Enormous Ring of Debris Around Young Star Holds Clues to Planet Formation
(March 9, 2018) NEWS RELEASE FROM HUBBLESITE.ORG
Astronomers have used NASA’s Hubble Space Telescope to uncover a vast, complex dust structure, about 150 billion miles across, enveloping the young star HR 4796A. A bright, narrow, inner ring of dust is already known to encircle the star and may have been corralled by the gravitational pull of an unseen giant planet. This newly discovered huge structure around the system may have implications for what this yet-unseen planetary system looks like around the 8-million-year-old star, which is in its formative years of planet construction.
To spot Mercury this coming week, look for a bright "star" along the horizon after sunset, well to the lower left of Altair.
Sky & Telescope diagram
The debris field of very fine dust was likely created from collisions among developing infant planets near the star, evidenced by a bright ring of dusty debris seen 7 billion miles from the star. The pressure of starlight from the star, which is 23 times more luminous than the Sun, then expelled the dust far into space.
But the dynamics don’t stop there. The puffy outer dust structure is like a donut-shaped inner tube that got hit by a truck. It is much more extended in one direction than in the other and so looks squashed on one side even after accounting for its inclined projection on the sky. This may be due to the motion of the host star plowing through the interstellar medium, like the bow wave from a boat crossing a lake. Or it may be influenced by a tidal tug from the star’s red dwarf binary companion (HR 4796B), located at least 54 billion miles from the primary star.
“The dust distribution is a telltale sign of how dynamically interactive the inner system containing the ring is,” said Glenn Schneider of the University of Arizona, Tucson, who used Hubble’s Space Telescope Imaging Spectrograph (STIS) to probe and map the small dust particles in the outer reaches of the HR 4796A system, a survey that only Hubble’s sensitivity can accomplish.
“We cannot treat exoplanetary debris systems as simply being in isolation. Environmental effects, such as interactions with the interstellar medium and forces due to stellar companions, may have long-term implications for the evolution of such systems. The gross asymmetries of the outer dust field are telling us there are a lot of forces in play (beyond just host-star radiation pressure) that are moving the material around. We’ve seen effects like this in a few other systems, but here’s a case where we see a bunch of things going on at once,” Schneider further explained.
Though long hypothesised, the first evidence for a debris disk around any star was uncovered in 1983 with NASA’s Infrared Astronomical Satellite. Later photographs revealed an edge-on debris disk around the southern star Beta Pictoris. In the late 1990s, Hubble’s second-generation instruments, which had the capability of blocking out the glare of a central star, allowed many more disks to be photographed. Now, such debris rings are thought to be common around stars. About 40 such systems have been imaged to date, largely by Hubble.
Observing Highlights for the Sky
This Week
(March 11 -18, 2018)
This weekend's morning skies show a thinning crescent moon passing through the region where Mars, Saturn and Jupiter have held court for the past few months. Mars rises by 3 AM and is high in the SSE by the beginning of dawn.
Sunday, March 11
For most people in the United States and Canada, daylight saving time begins at 2 a.m. local time this morning. Set your clocks ahead one hour.
The Moon reaches apogee, the farthest point in its orbit around Earth, at 5:14 a.m. EDT. It then lies 251,455 miles (404,678 kilometers) from Earth’s center.
Monday, March 12
Mars’ eastward motion relative to the background stars carries it from Ophiuchus into Sagittarius today. The magnitude 0.6 Red Planet rises around 3 a.m. local daylight time and climbs some 25° high in the south-southeast by the time twilight begins. Although the passage from Ophiuchus into Sagittarius is little more than a technical milestone, it does set up a series of pretty conjunctions with some of the Archer’s deep-sky gems starting next week.
Tuesday, March 13
Head outside before dawn and you can’t miss Jupiter. The giant planet rises around midnight local daylight time and climbs highest in the south around 5 a.m. Jupiter shines at magnitude –2.2, which makes it the brightest point of light in the predawn sky, and resides among the much dimmer stars of the constellation Libra. A telescope reveals the planet’s 40"-diameter disk and plenty of detail in the gas giant’s cloud tops.
Jupiter is high in the early morning sky in the south this week, allowing crisp details in its cloud structure to be visible even is small-to-moderate telescopes. Visible in this image along with the gas giant are moons Europa and Io. Image: Terry Robinson
Wednesday, March 14As midnight approaches, look to the east for the bright star Arcturus. At magnitude 0.0, it is the second-brightest star visible from mid-northern latitudes. If you look about 20° to the left and a little below this luminary, you should see a conspicuous semicircle of stars — the constellation Corona Borealis the Northern Crown. It’s the most prominent group of stars having a shape reminiscent of a circle, and it makes a fitting target for Pi Day. (For you non-geeks, Pi Day is 3/14 because the first three digits of the mathematical constant pi are 3.14. Pi is the ratio of a circle’s circumference to its diameter, so today we celebrate all things circular.)For those of you in the Southern Hemisphere, today marks the peak of the annual Gamma Normid meteor shower. The shower’s radiant — the point from which the meteors appear to originate — lies among the background stars of the southern constellation Norma the Square. This region lies below the horizon for observers north of 40° north latitude, but those farther south should keep their eyes open. The best views will come after midnight, once the radiant climbs higher. Fortunately, the waning crescent Moon sheds little light into the predawn sky. The shower typically produces about 6 meteors per hour at its peak.Thursday, March 15Mercury reaches greatest elongation at 11 a.m. EDT, and tonight marks the peak of its best evening apparition of 2018 for Northern Hemisphere observers. The innermost planet lies 18° east of the Sun and stands 12° high in the west a half-hour after sunset. It shines at magnitude –0.4 and shows up well against the darkening sky. But the easiest way to find it is to locate brilliant Venus and then look 4° to the upper right. The two inner planets fit nicely in a single binocular field of view. A view of Mercury through a telescope reveals an 7"-diameter disk that appears slightly less than half-lit. (Venus spans 10" and is nearly full.)
Use brilliant Venus as a guide to locating Mercury as it reaches its peak altitude for the year in mid-March.
Friday, March 16
One of the sky’s largest asterisms — a recognizable pattern of stars separate from a constellation’s form — occupies center stage after darkness falls on March evenings. To trace the so-called Winter Hexagon, start with southern Orion’s luminary, Rigel. From there, the hexagon makes a clockwise loop. The second stop is brilliant Sirius in Canis Major. Next, pick up Procyon in the faint constellation Canis Minor, then the twins Castor and Pollux in Gemini, followed by Capella in Auriga, Aldebaran in Taurus, and finally back to Rigel.
Saturday, March 17
New Moon occurs at 9:12 a.m. EDT. At its New phase, the Moon crosses the sky with the Sun and so remains hidden in our star’s glare.
Mercury and Venus have their second close conjunction of March this evening. Innermost Mercury passes 4° due north (upper right) of its neighbor at 9 p.m. EDT.
Sunday, March 18
With an age of 4.5 billion years, “young” might not seem an appropriate word to describe our Moon. But tonight, you have an exceptional opportunity to see what astronomers call a “young Moon” — a slender crescent visible in the early evening sky. With New Moon having occurred yesterday morning, only 2 percent of our satellite’s disk appears illuminated after sunset tonight. It forms a spectacular trio with Venus 4° to its right and Mercury 4° farther away. You should notice an ashen light faintly illuminating the Moon’s dark side. This is “earthshine,” sunlight reflected by Earth that reaches the Moon and then reflects back to our waiting eyes.
Supermassive Black Holes Growing Faster Than Expected (March 4, 2018)
New studies using NASA’s Chandra X-Ray Observatory, the Hubble Space Telescope and other observatories indicate that supermassive black holes are growing much faster than the rate of star formation in the massive galaxies that host them.
Earlier observations led astronomers to believe the rates of galactic star formation and the growth of supermassive black holes, those with millions to billions of times the mass of the Sun, marched in tandem.
In a surprise, new data indicate supermassive black holes at the hearts of giant galaxies are growing faster than the rate of star formation in their host galaxies. Image: NASA/CXC
But data from Chandra, Hubble and other telescopes shows the black holes lurking at the hearts of massive galaxies are growing much faster than those in less massive star swarms. In fact, the ratio between a supermassive black hole’s growth and the growth rate of stars in the host galaxy is 10 roughly times higher in galaxies with 100 billion solar masses compared to galaxies with about 10 billion solar masses.
“We are trying to reconstruct a race that started billions of years ago,” Guang Yang, a researcher at Pennsylvania State University who led one of two studies on black hole growth rates, said in a Chandra release. “We are using extraordinary data taken from different telescopes to figure out how this cosmic competition unfolded.”
Said co-author Niel Brandt, also of Penn State: “An obvious question is why? Maybe massive galaxies are more effective at feeding cold gas to their central supermassive black holes than less massive ones.”
Yang, Brandt and their colleagues studied black hole in galaxies at distance of 4.3 to 12.2 billion light years. A second group of researchers independently reached the same conclusion studying 72 galaxies in clusters up to about 3.5 billion light years from Earth using an established relationship between the mass of a black hole and its X-ray and radio emissions
“We found black holes that are far bigger than we expected,” said Mar Mezcua, of the Institut of Space Sciences in Spain. “Maybe they got a head start in this race to grow, or maybe they’ve had an edge in speed of growth that’s lasted billions of years.”
Almost half of the black holes in their sample were estimated to be at least 10 billion times the mass of the Sun, placing them in the “ultramassive” weight class.
Supermassive Black Hole Chows Down (December 1, 2015)
Don't ask me to pick up the tab for S5 0716+71 — no way can I afford its voracious appetite. With no warning, this otherwise fastidious and faint stellar pinpoint in the circumpolar constellation Camelopardalis rose from magnitude +13.7 to +12.5 within a week. A sure sign it's feeding again. The cause of this sudden surge in brightness is a supermassive black hole feasting on matter from its host galaxy, an invisible bit of fluff located 3.75 billion light-years from home in Camelopardalis.
This artist's concept shows a "feeding," or active, supermassive black hole, accretion disk, and a jet streaming outward at nearly the speed of light. Not all black holes have jets, but when they do, the jets can be pointed in any direction. If a jet happens to shine at Earth, the object is called a blazar. When seen from the side, it's a quasar.
NASA / JPL-Caltech
S5 0716+71 belongs to a class of violently-variable, active galactic nuclei (AGN) called blazars. Like quasars, blazars begin with a supermassive black hole at the center of a distant galaxy feeding on interstellar dust, rogue planets, and the occasional stray star. As the doomed object falls into the gravitational trap, it's shredded, compressed, and heated to millions of degrees to join its cohorts in a swirling vortex or accretion disk centered on the black hole. S5 0716+71 is the blue star-like object at center of this 14′ x 14′ wide photo chart. Its current bright outburst started at the end of October. Its host galaxy, 5.4 arcseconds in diameter, is too faint to see even in large telescopes. DSS2 / Stefan KargeMuch of the material within the disk ultimately spirals down the hole, but some of it gets whipped up by powerful magnetic fields generated within the rapidly spinning disk into a pair of relativistic jets. Any matter caught within a jet gets blasted hundreds of thousands of light years into space at 95 to 99% the speed of light.
S5 0716+71 is the blue star-like object at center of this 14′ x 14′ wide photo chart. Its current bright outburst started at the end of October. Its host galaxy, 5.4 arcseconds in diameter, is too faint to see even in large telescopes.
DSS2 / Stefan Karge
We now understand blazars and quasars as two sides of the same coin: In a quasar, we view the AGN from the side; in a blazar we stare directly or nearly so into the jet. Observing a blazar is akin to someone shining a flashlight right in your face. Because we see the jet almost square on, blobs of material within it can exhibit superluminal motion. As they travel toward us at nearly the speed of light, they keep pace with the light they emit. From our perspective, the difference in time of arrival between the two happens over a much shorter time frame, creating the illusion of faster-than-light travel. In October 2011, a team of astronomers observed a superluminal knot of material in S5 0716+71 traveling at an apparent speed ~21 times light speed! Comet Catalina C/2013 Finally Visible for Northern Observers! (November 20, 2015)
by Bob King
Click on the image for a better view. Comet Catalina C/2013 has finally popped into view in deep morning twilight in the eastern sky after passing through its closest approach to the sun back on November 15th. In this image, the comet was photographed from high atop the Himalayas by Ajay Talwar with a 200mm lens on a tracking mount early on the morning of Nov. 20, 2015. Copyright: Ajay Talwar
If you love watching comets and live north of the equator, you’ve been holding your breath a l-o-n-g time for C/2013 US10 Catalina to make its northern debut. I’m thrilled to report the wait is over. The comet just passed perihelion on Nov. 15th and has begun its climb into morning twilight.
The first post-perihelion photo, taken on Nov. 19th by astrophotographer Ajay Talwar from Devasthal Observatory high in the Indian Himalayas, show it as a starry dot with a hint of a tail only 1° above the eastern horizon at mid-twilight. Additional photos made on the following mornings show the comet inching up from the eastern horizon into better view. Estimates of its current brightness range from magnitude +6.8-7.0.
Sometimes black and white is better. This is the same chart as above but in a handier version for use at the telescope. Source: Chris Marriott’s SkyMap
Talwar, who teaches astrophotography classes and is a regular contributor to The World at Night (TWAN), drove 9 hours from his home to the Himalaya mountains, then climbed up the observatory dome to get enough horizon to photograph the comet. The window of opportunity was very narrow; Talwar had only 10 minutes to bag his images before the comet was overwhelmed by zodiacal light and twilight glow. When asked if it was visible in binoculars, he thought it would be but had too little time to check despite bringing a pair along.
Even before perihelion, Comet Catalina was a beautiful thing. This photo was taken on October 1, 2015 by Jose Chambo.
A difficult object at the moment, once it frees itself from the horizon haze in about a week, Catalina should be easily visible in ordinary binoculars. Watch for it to gradually brighten through the end of the year, peaking around magnitude +5 in late December and early January, when it will be well-placed high in the northeastern sky near the star Arcturus (see map). Matter of fact, on the first morning of the new year, it creeps only 1/2° southwest of the star for a splendid conjunction.
Comet C/2013 US10 Catalina will slice through the plane of the Solar System at an angle of 149° never to return. It comes closest to Earth on Jan. 12, 2016. After that time, the comet will recede and fade. Credit: JPL Horizons
Halloween 2013 was an auspicious one. That’s when Comet C/2013 US10 was first picked up by the Catalina Sky Survey. The “US10” part comes from initial observations that suggested it was an asteroid. Additional photos and observations instead revealed a fuzzy comet on a steeply tilted orbit headed for the inner Solar System after a long sojourn in the Oort Cloud.
Its sun-ward journey has been nothing short of legendary, requiring several million years of inbound travel from the frigid fringe to the relative warmth of the inner Solar System. Catalina will pass closest to Earth on Jan. 12th at 66.9 million miles (107.7 million km) before buzzing off into interstellar space. Yes, interstellar. Perturbations by the planets have converted its orbit into a one-way ticket out of here.
Check this out! Look to the east at the start of dawn on Dec. 7th to see a remarkable pairing of comet, Venus and the waning lunar crescent with earthshine. Source: Stellarium
When using the maps above, keep in mind they show the comet’s changing position, but the constellations and planets can only be shown for the one date, Nov. 21st. Like the comet, they’ll also be slowly sliding upward in the coming days and mornings due to Earth’s revolution around the Sun; stars that are near the horizon on Nov. 21 at 5:30 or 6 a.m. will be considerably higher up in a darker sky by the same time in December. Adding the shift of the stars to that of the comet, Catalina gains about 1° of altitude per day in the coming two weeks.
When you go out to find Catalina in binoculars, note its location on the map and then use the stars as steppingstones, starting with a bright obvious one like Spica and “stepping” from there to the next until you arrive at the one closest to the comet.
I’m so looking forward to finding Catalina. Nothing like a potentially naked eye comet to warm up those cold December mornings. Mark your calendar for the morning of Dec. 7th, when this rare visitor will join Venus and the crescent Moon in the east at the start of morning twilight. See you in spirit at dawn!
Artificial Object in Trans-lunar Orbit to Impact Earth on November 13 (November 2, 2015)
by Bob King
Get ready for a man-made fireball. A object discovered by the Catalina Sky Survey on Oct 3rd temporarily designated WT1190F is predicted to impact the Earth about 60 miles (100 km) of the southern coast of Sri Lanka around 6:20 Universal Time (12:20 a.m CST) on November 13. The objects orbits Earth with a period of about three weeks. Because it was also observed twice in 2013 by the same survey team, astronomers have the data they need to model its orbit and trajectory, and as far anyone can tell, it’s likely man-made.
Solar radiation pressure, the physical “push” exerted by photons of sunlight, is proportional to a space object’s area-to-mass ratio. Small, lightweight objects get pushed around more easily than heavier, denser ones. Taking that factor into account in examining WT1190F’s motion over two years, the survey team has indirectly measured WT1190F’s density at about 10% that of water. This is too low to be a typical asteroid made of rock, but a good fit with a hollow shell, possibly the upper stage of a rocket.
It’s also quite small, at most only about six feet or a couple of meters in diameter. Most or all of it is likely to burn up upon re-entry, creating a spectacular show for anyone near the scene. During the next week and a half, the European Space Agency’s NEO (Near-Earth Object) Coordination Center is organizing observing campaigns to collect as much data as possible on the object, according to a posting on their website. The agency has two goals: to better understand satellite re-entries from high orbits and to use the opportunity to test our readiness for a possible future event involving a real asteroid. The latter happened once before when 2008 TC3 (a real asteroid) was spotted on October 6, 2008 and predicted to strike Earth the very next day. Incredibly, it did and peppered the Sudan with meteorites that were later recovered.
Assuming WT1190F is artificial, its trans-lunar orbit (orbit that carries it beyond the Moon) hints at several possibilities. Third stages from the Saturn-V rockets that launched the Apollo missions to the Moon are still out there. It could also be a stage from one of the old Russian or more recent Chinese lunar missions. Even rockets used to give interplanetary probes a final push are game.
Case in point. What was thought initially to be anew asteroid discovered by amateur astronomer Bill Yeung on September 3, 2002 proved a much better fit with an Apollo 12 S-IVB (third) stage after University of Arizona astronomers found that spectra taken of the object strongly correlated with absorption features seen in a combination of man-made materials including white paint, black paint, and aluminum, all consistent with Saturn V rockets.
Apollo 13’s booster was the first deliberately crashed into the Moon, where it blew out it a crisp, 98-foot-wide (30-meter) crater. Why do such a crazy thing? What better way to test the seismometers left by the Apollo 12 crew? All subsequent boosters ended their lives similarly in the name of seismography. Third stages from earlier missions — Apollos 8, 10 and 11 — entered orbit around the Sun, while Apollo 12, which orbiting Earth, briefly masqueraded as asteroid J002E3.
Bill Gray at Project Pluto has a page up about the November 13 impact of WT1190F with more information. Satellite and asteroid watchers are hoping to track the object before and right up until it burns up in the atmosphere. Currently, it’s extremely faint and moving eastward in Orion. You can click HERE for an ephemeris giving its position at the JPL Horizons site. How exciting if we could see whatever’s coming down before its demise on Friday the 13th!
Planets Meet in the Morning Sky
(September 29, 2015)
Planets are gathering in the morning sky. Venus and Jupiter have recently emerged as morning "stars," rising in the east ahead of the sun, joining Mars in an array of lights that lets early risers view 1/3rd of the solar system at a glance. The display will continue--and improve--as autumn unfolds. This was the view on Sept. 10th:
Jean-Baptiste Feldmann took the picture from Nuits-Saint-Georges, France, just before sunrise on Thursday. At the time, the crescent Moon was passing by Venus en route to Jupiter, adding its luster to that of the planets. "It was a beautiful view," says Feldmann.
More scenes like this are in the offing. On Oct. 8th the crescent Moon will have another close encounter with Venus (sky map), followed one day later by a near miss of Jupiter and Mars (sky map). Every morning thereafter, the planets will converge until Oct. 24th - Oct. 29th when they fit within a circle only 5o wide (sky maps: #1, #2, #3, #4, #5, #6). Typical binoculars can see a patch of sky about 6o or 7o degrees wide. So when the triangle of planets shrinks to 5o, they will fit together inside a binocular field of view. Imagine looking through the eyepiece and seeing three planets--all at once.
By the time October comes to an end, the planetary triangle will start breaking apart. But there are still two dates of special interest: Nov. 6th and 7th (sky maps:#1, #2). On those increasingly wintry mornings, the crescent Moon will swoop in among the dispersing planets for a loose but beautiful conjunction.
Look east before sunrise. There's a lot to see.
Comet 67P Churyumov-Gerasimenko Reaching Peak Brightness - Visible in Amateur Telescopes! (August 24, 2015)
We've waited a long time for this. Looked at hundreds of close-up photos of Comet 67P/Churyumov-Gerasimenko taken by the Rosetta spacecraft since it arrived at the comet a year ago this month. Now it's time to put real comet photons in our eyes. Right here. On Earth.
During this perihelion week up through early next month, 67P/C-G will crest at around magnitude +12 in the pre-dawn sky. This week, the pesky but ravishing crescent Moon transitions to the evening sky, leaving mornings free to track down the comet under dark skies.
67P/C-G canters across Gemini this month and early next, favoring Northern Hemisphere skywatchers, though not by much! Observers with big Dobs will more than likely have to assume the "praying position" with knees on the ground for a good look. I know I did. But it was worth every bit of strain.
Comet 67P/Churyumov-Gerasimenko photographed on August 9, 2015. The comet is a small, 12th magnitude, moderately condensed fuzzball in amateur telescopes. Photographs show a short tail trailing to the west.
Efrain Morales
Amateur astronomers participating in the Pro-Amateur Collaborative Astronomy (PACA) campaign have been following the comet since March 2014 when it glowed at an anemic magnitude +21. After solar conjunction on Feb. 10, 2015, it was recovered in mid-April low in the morning sky at 17th magnitude. 67P/C-G continued to slowly brighten through the spring and early summer en route to its August 13th perihelion. One of the first visual observations of the comet was made by Chris Wyatt of Walcha, New South Wales, Australia, who called it diffuse, about 30″ across, and magnitude 14.2 on June 23rd.Since then, the trickle of Earth-based observations has quickly become a flood as amateurs and professionals alike take advantage of the incredible opportunity to coordinate their visual observations, photos and spectra with Rosetta's in-situ measurements. If you'd like to join the campaign, there's no time like now. Sign up right here.
Comet 67P/Churyumov-Gerasimenko's path parallels the ecliptic. This map shows its location from mid-July to late November as seen from the northern hemisphere. The comet remains a morning sky object throughout.
Source: Chris Marriott's SkyMap
From my latitude of +42°, long summer twilights, a small elongation, and extreme faintness kept the comet off-limits until last weekend. But from here on out, it's smooth sailing as the famed fuzzy iceberg climbs higher and higher up the dark sky ladder during late summer and fall. The moonless periods from August 12-27 and Sept. 10-26 will be your best times to look. By late September, 67P/C-G will still be visible but fading, as its distance from the Sun continues to increase.
Light curve and prediction of Comet 67P's brightness from Seiichi Yoshida's Weekly Comet Information site. In his updated analysis, the comet will peak around magnitude +12 later this month. The horizontal axis shows the date; the vertical the magnitude.
Seiichi Yoshida
While the comet rises by 3:30 AM now, it is best to wait for it to rise out of the eastern horizon haze. By the time dawn's light first makes its faint presence known early these mornings (~4:50 AM) the comet is now a user-friendly 16° high and the view has sharpened with the comet much more distinct. Using a magnification to 245x with my 8" Schmitt-Cassegrain reflector on Sunday morning, I saw a moderately condensed, round, milky glow about 0.7′ across with a magnitude of +12.5. That lovely little tadpole tail that shows so well in recent photos was sadly beyond my scope and these eyes.
Comet observers often describe how dense or bright a comet appears using a degree of condensation (DC) scale numbered from 0 to 9, with a DC of 0 being a flat profile coma with no central brightening and a DC of 9 being a completely stellar object. 67P/C-G's current DC is 4 or 5, depending on the observer and equipment.
Back on August 6th, the comet joined Gemini's bright star cluster M35.
Rolando Ligustri
Realizing that the Rosetta spacecraft was buried somewhere within the comet's coma gave me the greatest thrill. That and watching it crawl eastward among the stars like some fuzzy caterpillar looking for a meal. To my surprise, high power revealed motion in just 20 minutes. Watching an object like a comet or asteroid move against the stars adds excitement to an observation and makes it that much more real.
As of August 24th, the comet is located near the center of the constellation Gemini and is moving eastward.
Here is a more detailed finder chart of the comet's location for the last half of August 2015. Click on the image for a much larger PDF version.
Jupiter and Venus Hook Up! (June 30, 2015)
Look up! The brightest and best planet pairing of the year is underway in the western sky at dusk. Venus and Jupiter have been near one another for months; they’ll finally squeeze closest together tomorrow night (June 30). But you needn’t wait till then. Tonight, the dynamic duo will be just over 1/2° apart, the width of a full moon. Plenty tight.
Seeing the the solar system’s two brightest planets side by side will make for a fantastic sight at dusk. You can start watching shortly after sunset, but they’ll appear most dramatic in a darker sky an hour to 75 minutes later.
Closest approach occurs tomorrow evening when Venus and Jupiter will be just two-thirds of a moon diameter apart. Your little finger extended at arm’s length covers 1° of sky or twice the width of a full moon. Not until Friday will the two planets pull far enough apart again to fit your pinkie between them. Give it a try.
The view facing west-northwest about 50 minutes after sunset on June 30 when Venus and Jupiter will be at their closest. Two celestial bodies are said to be in conjunction when they have the same right ascension or “longitude”and line up one atop the other. Source: Stellarium
When two planets or a combination of moon and planets align closely in the sky, they’re in conjunction. Lots of conjunctions happen every year. Heck, the moon’s in conjunction with each of the seven planets once a month. What makes this one special is that it involves the two brightest planets in an especially close conjunction. These happen more rarely, and we can’t help but be drawn in. Shiny alignments catch the eye. More than that, they’re beautiful to behold like wild orchids in the forest.
Clouds expected tomorrow night? The conjunction will be nearly as fine tonight and July 1. Times and separations shown for central North America at 10 p.m. CDT. 30 minutes of arc or 30′ equals one Full Moon diameter. Source: Stellarium - CLICK TO ENLARGE.
You can take in the conjunction with the naked eye, binoculars or telescope. Because Venus and Jupiter are so close, those with even the smallest telescopes will experience the unique pleasure of seeing both in the same magnified field of view. Though Jupiter is currently 11 times farther from Earth than Venus, they have the same apparent size because Jove is so much larger.
Venus goes through phases like the moon and will look like a brilliant white crescent. Be sure to look for Jupiter’s four brightest moons on eithe side of the planet tomorrow evening.
The view through a small telescope of Jupiter (top) and Venus on June 30 around 9:30 p.m. CDT. Jupiter’s moons are G = Ganymede, E = Europa, I = Io and C = Callisto. Source: Stellarium
To capture an image of our planetary pals try using your cellphone. First, find a pretty scene to frame the pair. Hold your phone rock-solid steady against a post or building and click away starting about an hour after sundown when the two planets have good contrast with the sky, but with light still about. If your pictures appear too dark or light, manually adjust the exposure. Here’s a youtube video on how to do it with an iPhone.
Point-and-shoot camera owners should place their camera on a tripod, adjust the ISO or sensitivity to 100, open the aperture or f/stop to its widest setting (f/2.8 or f/4), autofocus on the planets and expose from 5-10 seconds in mid-twilight or about 1 hour to 90 minutes after sunset. The low ISO is necessary to keep the images from turning grainy. High-end digital SLR cameras have no such limitations and can be used at ISO 1600 or higher. As always, review the back screen to make sure you’re exposing properly.
Wishing you clear skies as always!
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New Juno findings amaze scientists studying Jupiter (March 7, 2018) by Kelly Beatty
A dramatic infrared view of Jupiter’s north pole, showing a central storm surrounded by eight closely-packed cyclones. Similar, even larger, storms are seen at the south pole. Image: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
New findings from NASA’s Juno spacecraft show Jupiter’s weather systems extend much deeper than previously believed and that the huge planet rotates nearly as a rigid body below the racing jet streams, storms and cyclones.
“This is really an amazing result, and future measurements by Juno will help us understand how the transition works between the weather layer and the rigid body below,” Tristan Guillot, a Juno co-investigator from the Université Côte d’Azur, Nice, France, said in a NASA release. Guillot is the lead author of a paper on Jupiter’s deep interior published in the March 8 issue of the journal Nature.
“Juno’s discovery has implications for other worlds in our solar system and beyond,” he said. “Our results imply that the outer differentially-rotating region should be at least three times deeper in Saturn and shallower in massive giant planets and brown dwarf stars.”
How deep Jupiter’s familiar cloud belts and zones extend has been a mystery for decades, but precise measurements of the planet’s gravity field, the subject of another paper in Nature, show the weather layer, from its top to a depth of some 3,000 kilometres (1,900 miles), contains about three Earth masses of material, or about 1 percent of Jupiter’s total mass.
Exoplanet Proxima Centauri b Had a Very Bad Day (March 1, 2018)
On 24 March last year, a planet – Proxima b – orbiting the red dwarf Proxima Centauri, the Sun’s nearest stellar neighbour, had a very, very bad day.
Two powerful solar flares erupted in two minutes, the second one 10 times brighter than any known flare from Earth’s sun, increasing Proxima Centauri’s brightness by 1,000 times in just 10 seconds and blasting Proxima b with 4,000 times more radiation than Earth receives from a major outburst.
The huge flare, and a smaller one that preceded it, was discovered by the Carnegie Institution’s Meredith MacGregor and Alycia Weinberger when they reviewed observations made last year by the Atacama Large Millimeter/submillimeter Array, or ALMA, radio telescope. Proxima Centauri, known as a fare star, is the Sun’s nearest stellar neighbour at a distance of 4.2 light years.
“It’s likely that Proxima b was blasted by high energy radiation during the flare,” MacGregor said in a Carnegie statement. “Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilized the surface, suggesting that habitability may involve more than just being the right distance from the host star to have liquid water.”
Proxima b, with a mass of at least 1.3 times that of Earth, orbits its sun at a distance of about 7.5 million kilometers (4.6 million miles), completing one “year” in a bit more than 11 days. The planet orbits in the red dwarf’s habitable zone, but astronomers already doubted its habitability because of the star’s extreme solar wind and history of flares.
A paper last November looked at the same ALMA observations and concluded the average brightness, including the output of the star and the flare, may have been caused by disks of dust and debris circling Proxima Centauri that are similar to the asteroid and Kuiper belts in Earth’s solar system, possibly indicating the presence of additional planets.
But when MacGregor, Weinberger and their team looked at the data as a function of observing time, the nature of the transient event became clear, according to the Carnegie statement.
“There is now no reason to think that there is a substantial amount of dust around Proxima Cen,” Weinberger said. “Nor is there any information yet that indicates the star has a rich planetary system like ours.”
Last Chance to See Doomed Chinese Space Station (March 7, 2018) By: Bob King
Don't look now, but a whole lotta metal will be falling out of the sky. Soon. And we're not talking meteorites. China's Tiangong 1 space station is staring down its final weeks with re-entry predicted sometime between March 24th and April 19th. Of late, the 8.5-ton spacecraft has been losing altitude at the rate of 6 kilometers a week from atmospheric drag. Although it's impossible to predict even an approximate landing site until hours before re-entry, Tiangong 1's orbital inclination makes anywhere between 43°N and 43°S fair game.
An artist's conception of Tiangong-1 in orbit. It's likely that pieces of the craft will survive re-entry later this month.
CMSE / China Space Engineering Office
Launched in September 2011, Tiangong 1 (Chinese for "heavenly palace") was China's first space station. After several successful manned and unmanned missions, Chinese National Space Administration (CNSA) officials extended the spacecraft's life for two years until they lost telemetry in March 2016. By June of that year, amateur satellite watchers reported that the station was out of control, a fact that the CNSA finally conceded three months later.The original plan was to de-orbit the space station with a controlled thruster burn for a safe breakup over the Pacific Ocean. But without telemetry, the craft can no longer be controlled, so re-entry depends entirely on the vagaries of atmospheric drag complicated by the effects of Sun-driven space weather.
Tiangong 1 glides through Orion over Williamsburg, Virginia. Watch for it to make similar passes for a short time before burning up on re-entry later this month or early next. As its loses altitude, drag from friction with the atmosphere causes the satellite to lose even more altitude, creating more drag and leading to its inevitable demise.
Chris Becke (@BeckePhysics)
Not until hours before re-entry will we have a good idea of where heaven will meet earth. Although it can fall anywhere within the zone mentioned earlier, the California-based Aerospace Corporation predicts a higher probability in either of two narrow belts of latitude from ~39°N to 43°N and ~39°S to 43°S. In the southern hemisphere, these latitudes include sections of Chile, Argentina, Tasmania, and New Zealand. In the northern, Italy, Spain, and a strip of U.S. states from New York to California lie within this preferred path.Chances are that any surviving fragments will fall in the ocean, but there's always a tiny possibility pieces could slam into the ground where they might be recovered. Getting hit by a human-made "meteorite" is exceedingly rare, with odds estimated at about one in a trillion. You're a million times more likely to win the Powerball jackpot. In all of spaceflight history only one person has ever been struck by space junk. That would be Lottie Williams of Tulsa on January 22, 1997. She was 48 at the time and out on an early morning walk when a metal fragment of a re-entering Delta II rocket struck her left shoulder with a glancing blow. She was not injured.
If still in orbit on March 31st, people in the Windsor area will get there first chance in several weeks (and probably last chance overall) to see the space station as it crosses the early morning sky. To see it, be out a minute or two before 6:39:51 am EDT, where it will appear 10 degrees up from the horizon in the SW, moving northeastward at visual magnitude 1.3. It will be visible for about 4-5 minutes, disappearing in the early glow of sunrise in the east.
Before Tiangong 1 hits the drink, observers in the southern and eastern U.S. and other locations have several chances to see it. This week through the middle of next (about March 13th), the doomed station will make 1–3-minute-long passes during convenient evening viewing hours. Unfortunately, for those in the Windsor region, our best chance to see the satellite will only come if it maintains orbit past March 31st - that morning it will be visible in the south just after 6:39 am EDT (see photo caption). Tiangong 1's magnitude will vary from as bright as 0.2 to as faint as 4 depending on the altitude of the pass. The higher, the brighter.After the 13th (give or take), the satellite will move into the daytime sky and then reappear at dawn sky at the end of March. The dawn run concludes about April 10th. Should Tiangong 1 still be in orbit after that date, it will return to the evening sky in mid-April.To find out when and where to look from your location, go to Heavens Above and login. If you're not registered, you can still click the Change Your Observing Location link in the column on the left side of the opening page to add your city. Then return to the opening page and click the Tiangong 1 link to get a table of upcoming passes. If you click the date link, a map showing its path pops up. Because of its evolving orbit, pass times may vary a bit. The space station will look just like a star moving from west to east across the sky.Maybe, just maybe you'll get to see its transformation from a point of light to a slow-moving fireball when it finally plummets to Earth. If you're exceptionally lucky, a piece might just show up in your backyard. Leave it be, as experts believe there's still toxic hydrazine propellant on board.Speaking of satellites, this is also the month that Humanity Star begins making evening passes from many northern hemisphere locations. Follow the same directions as you did for Tiangong 1 but click on the Humanity Star link to get times and maps. Despite initial predictions, the flashing satellite isn't expected to shine brighter than 4th magnitude. **Update: I got eyes on this satellite for the first time on March 10.1 UT, when I spotted it in binoculars just west of the Pleiades. Humanity Star was on schedule and exhibited bright, quick flashes of varying magnitude. I next lowered the binoculars and found it with just my eyes. The brightest flashes were about magnitude 2. Pops like a strobe!
Cast your gaze wide to see the zodiacal light. The wedge is large and broad at the bottom and stands easily six fists high. It begins to the left of the Pegasus Square and tilts upward and left through Pisces, Aries, and Taurus. Its name comes from "zodiac" because the glow follows the ecliptic through the zodiac constellations.
Stellarium
As long as you're watching for satellites, keep an eye out for the zodiacal light, especially if you have access to a dark sky. Evenings are moonless now and March through early April are peak times to see this big, fuzzy cloud of comet and asteroid dust. Face west from 1½–2 hours after sunset and look for a tapering cone of soft, diffuse light reaching up from low in the western sky past the Pleiades and through Taurus until it tickles the toes of the Gemini Twins. The cone is broader and brighter — at least as bright as the summer Milky Way — at its base and fades and tapers the higher you look.Dust boiled off comets cycling around the Sun is the major contributor to the zodiacal light, but colliding asteroids provide material, too. The dust gathers in a vast cloud that extends at least to Jupiter and reveals its presence by scattering sunlight. Plan a drive to the country to see it best. Skies will be moonless now through March 18–19. Don't miss the sight of one of the largest entities in the solar system.
Scientists See a Full Day on Pluto and Charon (November 19, 2015) by Nancy Atkinson
On approach in July 2015, the cameras on NASA’s New Horizons spacecraft captured Pluto rotating over the course of a full “Pluto day.” The best available images of each side of Pluto taken during approach have been combined to create this view of a full rotation. Credit: NASA/JHUAPL/SwRI.
A day on Pluto is 6.4 Earth days (6 days 9 hours and 36 minutes) long. That’s a lengthy, cold, and rather dark day. But this new image released by the New Horizons spacecraft team gives us a better idea of what a day on Pluto might be like. This montage of images shows Pluto rotating over the course of a full Pluto day.
It is interesting to note that Pluto’s moon Charon is tidally locked around Pluto, so this means that Charon takes 6.4 Earth days to orbit around Pluto – the same amount of time as a day on Pluto. If you were standing on Pluto, Charon would always be at the same place in the sky, or you wouldn’t be able to see it at all. And vise versa if you were on Charon.
New Horizons also captured a full day rotation for Charon, too, which you can see below.
On approach to the Pluto system in July 2015, the cameras on NASA’s New Horizons spacecraft captured images of the largest of Pluto’s five moons, Charon, rotating over the course of a full day. The best currently available images of each side of Charon taken during approach have been combined to create this view of a full rotation of the moon. Credit: NASA/JHUAPL/SwRI.
The images were taken by the Long Range Reconnaissance Imager (LORRI) and the Ralph/Multispectral Visible Imaging Camera as New Horizons zoomed toward the Pluto system, and in the various images the distance between New Horizons and Pluto decreased from 5 million miles (8 million kilometers) on July 7 to 400,000 miles (about 645,000 kilometers) on July 13, 2015.
The science team explained that in the Pluto montage, the more distant images are at the 12 to 3 o’clock position, and so these are the best views we have of the peculiar “bumps” or impact craters on the far side. The side New Horizons saw in most detail – what the mission team calls the “encounter hemisphere” – is at the 6 o’clock position. The most prevalent feature there is the heart-shaped, “Tombaugh Regio” area that made us all love Pluto even more. The odd shape of Pluto in the 12 and 1 o’clock position images aren’t lumps and deformities, but just artifacts from the way the images were combined to create these composites. For the Charon montage, the images at the 9 o’clock position were taken from the greatest distance, with few of the signature surface features visible, such as the cratered uplands, canyons, or rolling plains of the region informally named Vulcan Planum. The side New Horizons saw in most detail, during closest approach on July 14, 2015, is at the 12 o’clock position. As a comparison, below is a timelapse view of the Pluto-Charon orbital dance, which was taken by New Horizons back in January 2015. Pluto and Charon were observed for an entire rotation of each body, the same 6 days 9 hours and 36 minutes.
Pluto and Charon were observed by the New Horizons spacecraft for an entire rotation of each body; a “day” on Pluto and Charon is 6.4, which is Earth days. The first of the images was taken when New Horizons was about 3 billion miles from Earth, but just 126 million miles (203 million kilometers) from Pluto, on Jan. 25-31, 2015. NASA/APL/Southwest Research Institute.
Numerous Fireballs Reported as Taurid Meteor Stream Impacts Earth's Atmosphere
(November 5, 2015) by Tony Philips
There no longer any doubt. Earth is passing through a stream of gravelly debris from Comet Encke, source of the annual Taurid meteor shower. Meteoroids the size of pebbles, and larger, are disintegrating as they hit our planet's atmosphere at 30 km/s. To see what effect this is having on the night sky, Martin Popek of Nýdek (Czech republic) activated a low-light camera in his backyard and let it run all night long. This is what it recorded:
There were almost a dozen exploding meteors--all brighter than Venus and one as bright as a crescent Moon. "It was a very active night," says Popek. Earth runs unto the debris zone of Comet Encke every year around this time. Usually, the encounter produces a minor meteor shower, but 2015 is different. "This is higher than usual activity," says meteor expert Peter Brown of the University of Western Ontario. "The Canadian Meteor Orbit Radar ( CMOR) is seeing stronger Taurid activity than any of the last few years. Our Southern Ontario Meteor Network cameras caught 54 Taurid fireballs from Oct 31 - Nov 4 alone, compared to 22, 18, and 32 Taurids for the entire month of November in 2014, 2013 and 2012 respectively." These extra fireballs are coming from a "swarm" of gravelly meteoroids that weaves in and out of Comet Encke's dusty debris zone. In some years, Earth hits the swarm; in other years it misses. 2015 appears to be a hit. "I would say with some confidence the 2015 Taurid 'swarm' is active as predicted by astronomer David Asher," adds Brown. If those predictions continue to be correct, the fireball display could carry on until Nov. 10th. The best time to look, no matter where you live, is during the hours around local midnight when the constellation Taurus is high in the sky. [ meteor radar] On This Date, 150 Years Ago: Solar Mega Storm! (September 2, 2015) by Dr. Tony Philips
On Sept. 2nd, a billion-ton coronal mass ejection (CME) slammed into Earth's magnetic field. Campers in the Rocky Mountains woke up in the middle of the night, thinking that the glow they saw was sunrise. No, it was the Northern Lights. People in Cuba read their morning paper by the red illumination of aurora borealis. Earth was peppered by particles so energetic, they altered the chemistry of polar ice.
Hard to believe? It really happened--exactly 156 years ago. This map shows where auroras were sighted in the early hours of Sept. 2, 1859:
As the day unfolded, the gathering storm electrified telegraph lines, shocking technicians and setting their telegraph papers on fire. The "Victorian Internet" was knocked offline. Magnetometers around the world recorded strong disturbances in the planetary magnetic field for more than a week.
The cause of all this was an extraordinary solar flare witnessed the day before by British astronomer Richard Carrington. His sighting marked the discovery of solar flares and foreshadowed a new field of study: space weather. According to the National Academy of Sciences, if a similar storm occurred today, it would cause a trillion dollars in damage to society's high-tech infrastructure and require four to ten years for complete recovery.
In fact, a similar flare did occur just a few years ago. On July 23, 2012, a CME of rare power rocketed away from the sun. The storm was in all respects at least as strong as the 1859 Carrington event. The only difference is, it missed. no harm done. The July 2012 event serves as a reminder, however, that extreme space weather is not a thing of the past.
THE SUN SWALLOWS A COMET:
On Friday, Aug.28th, the sun swallowed a comet. The Solar and Heliospheric Observatory (SOHO) spotted the icy vistor from the outer solar system making a headlong plunge into our star. One comet went in; none came out. Click to play the movie:
Heated by the sun at point blank range, the comet's fragile ices vaporized, leaving at most a "rubble pile" of rock and gravel scattered along its sungrazing orbit. Any remains are invisible from Earth.
The comet, R.I.P., was probably a member of the Kreutz family. 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. Several Kreutz fragments pass by the sun and disintegrate every day. Most, measuring less than a few meters across, are too small to see, but occasionally a bigger fragment like this one (~10 m to 50 m) attracts attention.
Because of their common parentage, sungrazers often come in clusters. For this reason, it wouldn't be surprising to find yet another one in the offing. Monitor Karl Battam's Sungrazing Comet twitter feed for more sightings.
New Horizons Sees the Whole Pluto Family for the First Time (May 13, 2015) By Bob King
For the first time, NASA’s New Horizons spacecraft has photographed Pluto’s tiniest and faintest known moons, Kerberos and Styx. Kerberos circles the dwarf planet every 32 days and measures just 6 to 20 miles (~10 to 30 km) in diameter. Styx is even smaller at 4 to 13 miles (~ 7 to 21 km) across and orbits every 20 days. Incredibly, the specks of moons were detected from a distance of more than 55 million miles.
When you toss in Pluto’s largest moon, Charon, first seen by New Horizons in July 2013 and its two other smaller satellites, Nix and Hydra, spotted in July 2014 and January 2015 respectively, we’ve now seen all known members of Pluto’s family.
Anything else that pops up in images from now on will be gravy. That could well include new moons, Pluto rings or satellites of known moons.
“New Horizons is now on the threshold of discovery,” said mission science team member John Spencer, of the Southwest Research Institute in Boulder, Colorado. “If the spacecraft observes any additional moons as we get closer to Pluto, they will be worlds that no one has ever seen before.”
It won’t be long before the probe makes a dramatic flyby of the system on July 14. New Horizons will pass just 6,200 miles (10,000 km) from Pluto while traveling at 30,800 mph (49,600 km/hr) at closest approach at 6:50 a.m. Eastern Time. Because of Pluto’s great distance from the Sun, communications between the probe and Earth will take 4.5 hours, and that’s just one way moving at the speed of light.
Watch Venus Encounter the Pleiades This Week (April 7, 2015)
By Bob King, Astrobob@areavoices.com
Venus glides up to the Pleiades or Seven Sisters star cluster this week. This was the view at dusk on April 4 when they were still about 10° apart. Credit: Bob King
If you’ve ever been impressed by the brilliance of Venus or the pulchritude of the Pleiades, you won’t want to miss what’s happening in the western sky this week. Venus has been inching closer and closer to the star cluster for months. Come Friday and Saturday the two will be only 2.5° apart. What a fantastic sight they’ll make together — the sky’s brightest planet and arguably the most beautiful star cluster side by side at dusk.
No fancy equipment is required for a great view of their close conjunction. The naked eye will do, though I recommend binoculars; a pair of 7 x 35s or 10 x 50s will increase the number of stars you’ll see more than tenfold.
Map showing Venus’ path daily from April 6-15, 2015 as it makes a pass at the Pleiades. The close pairing will make for great photo opportunities . Created with Chris Marriott’s SkyMap
Just step outside between about 8:30 and 10 p.m. local time, face west and let Venus be your guide. At magnitude -4.1, it’s rivaled in brightness only by the Moon and Sun. Early this week, Venus will lie about 5° or three fingers held together at arm’s length below the Pleiades. But each day it snuggles up a little closer until closest approach on Friday. Around that time, you’ll be able to view both in the same binocular field. Outrageously bright Venus makes for a stunning contrast against the delicate pinpoint beauty of the star cluster.
Venus on April 3, 2012, when it last passed right in front of the Seven Sisters. The Pleiades is a young cluster dominated by hot, blue-white stars located 444 light years from Earth. Credit: Bob King
Every 8 years on mid-April evenings, Venus skirts the Pleiades just as it’s doing this week. Think back to April 2007 and you might remember a similar passage; a repeat will happen in April 2023. Venus’ cyclical visits to the Seven Sisters occur because the planet’s motion relative to the Sun repeats every 8 years as seen from Earth’s skies. No matter where and when you see Venus – morning or evening, high or low – you’ll see it in nearly the same place 8 years from that date.
But this is where it gets interesting. On closer inspection, we soon learn that not every Venus-Pleiades passage is an exact copy. There are actually 3 varieties:
* Close: Venus passes squarely in front of the cluster
* Mid-distance: Venus passes ~2.5° from the cluster
* Far: Venus passes ~3.5° from the cluster
And get this — each has its own 8-year cycle. This week’s event is part of a series of mid-distance passages that recurs every 8 years. Venus last passeddirectly through Pleiades in April 2012 and will again in April 2020. The next most distant meeting (3.5°) happens in April 2018 and will again in 2026.
Venus circles between Earth and the Sun and experiences phases just like the Moon from our perspective. The planet is currently in gibbous phase. It reaches its greatest apparent distance from the Sun on June 6 and inferior conjunction on August 15. Credit: Wikipedia with additions by the author
Why three flavors? Venus’ orbit is tipped 3.4° to the plane of the ecliptic or the Sun-Earth line. During each of it 8-year close passages, it’s furthest north of the ecliptic and crosses within the Pleiades, which by good fortune lie about 4° north of the ecliptic. During the other two cycles, Venus lies closer to the ecliptic and misses the cluster by a few degrees.
Fascinating that a few simple orbital quirks allow for an ever-changing variety of paths for Venus to take around (and through!) one of our favorite star clusters.
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