Vesta's surface textures get highlighted by dawn's light
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Sunrise on Vesta highlights the asteroid’s varied surface textures in this image from NASA’s Dawn spacecraft, released on Monday, Feb. 20. The image was taken on Dec. 18 with Dawn’s Framing Camera (FC).
Just as the low angle of early morning sunlight casts long shadows on Earth, sunrise on Vesta has the same effect — although on Vesta it’s not trees and buildings that are being illuminated but rather deep craters and chains of pits!
The steep inner wall of a crater is seen at lower right with several landslides visible, its outer ridge cutting a sharp line.
Chains of pits are visible in the center of the view. These features are the result of ejected material from an impact that occurred outside of the image area.
Other lower-profile, likely older craters remain in shadow.
Many of these features would appear much less dramatic with a high angle of illumination, but they really shine brightest in dawn’s light.
The orbit of asteroid 433 Eros brings it close to Earth on Jan. 31. (www.astronomerswithoutborders.org)
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As the bright Mars-crossing asteroid 433 Eros makes its closest approach to Earth since 1975, astronomers around the globe are taking the opportunity to measure its position in the sky, thereby fine-tuning our working knowledge of distances in the solar system. Using the optical principle of parallax, whereby different viewpoints of the same object show slightly shifted positions relative to background objects, skywatchers in different parts of the world can observe Eros over the next few nights and share their images online.
The endeavor is called the Eros Parallax Project, and you can participate too!
Discovered in 1898, Eros was the largest near-Earth asteroid yet identified. Its close and relatively bright oppositions were calculated by astronomers of the day and used, along with solar transits by Venus (one of which, if you haven’t heard, will also occur this year on June 5!) to calculate distances in the inner solar system.
Having both events take place within the same year offers today’s astronomers an unparalleled opportunity to obtain observational measurements.
Through the efforts of the Astronomers Without Borders organization, along with Steven van Roode and Michael Richmond from the Transit of Venus project, anyone with moderate astrophotography experience can participate in the observation of Eros and share their photos via free online software.
Using the data gathered by individual participants positioned around the world, each with their own specific viewpoints, astronomers will be able to precisely measure the distance to Eros.
The more accurately that distance is known, the more accurately the distance from Earth to the Sun can be calculated – via the orbital mechanics of Kepler’s third law.
The tumbling motion of elongated 33-km-long Eros creates a changing brightness. (via transitofvenus.nl)
The last time such a bright pass of Eros occurred was in January of 1931. Observations of the asteroid made at that time allowed astronomers to calculate a solar parallax of 8″ .790, the most accurate up to that time and the most accurate until 1968, when data acquired by radar measurements gave more detailed measurements.
In many ways the 2012 close approach by Eros – astronomically close, but still a very safe 16.6 million miles (26.7 million km) away – will allow for a re-eneactment of the 1931 event… with the exception that this time amateur skywatchers will also contribute data, instantly, from all over the world!
One has to wonder…when Eros comes this close again in 2056, what sort of technology will we use to watch it then…
Asteroid 433 Eros, seen by NASA's NEAR spacecraft on Feb. 29, 2000. (NASA/JPL/JHUAPL)
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On Tuesday, January 31, asteroid 433 Eros will come closer to Earth than it has in 37 years, traveling across the night sky in the constellations Leo, Sextans and Hydra. At its closest pass of 16.6 million miles (26.7 million km) the relatively bright 21-mile (34-km) -wide asteroid will be visible with even modest backyard telescopes, approaching magnitude 8, possibly even 7. It hasn’t come this close since 1975, and won’t do so again until 2056!
433 Eros is an S-type asteroid, signifying a composition of magnesium silicates and iron. S-types make up about 17 percent of known asteroids and are some of the brightest, with albedos (reflectivity) in the range of 0.10 – 0.22. S-type asteroids are most common in the inner asteroid belt and, as in the case of Eros, can even pass within the orbit of Mars.
Occasionally Eros’ orbit brings it close enough to Earth that it can be spotted with amateur telescopes. 2012 will be one of those times.
Eros was discovered on August 13, 1898, by astronomers Carl Gustav Witt in Berlin and Auguste Charlois in Nice. When Eros’ orbit was calculated it was seen to be an elongated oval that brought it within the orbit of Mars. This allowed for good observations of the bright asteroid, and eventually led to more accurate estimates of the distance from Earth to the Sun.
In February 2000 NASA’s NEAR Shoemaker spacecraft approached Eros, established orbit and made a soft landing on its surface, the first mission ever to do so. While in orbit NEAR took over 160,000 images of Eros’ surface, identifying over 100,000 craters, a million house-sized boulders (give or take a few) and helped researchers conclude that the cashew-shaped Eros is a solid object rather than a “rubble pile” held together by gravity.
Studying pristine objects like Eros gives insight into the earliest days of our solar system, and also allows scientists to better understand asteroid compositions… which is invaluable information when deciding how best to avoid any potential future impacts.
Orbit of 433 Eros for Jan. 31, 2012
Although Eros will be making a “close” approach to Earth on Jan. 31/Feb. 1, there is no danger of a collision. It will still remain at a very respectable distance of about 16.6 million miles (26.7 million km), or 0.178 AU. This is over 80 times the distance of the much smaller 2005 YU55, which safely passed within a lunar orbit radius on November 8, 2011.
If you do want to try viewing 433 Eros as it passes, you can find a diagram charting its path from Sky and Telescope here. According to the Sydney Observatory’s website “the coordinates on 31 January (from the BAA 2012 Handbook) are 10 hours 33 minutes 19.0 seconds RA and -4° 48’ 23” declination. On 10 February the RA is 10 hours 20 minutes 27.6 seconds and the declination is -14° 38’ 49 seconds.”
Also there’s an updated chart on Heavens Above showing Eros’ current position.
Eros should remain visible up until Feb. 10.
Thanks to Skyscrapers, Inc., for a report on 433 Eros by Glenn Chaple. Skyscrapers, Inc. is an amateur astronomy society in Rhode Island that operates the Seagrave Observatory, whose centerpiece is a beautiful 8 1/4″ Alvan Clark telescope built in 1878. I saw Halley’s Comet through that telescope in 1986 and have been hooked on astronomy ever since.
A 5-km-wide crater on Vesta displays light and dark material.
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Light and dark material spreads outward from a 5-km-wide crater on Vesta in this image from NASA’s Dawn spacecraft, acquired on October 22, 2011. While craters with differently-toned materials have been previously seen on the asteroid, it is unusual to find one with such a large amount of ejecta of different albedos.
This is a crop of a larger version which was released today on the Dawn website.
This brightness image was taken through the clear filter of Dawn’s framing camera. The distance to the surface of Vesta is 700 kilometers (435 miles) and the image has a resolution of about 70 meters (230 feet) per pixel.
Vesta resides in the main asteroid belt between the orbits of Mars and Jupiter and is thought to be the source of many of the meteorites that fall to Earth. The Dawn spacecraft successfully entered orbit around Vesta on July 16, 2011.
After its investigation of Vesta, Dawn will leave orbit and move on to Ceres. It will become the first spacecraft to orbit two different worlds.
Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
This radar image of asteroid 2005 YU55 was obtained on Nov. 7, 2011. Credit: NASA/JPL/Caltech.
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Look up in a clear night sky. How many moons do you see? Chances are, you’re only going to count to one. Admittedly, if you count any higher and you’re not alone, you may get some funny looks cast in your direction. But even though you may not be able to actually see them, there may very well be more moons out there orbiting our planet.
For the time being, anyway.
Today, Earth has one major moon in orbit around it. (Technically the Earth-Moon system orbits around a common center of gravity, called the barycenter, but that’s splitting hairs for the purpose of this story.) At one time Earth may have had two large moons until the smaller eventually collided into the larger, creating the rugged lump we now call the farside highlands. But, that was 4 billion years ago and again not what’s being referred to here.
Right now, at his moment, Earth may very well have more than the one moon we see in the night sky. Surprise.
Of course, it would be a very small moon. Perhaps no more than a meter across. But a moon nonetheless. And there could even be others – many others – much smaller than that. Little bits of solar system leftovers, orbiting our planet even farther out than the Moon we all know and love, coming and going in short-lived flings with Earth without anyone even knowing.
This is what has been suggested by researcher Mikael Granvik of the University of Helsinki in Finland. He and his colleagues have created computer simulations of asteroids believed to be occupying the inner solar system, and what the chances are that any number of them could be captured into Earth orbit at any given time.
Orbit of 2006 RH120, a confirmed TCO identified in 2006.
The team’s results, posted Dec. 20 in the science journal Icarus, claim it’s very likely that small asteroids would be temporarily captured into orbit (becoming TCOs, or temporarily captured objects) on a regular basis, each spending about nine months in up to three revolutions around Earth before heading off again.
Some objects, though, might hang around even longer… in the team’s simulations one TCO remained in orbit for 900 years.
“There are lots of asteroids in the solar system, so chances for the Earth to capture one at any time is, in a sense, not surprising,” said co-author Jeremie Vauballion, an astronomer at the Paris Observatory.
In fact, the team suspects that there’s most likely a TCO out there right now, perhaps a meter or so wide, orbiting between 5 and 10 times the distance between Earth and the Moon. And there could be a thousand smaller ones as well, up to 10 centimeters wide.
So if these moons are indeed out there, why don’t we know about them?
Put simply, they are too small, too far, and too dark.
At that distance an object the size of a writing desk is virtually undetectable with the instruments we have now.. especially if we don’t even know exactly where to look. But in the future the Large Synoptic Survey Telescope (LSST) may, once completed, be able to spot these tiny satellites with its 3200-megapixel camera.
Once spotted, TCOs could become targets of exploration. After all, they are asteroids that have come to us, which would make investigation all the easier – not to mention cheaper – much more so than traveling to and back from the main asteroid belt.
“The price of the mission would actually be pretty small,” Granvik said. And that, of course, makes the chances of such a mission getting approved all the better.
Read more on David Shiga’s article on New Scientist here.
Passage of of 2005 YU55 near Altair from 6:03 p.m. – 6:12 p.m. EST (11:03 – 11:12 UTC)
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It’s already been stated several times here on Universe Today that 2005 YU55, a 400-meter-wide roughly spherical asteroid, will not pose any threat to Earth as it passes by on Tuesday, November 8… even though it will come within 80% of the distance to the Moon. Many experts have come forward to state this fact, including Don Yeomans of JPL’s Near-Earth Object Observation Program and Lance Benner, a radio astronomer with the Deep Space Network in Goldstone, CA. But it will still be a notable event, being the first time since 1976 such a large object will pass so closely by our planet. So, with the eve of YU55’s approach upon us, let’s turn our curiosity toward another aspect of this cosmic visitation: how can we see it?
Unfortunately there are a couple of factors working against the casual observer being able to witness YU55’s pass. One: it’s a dark object. A very dark object. 2005 YU55 is a C-type asteroid, which means it is composed of carbonaceous material and is thus effectively darker than coal, reflecting less than 1% of the sunlight that it receives. It probably won’t be brighter than magnitude 10. (On the backwards-ranked scale of apparent magnitude, 6 is the limit of best visibility to the average human eye, while -1 or 0 would be a very bright star. Jupiter is about -3 right now, while the full moon would be -12.7. In a typical suburban neighborhood 3 or 4 is the limit of naked-eye visibility.)
And two: the Moon will be close to full on the night of the 8th, and YU55 will be headed in its direction. That sure won’t help visibility.
But, should you be located in a dark area, and should you have a 6″ or larger telescope at your disposal, you may want to give a go at spotting the asteroid that’s caused quite a fuss over the past few months for yourself. It won’t be a simple task, but it’s not impossible – and to help you out teacher, writer and astronomy enthusiast David Dickinson has posted an article about it on his blog, Astro Guyz.
Here’s an exerpt:
Closest approach to Earth occurs at 11:29 UTC/06:29 EST at about 202,000 miles distant, placing it high to the southwest for observers on the US Eastern Seaboard. At its closest approach, 2005 YU55 will glide along at one degree every 7 minutes, easily noticeable after a few minutes of observation at low power. I plan to target selected areas with my GOTO mount, sketch the field, then watch for changes. I may also take some wide-field piggyback stills with the DSLR, but mostly, this one will just be fun to watch.
Visually tracking a Near-Earth asteroid can be thrilling to watch; for example, I’ve actually seen 4179 Toutatis years ago show discernable movement after tracking it for a few moments in the eyepiece!
– David Dickinson
Wide field finder of 2005 YU55 from sunset until 8:30PM EST.
The asteroid will pass through the constellations Aquila, Delphinus, and Pegasus as it heads westward. Interestingly, 2005 YU55 passes within a degree of Altair centered on 6:07:30PM EST only 27 minutes after local sunset, and also makes a very close pass of the star Epsilon Delphini during closest approach. These both make good visual “anchors” to aim your scope at during the appointed time and watch. Keep in mind, the charts provided are rough and “Tampa Bay-centric…”
On an approach as close as this one, two factors muddle the precise prediction coordinates of the asteroid; one is the fact the gravitational field of the Earth will change the orbit of 2005 YU55 slightly, and two is that the position will change due to the position of the observer on the Earth and the effect of parallactic shift. Many prediction programs assume the Earthly vantage as a mere point in space, fine for positioning deep sky objects but not so hot for ones passing near the planet. A good place to get updated coordinates is JPL Horizons website which lets you generate an accurate ephemeris for your exact longitude latitude and elevation.
David goes on to add:
2005 YU55 will pass our Moon at 8 AM Universal Time on November 9th at a distance only marginally closer than it did the Earth, at 140,000 miles. Interestingly, it also transited Sun on November 3rd as seen from the Moon, but would have appeared <1” in size, a tough target for any would-be lunar-based observer. Its next close predicted passage of the Earth won’t be until 2056 at nearly 3 times the distance.
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Excellent information… many thanks to David for sharing with us! (You can read the full article on his website here.) And if you do witness the pass of this asteroid and somehow manage to get some photos of it, you can share them on the Universe Today Flickr group… they may be featured in an upcoming article!
A radar image an asteroid, 2005 YU55, acquired in April 2010. (This is not the asteroid that will pass by Earth on Jan. 27, 2012)Credit: NASA
NASA’s Jet Propulsion Laboratory released this video today featuring more information about the much-discussed 2005 YU55, a 400-meter-wide asteroid that will pass by Earth next Tuesday at a distance closer than the Moon. The video features research scientist Lance Benner, an expert in radio imaging of near-Earth objects.
While YU55 will come closer than any object we’ve been aware of in the past 35 years, it poses no risk to Earth.
“2005 YU55 cannot hit Earth, at least over the interval that we can compute the motion reliably, which extends for several hundred years.”
– Lance Benner, JPL Research Scientist
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While we can’t state enough that there’s no danger from YU55, this close pass will offer a fantastic opportunity for scientists to acquire detailed radar images of this ancient C-type asteroid.
NASA’s Near-Earth Objects Observation Program will continue tracking YU55 using the 70-meter radar telescope at the Deep Space Network in Goldstone, California, as well as with the Arecibo Planetary Radar Facility in Puerto Rico.
“This is the closest approach by an asteroid this large that we’ve known about in advance,” said Benner. “The Goldstone telescope has a new radar imaging capability which has just become available that will enable us to see much finer detail than has previously been possible.”
Radar imaging allows scientists to better study the surface features and composition of fast-moving, dark objects like YU55 which reflect very little visible light.
Space.com has provided a great infographic that shows exactly where this asteroid will pass by Earth. Note that the side view plainly shows that the path of the asteroid is well above the plane of the Earth/Moon orbit.
A radar image an asteroid, 2005 YU55, acquired in April 2010. (This is not the asteroid that will pass by Earth on Jan. 27, 2012)Credit: NASA
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Yes, it’s coming. Yes, it’s big. Yes, it will be even closer than the Moon. And yes… we’re completely safe.
The 400-meter-wide asteroid 2005 YU55 is currently zipping through the inner Solar System at over 13 km (8 miles) a second. On Tuesday, November 8, at 6:28 p.m. EST, it will pass Earth, coming within 325,000 km (202,000 miles). This is indeed within the Moon’s orbit (although YU55’s trajectory puts it a bit above the exact plane of the Earth-Moon alignment.) Still, it is the closest pass by such a large object since 1976… yet, NASA scientists aren’t concerned. Why?
Because its orbit has been well studied, there’s nothing in its way, and frankly there’s simply nothing it will do to affect Earth.
Animation of 2005 YU55's trajectory on Nov. 8. (NASA/JPL) Click to play.
Period.
2005 YU55’s miniscule gravity will not cause earthquakes. It has no magnetic field. It will not strike another object, or the Moon, or the Earth. It will not come into contact with cometary debris, Elenin, a black dwarf, Planet X, or Nibiru. (Not that those last three even exist.) No, YU55 will do exactly what it’s doing right now: passing through the Solar System. It will come, it will go, and hopefully NASA scientists – as well as many amateur astronomers worldwide – will have a chance to get a good look at it as it passes.
Scientists with NASA’s Near-Earth Objects Observation Program will begin tracking YU55 on Friday, November 4 using the 70-meter radar telescope at the Deep Space Network in Goldstone, California , as well as with the Arecibo Planetary Radar Facility in Puerto Rico beginning November 8. These facilities will continue to track it until the 10th.
This close pass will offer a great opportunity to get detailed radar imaging of YU55, an ancient C-type asteroid literally darker than coal. Since these objects can be difficult to observe using visible light, radar mapping can better reveal details about their surface and composition.
To help inform the public about YU55 NASA’s Jet Propulsion Laboratory in Pasadena recently hosted a live Q&A session on Ustream featuring specialists Marina Brozovic, a Goldstone Radar Team scientist, and Don Yeomans, manager of NASA’s Near-Earth Object Program. They fielded questions sent in via chat and Twitter… a recording of the event in its entirety can be seen below:
Undoubtedly there will still be those who continue to spread misinformation about 2005 YU55. After all, they did the same with the now-disintegrated comet Elenin. But the truth is out there… and the truth is that there’s no danger, no cover-ups, no “plots”, and simply no cause for concern.
UPDATE: JPL has released a brief video about YU55 featuring research scientist Lance Benner, who specializes in radar imaging of near-Earth objects:
Although classified as a potentially hazardous object, 2005 YU55 poses no threat of an Earth collision over at least the next 100 years. However, this will be the closest approach to date by an object this large that we know about in advance and an event of this type will not happen again until 2028 when asteroid (153814) 2001 WN5 will pass to within 0.6 lunar distances. – Near-Earth Object Program, JPL
Radar image of asteroid 2005 YU55, acquired in April 2010. Credit: NASA/Cornell/Arecibo.
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On Tuesday, November 8, at 6:28 p.m. EST, an asteroid the size of an aircraft carrier will soar past our planet at a distance closer than the Moon… and NASA scientists will be watching!
2005 YU55, a 400-meter (1,300-foot) -wide C-type asteroid, was discovered in December 2005 by Robert McMillan of the Spacewatch Program at the University of Arizona, Tucson. It’s pretty much spherical in shape and dark – darker than charcoal, in fact! Scientists with NASA’s Near-Earth Objects Observation Program will begin tracking it on November 4 using the 70-meter radar telescope at the Deep Space Network in Goldstone, California , as well as with the Arecibo Planetary Radar Facility in Puerto Rico beginning November 8. They will continue tracking 2005 YU55 through November 10.
Animation of 2005 YU55's trajectory on Nov. 8. (NASA/JPL) Click to play.
YU55’s orbit is well understood by scientists. It has come this way before, and although this is the closest it’s come to Earth in at least two centuries it will still be at least 324,600 kilometers (201,700 miles) away at nearest approach. That’s about 85% of the distance to the Moon.
It will approach from the sunward side, making viewing in visible light difficult until after it’s made its closest pass.
Other than the excitement it will most likely cause amongst radar astronomers, 2005 YU55 will have no physical effect on our planet. (There have been some rumors circulating online about this particular asteroid’s upcoming pass, in regards to earthquakes and tidal fluctuations and atmospheric disturbances and other such nonsense… the bottom line is that, like the ill-fated comet Elenin, 2005 YU55 has never been known to pose any threat to Earth.)
“YU55 poses no threat of an Earth collision over, at the very least, the next 100 years,” said Don Yeomans, manager of NASA’s Near-Earth Object Program Office at JPL. “During its closest approach, its gravitational effect on the Earth will be so miniscule as to be immeasurable. It will not affect the tides or anything else.”
The 70m telescope at the Goldstone Deep Space Communications Complex in California's Mojave Desert. (NASA/JPL)
Scientists are very eager though to have a prime opportunity to study this quarter-mile-wide world as it makes its closest pass. The giant telescopes at Goldstone and Arecibo will bounce radar waves off the asteroid, mapping its size and shape, and hopefully obtain some very high-resolution images.
“Using the Goldstone radar operating with the software and hardware upgrades, the resulting images of YU55 could come in with resolution as fine as 4 meters per pixel. We’re talking about getting down to the kind of surface detail you dream of when you have a spacecraft fly by one of these targets.”
– Lance Benner, JPL radio astronomer
Even though YU55 will remain at a safe distance the event is still quite notable. The last time an object this large came so close to Earth was in 1976… and scientists weren’t even aware of it at the time. Luckily we now have programs like the Near-Earth Objects Observations Program – a.k.a. “Spaceguard” – to identify asteroids like this, hopefully in time to know if they could become a danger to our planet in either the near or distant future.
As of now, no large space rock with Earth’s name on it has been positively identified… but that doesn’t mean there’s nothing out there either. We need to keep diligent, keep looking and, above all, keep funding programs like this. If anything, this pass should serve as a reminder – however harmless – that we certainly are not alone in the solar system!
Asteroid or rocket booster? 2010 AL30 as imaged remotely from Australia on Jan. 11, 2010. Credit: Ernesto Guido & Giovanni Sostero
[/caption] Caption: Asteroid or rocket booster? 2010 AL30 as imaged remotely from Australia on Jan. 11, 2010. Credit: Ernesto Guido & Giovanni Sostero, Remanzacco Observatory.
An unusual object will make a close flyby of Earth on Wednesday, coming within only 128,000 km (about 80,000 miles), or at a distance about three times less than the moon’s orbit. The object, named 2010 AL30, is about 10-15 meters long, and asteroid watchers say there is no chance it will hit the planet. But is it an asteroid or perhaps a piece of space junk, like a spent rocket booster?
UPDATE: The Solar System Dynamics website now says the object is an Apollo-type asteroid, which are Near-Earth asteroids that have orbits which cross the Earth’s orbit and pass approximately 1 AU or less from Earth.
According to Italian astronomers Ernesto Guido and Giovanni Sostero of the Remanzacco Observatory, who took this image (above) of 2010 AL30, it has an orbital period of almost exactly one year and might be a man-made object.
However, Alan Harris, senior researcher at the Space Science Institute said the object has a perfectly ordinary Earth-crossing orbit.
“Unlikely to be artificial, its orbit doesn’t resemble any useful spacecraft trajectory, and its encounter velocity with Earth is not unusually low,” he said.
Several observatories, including the Goldstone Radar will be observing NEO 2010 AL30 during its Earth flyby. After the January 13 close flyby, it will go too close to the Sun to be observed.
