both hemispheres.
Uranus is 19.04 astronomical units distant during opposition 2013, or about 158 light minutes away. Shining at magnitude +5.8, Uranus presents a tiny blue-green disk just under 4” across at opposition.
Uranus currently lies six degrees SW of the +4.4 magnitude star Delta Piscium, on the border of the constellations Pisces and Cetus. Uranus will actually be crossing once again into the non-zodiacal constellation of Cetus later this year.
Discovered in 1781 by Sir William Herschel, Uranus has only completed 2 full orbits (2.75 to be precise) in its 84.3 year trips about the Sun. We can be thankful that William’s proposal to name the planet Geogium Sidus after his benefactor King George the III didn’t stick!
Uranus is 19.04 astronomical units distant during opposition 2013, or about 158 light minutes away. Shining at magnitude +5.8, Uranus presents a tiny blue-green disk just under 4” across at opposition.
Uranus currently lies six degrees SW of the +4.4 magnitude star Delta Piscium, on the border of the constellations Pisces and Cetus. Uranus will actually be crossing once again into the non-zodiacal constellation of Cetus later this year.
Discovered in 1781 by Sir William Herschel, Uranus has only completed 2 full orbits (2.75 to be precise) in its 84.3 year trips about the Sun. We can be thankful that William’s proposal to name the planet Geogium Sidus after his benefactor King George the III didn’t stick!
Five of the 27 known moons of Uranus are also within the grasp of a moderate-sized backyard scope as well. The trick is to catch ‘em near greatest elongation, when they appear farthest from the “glare of Uranus” (hey, there’s a freebie for a snicker or two). An eyepiece equipped with an occulting bar, or simply nudging Uranus out of the field of view can also help.
With magnitudes ranging from +13 to +16, the moons of Uranus are similar in brightness to Neptune’s large moon Triton or the tiny world Pluto.
The five brightest moons of Uranus and their respective maximum elongations are:
With magnitudes ranging from +13 to +16, the moons of Uranus are similar in brightness to Neptune’s large moon Triton or the tiny world Pluto.
The five brightest moons of Uranus and their respective maximum elongations are:
The first two moons were named Titania and Oberon by William’s son John after characters from William Shakespeare’s A Mid-Summer Night’s Dream. William discovered the first two moons of Uranus on the night of January 11th, 1787 using his 49.5” reflector. His scopes were so advanced for his day, that it wasn’t until over a half a century later that William Lassell discovered Umbriel and Ariel using the Liverpool Observatory’s 24” reflector in 1851.
Gerard Kuiper would later add tiny Miranda to the list, nabbing it with the McDonald Observatory’s 82” Otto Struve Telescope in 1948. We would then have to wait until Voyager 2’s 1986 flyby of Uranus in 1986 to add more. To date, Voyager 2 remains the only spacecraft to visit Uranus and Neptune.
The current convention established by the International Astronomical Union is to name the moons of Uranus after characters from the plays of Shakespeare or Alexander Pope’s Rape of the Lock.
There’s still a wide range of names in said literature to choose from!
It’s interesting to note that the orbits of the moons of Uranus are also currently tipped open about 25 degrees to our line of sight and widening. They were edge on in December 2007, and will be perpendicular to our Earthly view come 2029, after which they’ll head back to edge on in 2049. This is because Uranus and the orbits of its moons are tipped at a 97 degree angle relative to the planet’s orbit. This is why elongations for its moons are often quoted it terms of “north and south” of the planet, rather than the familiar east and west. Shadow transits of the moons can occur with about a year and a half during plane-crossing seasons, but they’re ~42 years apart and tough to spot on the tiny disk of Uranus!
Gerard Kuiper would later add tiny Miranda to the list, nabbing it with the McDonald Observatory’s 82” Otto Struve Telescope in 1948. We would then have to wait until Voyager 2’s 1986 flyby of Uranus in 1986 to add more. To date, Voyager 2 remains the only spacecraft to visit Uranus and Neptune.
The current convention established by the International Astronomical Union is to name the moons of Uranus after characters from the plays of Shakespeare or Alexander Pope’s Rape of the Lock.
There’s still a wide range of names in said literature to choose from!
It’s interesting to note that the orbits of the moons of Uranus are also currently tipped open about 25 degrees to our line of sight and widening. They were edge on in December 2007, and will be perpendicular to our Earthly view come 2029, after which they’ll head back to edge on in 2049. This is because Uranus and the orbits of its moons are tipped at a 97 degree angle relative to the planet’s orbit. This is why elongations for its moons are often quoted it terms of “north and south” of the planet, rather than the familiar east and west. Shadow transits of the moons can occur with about a year and a half during plane-crossing seasons, but they’re ~42 years apart and tough to spot on the tiny disk of Uranus!
Line up a ruler or straight edge horizontally with the date on the left hand side of the image to determine the exact orientation of the moons with Uranus' disk (which is the dark band running vertically down the centre of the image).
Uranus also reached aphelion in 2009 at 20.099 AU from the Sun —we’re still at the farther end of the spectrum, as oppositions of Uranus can range from 19.09 to 17.28 AU distant.
Uranus will rise earlier on each successive evening until it reaches quadrature at the end of the year on December 30th. At this point, it’ll be roughly due south at local sunset. Keep in mind, there’s also another ice giant worth hunting for in the adjacent constellation of Aquarius named Neptune.
So ignore those bad puns, and be sure to take out that 8” (scope, that is) and point it at Uranus!
Uranus will rise earlier on each successive evening until it reaches quadrature at the end of the year on December 30th. At this point, it’ll be roughly due south at local sunset. Keep in mind, there’s also another ice giant worth hunting for in the adjacent constellation of Aquarius named Neptune.
So ignore those bad puns, and be sure to take out that 8” (scope, that is) and point it at Uranus!
Comet ISON Makes Close Approach to Mars (October 1, 2013)
In two months, Comet ISON will make a spectacular flyby of the sun. First, though, it has to fly by Mars. Today, the comet is passing by the Red Planet only 0.07 AU (10.5 million km) away. This is giving Mars satellites and rovers our first close-up view of the sungrazer.
Amateur astronomers on Earth are watching the close encounter from afar. This photo from Malcolm Park of Oak Heights, Ontario, shows the location of the comet relative to Mars just before sunrise on Sept. 29th:
Amateur astronomers on Earth are watching the close encounter from afar. This photo from Malcolm Park of Oak Heights, Ontario, shows the location of the comet relative to Mars just before sunrise on Sept. 29th:
At closest approach, Mars and Comet ISON will be approximately 2 deg. apart. While Mars is visible to the unaided eye (it shines almost as brightly as a first-magnitude star), ISON is not. The comet is still far from the sun and, as it crosses the orbit of Mars, it has not yet warmed enough to reach naked-eye visibility. Reports of the comet's brightness vary from 12th to 14th magnitude, which means a mid-sized backyard telescope is required to see it.
Mars and ISON rise together in the eastern sky a couple of hours before the sun. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Visually, Mars will be easy to find on the mornings of closest approach, not only because the planet is relatively bright, but also because the crescent Moon will be passing right by it. Sky maps: Oct. 1, 2.
Mars and ISON rise together in the eastern sky a couple of hours before the sun. Amateur astronomers, if you have a GOTO telescope, enter these coordinates. Visually, Mars will be easy to find on the mornings of closest approach, not only because the planet is relatively bright, but also because the crescent Moon will be passing right by it. Sky maps: Oct. 1, 2.
Comet ISON Goes Green as It Passes Mars (October 1, 2013)
by BOB KING
Comet ISON, photographed with a 3-inch (80mm) telescope this morning Sept. 28 shows a circular green coma and head. A short dust tail points to the northwest. Credit: Michael Jaeger
As NASA and the European Space Agency prepare their remote photo-journalists – Mars Express, Mars Reconnaissance Orbiter and the Curiosity and Opportunity rovers – to capture photos of Comet ISON’s flyby of Mars over the next few days, amateur astronomers continue to monitor and photograph the comet from backyard observatories across the blue Earth. Several recent color photos show ISON’s bright head or nucleus at the center of a puffy, green coma. Green’s a good omen – a sign the comet’s getting more active as it enters the realm of the inner solar system and sun’s embrace.
Another great photo of the “greening” of Comet ISON taken on Sept. 24 with a 17-inch (43-cm) telescope. Click to enlarge. Credit: Damian Peach
Sunlight beating down on the comet’s nucleus (core) vaporizes dust-impregnated ice to form a cloud or coma, a temporary atmosphere of water vapor, dust, carbon dioxide, ammonia and other gases. Once liberated , the tenuous haze of comet stuff rapidly expands into a huge spherical cloud centered on the nucleus. Comas are typically hundreds of thousands of miles across but are so rarified you could wave your hand through one and not feel a thing. The Great Comet of 1811 sported one some 864,000 miles (1.4 million km) across, nearly the same diameter as the sun!
Among the materials released by solar heating re cyanogen and diatomic carbon. Both are colorless gases that fluoresce a delicious candy-apple green when excited by energetic ultraviolet light in sunlight.
Among the materials released by solar heating re cyanogen and diatomic carbon. Both are colorless gases that fluoresce a delicious candy-apple green when excited by energetic ultraviolet light in sunlight.
Sounds like a plan. Newspaper clipping from 1910.
Cyanogen smells pleasantly of almonds, but it’s a poisonous gas composed of one atom each of carbon and nitrogen. Diatomic carbon or C2 is equally unpleasant. It’s a strong, corrosive acid found not only in comets but also created as a vapor in high-energy electric arcs. But nature has a way of taking the most unlikely things and fashioning them into something beautiful. If you’re concerned about the effects of cometary gas and dust on people, rest easy. They’re spread too thinly to touch us here on Earth. That didn’t stop swindlers from selling “comet pills” and gas masks to protect the public from poisoning during the 1910 return of Halley’s Comet. Earth passed through the tail for six hours on May 19 that year. Amazingly, those who took the pills survived … as did everyone else.
Comet ISON’s location and approximate appearance on October 1 seen from the Curiosity Rover. ISON will pass only 6.7 million miles (10.8 million km) from Mars on Tuesday Oct. 1. Stellarium
While Comet ISON is still too faint for visual observers to discern its Caribbean glow, that will change as it beelines for the sun and brightens. If you could somehow wish yourself to Mars in the next few days, I suspect you’d easily see the green coma through a telescope. The comet – a naked eye object at magnitude 2.5-3 – glows low in the northern sky from the Curiosity rover’s vantage point 4.5 degrees south of the Martian equator.
Today the comet makes a close fly-by of Mars on its inbound journey, passing just 10 million km from the planet. A pretty spectacular sight to be sure - if you could observe it from Mars' surface! For now, we'll have to wait a few more weeks until the comet grows large and bright enough for our own chance to see this amazing visitor without optical aid!
Today the comet makes a close fly-by of Mars on its inbound journey, passing just 10 million km from the planet. A pretty spectacular sight to be sure - if you could observe it from Mars' surface! For now, we'll have to wait a few more weeks until the comet grows large and bright enough for our own chance to see this amazing visitor without optical aid!
Comet ISON Now Within Range of Moderate-Size Scopes (September 19, 2013)
Still more than two months away from its spectacular close encounter with the Sun on November 23rd, comet ISON hasn't yet developed into the bright beautiful dagger in the sky that some are expecting it to become. However, an increasing number of amateur astronomers are just too excited to wait for the comet's transformation. The brightening comet has become a good target for backyard telescopes in the pre-dawn sky and pictures of the comet are pouring in. Last night, advanced amateur astronomer Chris Schur captured this image from his home observatory in Payson, Arizona:
This 25 minute exposure shows the comet through a 12 inch telescope," says Schur. "The image has sharp focus, perfect tracking and the star trails are unbroken and smooth. A nearby star added to the nice composition."
At the moment, ISON is too dim for the naked eye--"I estimate the comet's magnitude to be +12.5," says Schur--but it is on track to become an impressive sungrazer. For comparison, Comet ISON is brighter than Comet Lovejoy was in 2011 at a similar distance from the sun. The fact that Comet Lovejoy turned into aspectacular sungrazer bodes well for the performance of Comet ISON.
Observers of Comet ISON will notice that it is in the same part of the sky as Mars. The comet will make a close approach to the Red Planet on October 1st, and during that time Mars satellites will be taking ISON's picture at point blank range. Those images will likely rival or improve upon the view from Earth.
The comet this week is located just to the east-northeast of the Beehive cluster in the the constellation Cancer the Crab, visible in the eastern sky in the hours before sunrise. For detailed finder charts visit here or here.
At the moment, ISON is too dim for the naked eye--"I estimate the comet's magnitude to be +12.5," says Schur--but it is on track to become an impressive sungrazer. For comparison, Comet ISON is brighter than Comet Lovejoy was in 2011 at a similar distance from the sun. The fact that Comet Lovejoy turned into aspectacular sungrazer bodes well for the performance of Comet ISON.
Observers of Comet ISON will notice that it is in the same part of the sky as Mars. The comet will make a close approach to the Red Planet on October 1st, and during that time Mars satellites will be taking ISON's picture at point blank range. Those images will likely rival or improve upon the view from Earth.
The comet this week is located just to the east-northeast of the Beehive cluster in the the constellation Cancer the Crab, visible in the eastern sky in the hours before sunrise. For detailed finder charts visit here or here.
Comet ISON finder chart for September and October. Click to enlarge.