Forbidding Planet: Scientists find remains of monster asteroid impacts on early Earth

Artist’s view of Earth several billion years ago during the Late Heavy Bombardment, when the planet is thought to have been battered by impacts of comets and asteroids. Credit: Chris Butler/SPL

Earth 3.5 billion years ago was a terrifying place. Picture a rocky landscape pounded by meteorites and asteroids with a surface resembling that of the moon. Volcanoes spewed water vapor but also a toxic mix of carbon dioxide, sulfur dioxide and methane. If you could whisk yourself back to this world by time machine, you’d need to be fully protected by a spacesuit and lucky enough to not get picked off by a falling space rock. Oh, and bring a boat too. Hot-water oceans likely covered a fair portion of the planet back then.

This time-lapse illustration of the Nice (pronounced ‘neece’) model of solar system evolution shows how outer planet migrations kick asteroids into the inner solar system

Scientists call the period from about 3.8 billion to 1.8 billion years ago the Late Heavy Bombardment (LHB), a time when the number of asteroids and their fragments pelting the inner planets and their moons spiked. Why then? No one’s absolutely certain, but the leading theory posits that the migration of the giant outer planets to their present positions “stirred the gravitational pot”, slinging boatloads of asteroids into the inner solar system, where they rained down on Earth and its neighbors in hellish monotony for millions of years.

Anyone with a small telescope can see resulting devastation to this day. Just take a long look at the moon’s battered and cratered surface and thank your lucky stars you’re around during a more peaceful time. Finding Earth’s craters is trickier because water and wind erosion, along with the continual recycling of much of our planet’s crust through plate tectonics, has erased much of our violent past.

The Vredefort Dome – these concentric hills, which rebounded after the impact that created Vredefort Crater – are what remains after an asteroid about 3-6 miles wide struck Earth 2 billion years ago. Credit: NASA

About 180 craters are known on Earth today, but we’re aware of only three resulting from the Late Heavy Bombardment. The oldest, estimated at 3 billion years old and 62 miles (100 km) wide, is also the most recently discovered. Found in western Greenland in 2012, all that remains of the impact are rocks rattled by the massive shock wave that penetrated 15 miles (25 km) deep within Earth’s crust.

You can still see the remains of the impacts that formed the 112-mile-wide (180 km) Vredefort Crater in South Africa, which is 2 billion years old, and the youngest LHB member, the 155-mile (250-km) Sudbury crater in Canada dated at 1.85 billion years.

Map of South Africa with the Barberton greenstone belt shown in red. Shock waves from the impact of an asteroid 3.26 billion years ago created telltale formations within the belt. No one knows yet where the impact happened.

Now, a group of scientists have announced they’ve found evidence for an even older impact, one that occurred 3.26 billion years ago and left its signature in a South African region known as the Barberton greenstone belt.

A recent press release describes the huge impactor as between 23 and 36 miles wide (37- 58 km). Colliding with the planet at 12 miles per second, the jolt delivered was bigger than a 10.8 magnitude earthquake and propelled seismic waves hundreds of miles through the Earth, breaking rocks and setting off other large earthquakes. Tsunamis thousands of feet deep swept across the oceans that covered most of the planet at that time.

A graphical representation of the size of the asteroid thought to have killed the dinosaurs (left), and the crater it created, compared to an asteroid thought to have hit the Earth 3.26 billion years ago and the size of the crater it may have generated. A new study reveals the power and scale of the event some 3.26 billion years ago which scientists think created geological features found in a South African region known as the Barberton greenstone belt. Credit: American Geophysical Union

“We knew it was big, but we didn’t know how big,” Donald Lowe, a geologist at Stanford University and a co-author of the study, said of the asteroid.

The collision would have blasted out a crater some 300 miles (500 km) wide, filled the atmosphere with fiery rock vapor and set the surface of the ocean a-boil. We’re talking serious cataclysm. Somehow life found a way through the heat and crater-punching to gift us with the rolling green hills, coral reefs and forests that characterize Earth today.

Table from the book “Near Earth Objects – Finding Them Before They Find Us” by Donald Yeomans showing average asteroid impact results and probabilities by size. Credit: Donald Yeomans

I try to imagine the dark days of the LHB to help me appreciate these calmer times. Yet we know in our gut – and in fact, thanks to probability – that we’ll never truly be out of the woods. Asteroids lurk in the deep that could one day cause a similar scenario. Don’t let it worry you too much – the chance of a 10-mile-wide space rock striking Earth is once every 89 million years. You’ve still got time to take a nap, catch a show and enjoy a few nights out on the town. Probably.

Surprise! Astronomers discover rings around an asteroid

Artist’s impression shows how the rings might look from close to the surface of asteroid 10199 Chariklo which orbits between Saturn and Uranus. The two dense, narrow rings were discovered by surprise last June. Click to enlarge. Credit: ESO/L. Calcada/Nick Risinger

Ever heard of the asteroid Chariklo (KAR-ik-lo)? I didn’t either until today, but this obscure object will now enter the textbooks as the first asteroid ever discovered with rings. That’s right – rings. Like Saturn, Jupiter, Uranus and Neptune. That makes this new ringbearer only the 5th body known to possess this feature and the smallest by far at only 155 miles wide.

Another artist’s impression of Chariklo and its pair of skinny rings as it might look from an orbiting space probe. The rings are just 240 miles above its surface. The asteroid orbits between Saturn and Uranus and might be made of mostly ice like a comet. Credit: ESO/L. Calcada/Nick Risinger

Two dense, sharply confined rings just 4.3 and 1.8 miles wide separated by a gap of 5.6 miles orbit this remote Centaur asteroid. How they got there is anyone’s guess, but they’re likely debris from a long-ago collision with another asteroid or comet. Scientists believe their distinctive shapes and crisp edges are shaped and herded by the gravitational influence of a tiny, yet to be discovered “sheparding” moon embedded within the ring plane. Sheparding moons are responsible for many of the narrow gaps and crisp record-groove-like ringlets around Saturn.

Saturn’s moons Pandora (left) and Prometheus confine the planet’s F-ring and create curious warps and waves within it. Something similiar may help define Chariklo’s two rings. Credit: NASA/JPL/Space Science Institute

The discovery was serendipitous. Astronomers using seven telescopes across southern South America watched Chariklo pass in front of or occult a star. To their surprise, the star’s light dipped in brightness both a few seconds before and few seconds after the main occultation. Something around the asteroid was blocking the light. By comparing observations from all seven sites, they learned not only the shape and size of the asteroid, but also the shape, widths and orientation of the rings.

“We weren’t looking for a ring and didn’t think small bodies like Chariklo had them at all, so the discovery — and the amazing amount of detail we saw in the system — came as a complete surprise!” said Felipe Braga-Ribas of the Observatório Nacional/MCTI in Brazil, who planned the observation campaign and is lead author on the new paper.

This artist’s impression shows the view from inside the ring system, with Chariklo behind and a putative shepherding satellites also visible. The leaders of this project are provisionally calling the rings by the nicknames Oiapoque and Chuí, two rivers near the northern and southern extremes of Brazil. Credit: ESO/L. Calcada/Nick Risinger

Chariklo belongs to a class of asteroids called Centaurs that orbit between Jupiter and Neptune and cross the orbit of one or more giant planets as they circle the sun. They’re believed to have originated in the outer asteroid belt beyond Neptune called the Kuiper Belt and perturbed by Neptune’s gravity to their present location.

Because Centaurs’ orbits cross those of the giant planets their days are numbered. If they don’t eventually collide with a giant planet, they’ll be flung by its gravity straight out of the solar system. Centaurs have lifetimes measured only in millions of years – that’s why it’s thought they’re continually replenished by Neptune’s massaging of the the inner Kuiper Belt.

Size comparison of Chariklo, Pluto and the moon. Credit: Wikipedia

Some Centaurs mimic comets, developing hazy comas of gas and dust, but all we so far of Chariklo’s composition is that it shows signs of amorphous carbon and possibly water ice.

Astronomers made the ring system discovery in June 2013 when Chariklo – and its rings – passed in front of a faint star, briefly blocking its light. Credit: ESO

It was discovered in 1997 and is the largest known Centaur, orbiting the sun every 63 years. The rings are dense and orbit just 240 miles above the asteroid’s surface. What a sight they’d be slicing across the starry sky!

Asteroid Erigone makes a bright star vanish for 14 seconds – Don’t miss this rare event!

Illustration showing asteroid 163 Erigone about to cover Leo’s brightest star Regulus around 2:07 Eastern Daylight Time Thursday morning March 20, 2014. As the asteroid’s shadow passes over the ground, observers will see Regulus disappear for up to 14 seconds. Illustration: Bob King with help from photos by the ESO/NASA

How does a tiny asteroid make one of the brightest stars in the sky disappear? By passing directly in front of it. Upwards of 20 million people will have the opportunity to watch asteroid 163 Erigone occult the bright star Regulus for up to 14 seconds next Thursday morning March 20. Billed as the best and brightest occultation ever predicted for North America, the sight of Regulus vanishing in plain sight should be a jaw-dropper.

Predicted path of the asteroid shadow. Shortly after 2:06 am EDT on March 20 observers between the red lines have the best chance of seeing the bright star Regulus temporarily disappear as asteroid 163 Erigone passes in front of it. Times shown are EDT. Click for detailed map. Credit: IOTA

Only thing is, you just have to be in the right place to see it. Check the map. If you live within the band, which cuts a swath some 45 miles (73 km) wide from northern Ontario to New Jersey, you’re in! While the northern reaches of the occultation occur over sparely populated tundra, the southern half encompasses all of New York City plus a few nibbles of New Jersey and Connecticut. All the rest of us will have to travel to the centerline much as we would to see a total eclipse of the sun.

To find Regulus, face southwest shortly before 2 a.m. The star will be about 40 degrees high (four ‘fists’ held at arm’s length against the sky). Brilliant Jupiter shines well to its lower right. You may also notice a ‘coathangar’ or ‘backwards question mark’ shape of stars above Regulus called the Sickle of Leo. Stellarium

It’s hard to imagine Regulus casting rays of starlight on Earth, but it really does just as all the stars do. During the occultation, Erigone (eh-RIG-uh-nee), a smallish asteroid about 45 miles (73 km) across, will block the star’s light, casting a shadow for up to 14 seconds for those situated along the centerline. The farther from the centerline, the less time Regulus will vanish from view. If you live just outside the error limits (shown in red on the map) you’ll miss the shadow (and occultation) entirely.

We don’t know a whole lot about Erigone. It was discovered in 1876 by French astronomer Henri Joseph Perrotin and based upon its spectrum (what “colors” of light it absorbs and reflects), it’s classed as a C-type asteroid rich in water-containing minerals. Like the largest asteroid Ceres, it resembles meteorites that fall to Earth called carbonaceous chondrites. At 45 miles in diameter and dark as a charcoal briquette, that’s about it. During the occultation it will shine at magnitude 12.4 and remain hidden in the glare of Regulus.

But here’s where amateur and even beginning astronomers can help. If lots of observers across many locations make accurate timings of the disappearance and reappearance of Regulus, we can construct an outline of the asteroid’s shape with a resolution of 0.6 miles (1 km) at its distance of 110 million miles (177 million km). That’s incredible.

On July 19, 2011, amateur astronomers discovered through multiple timings – each observer represented by a color line –  that asteroid 90 Antiope was not a single object but two co-orbiting asteroids! We might be in for similar surprises with Erigone. Notice that the “yellow line” observer recorded only a brief disappearance of the background star; the green line observer saw a much longer occultation since the full width of Antiope blocked the star. Credit: IOTA

For one observer, only the tip of Erigone will pass in front of Regulus, causing the star to blink off and on again very quickly. Another may see the full bulk of the asteroid block the star for many seconds. Plotting all these chords of visibility on a graph will yield a clear profile of Erigone’s silhouette as well as refine its orbit with great precision.

Dedicated occultation watchers have been doing this for years with mostly fainter stars, sometimes traveling great distances to secure a key data point. They use video cameras with a GPS video time inserter to make timings accurate to 1/10 of a second or better and contribute their results to the International Occultation Timing Association or IOTA.

Click to see the video on how to use the free iPhone occultation app to time the disappearance and reappearance of Regulus.

Many in the organization will be out there at 2 a.m. Thursday March 20, and you can too. If you’d like to make and submit your observation, it’s super easy. Just download the free iPhone app Occultation 1.0 and tap the screen when Regulus winks out and again when it reappears. For instructions on how to use it, check out the video. A similar free app called Time the Sat is available for Android devices.

A potential unknown moon of Erigone might be found by timing Regulus’ disappearance and reappearance well outside the central swath between the two gray bands. Credit: IOTA/Ted Blank/Google Earth

By the way, “misses” are as important as “hits” when it comes to occultations. Misses help define the edges of the asteroid. You can’t determine a true shape unless you know where Erigone ends and empty space begins. Other discoveries could also be made. Anyone living from northern Minnesota to Kentucky to Nova Scotia could conceivably see a brief disappearance from an unknown moon of the asteroid.

Regulus has an end-to-end diameter of 4.3 times the size of the sun due to its rapid rotation. Because of its large size, it won’t blink out instantaneously. Observers making very careful timings may be able to “see” the shape of the star. Illustration: Bob King

Even Regulus gets into the act. It’s a hot, blue star 79 light years from Earth and spinning so rapidly (once every 16 hours compared to the sun’s leisurely once every 27 days) that it’s stretched into an ellipse.

Multiple precise timings by careful observers could very well refine the shape of the star. How often do we get that kind of opportunity? Awesome in the extreme!

Not that you have to “do science” during the event, though I highly recommend it. Of course there’s also nothing wrong with simply enjoying one of the rarest sights you’ll ever see.

For complete information on everything from weather to software, do stop by IOTA’s Regulus occultation site. It’s loaded with good stuff. Click HERE for a detailed Google Earth Map with path.

Touched by the sun, oddball asteroid crumbles before our very eyes

he NASA/ESA Hubble Space Telescope photographed the break-up of P/2013 R3 from Oct. 29, 2013 to Jan. 14, 2014. Although fragile comet nuclei have been seen to fall apart as they approach the Sun, nothing like this breakup, which occurred in the asteroid belt, has ever been observed before. Click to enlarge. Credit: NASA/ESA/D. Jewitt (UCLA)

The Hubble Space Telescope has photographed a never-seen-before breakup of an asteroid. Named P/2013 R3 (Catalina-PanSTARRS), it was discovered last September 15 by the Catalina and Pan-STARRS sky surveys as a faint, slightly fuzzy object. Two weeks later, the giant Keck Telescope in Hawaii took a closer look and saw not one but three separate pieces cruising along convoy-style in a dust cloud of their own making.

Animation showing the break up of P/2013 R3

By December it had crumbled into ten pieces, the four largest of which measure about 650 feet (200 meters) across or nearly two football fields apiece. The Hubble data show the fragments are drifting apart at the leisurely rate of just under 1 mile per hour (1.5 km/hr) or about the speed of someone walking while texting.

“This is a really bizarre thing to observe — we’ve never seen anything like it before,” says co-author Jessica Agarwal of the Max Planck Institute for Solar System Research, Germany. ”The break-up could have many different causes, but the Hubble observations are detailed enough that we can actually pinpoint the process responsible.”

P/2013 R3 on Oct. 22, 2013 looked very much like a comet. The individual pieces that comprise the shattered asteroid are too small to resolve in this photo. The fresh dust exposed as the asteroid fell apart shows as a faint tail. Credit: Damian Peach

Astronomers have ruled out a collision, which would have happened suddenly and sent pieces flying apart at much great speeds. Shattering from the pressure of vaporizing ices in its interior also seems unlikely given the asteroid’s distance of 298 million miles (480 million km) from the sun –  believed too cold for any ice it might possess to suddenly turn to vapor and pry the body apart. Besides, if it did contain ice, P/2013 R3 wouldn’t be considered an asteroid anymore but a main belt comet, an asteroid-like object between Mars and Jupiter that occasionally flares up as a comet.

So what could be responsible for perpetrating killing off an asteroid? Scientists suspect it was YORP up to his old tricks. YORP or the Yarkovsky-O‘Keefe-Radzievskii-Paddack effect requires only the light touch of sunshine to get rolling.

This illustration shows one possible explanation for the disintegration of asteroid P/2013 R3. Sunlight absorbed unequally across the asteroid’s surface can spin up its rotation and cause it to fall apart. More details on how this happens below. Credit: NASA, ESA, D. Jewitt (UCLA), and A. Feild (STScI)

Sunlight absorbed by P/2013 R3 is re-emitted as heat. Assuming the asteroid is irregular in shape – and most are because they’re so small – some areas get hotter and give off more heat than others. The imbalance causes a torque on the asteroid, increasing its spin rate.

Hubble Space Telescope close up of P/2013 R3 breaking up as seen on Nov. 15, 2013. Although fragile comet nuclei have been observed to fall apart as they approach the sun, this is the first time an asteroid has been seen to do so. Click to enlarge. Credit: NASA/ESA/D. Jewitt (UCLA)

Many asteroids are “rubble piles” of individual objects held together by gravity rather than solid rocks. Collisions with other asteroids over the 4.5 billion year lifetime of the solar system have shattered and pulverized their interiors. Primed to fall apart, the spin-up from YORP causes the asteroid to come apart at the seams. Pieces that were loosely-bound can drift away due to centrifugal forces; fresh dust exposed creates an enveloping comet-like cloud of debris. Pretty darn cool.

Yorping the day away. Illustration showing how sunlight absorbed unevenly by an asteroid’s surface creates torque that can increase its spin rate. Illustration: Bob King

We’ve seen one other instance of an asteroid breaking to pieces when Hubble photographed the aftermath of a head-on collision between the peculiar comet-like asteroid P/2010 A2 and a smaller asteroid in January 2010. But this is the first time ever we’ve watched an asteroid fall apart of its own accord.

“This indicates that the Sun may play a large role in disintegrating these small Solar System bodies, by putting pressure on them via sunlight,” said Agarwal.

Much of P/2013′s debris, weighing in at around 200,000 tons, will spiral its way into into the sun, but a portion could one day light up Earth’s skies as a lovely meteor shower. Amazing isn’t it how nature shares its incredible stories when we pay attention.

Even tinier asteroid 2014 EC flies just 48,000 miles from Earth tomorrow

This is where 2014 EC is today as it heads towards its close Earth flyby tomorrow. Credit: NASA/JPL

Don’t forget to look both ways. You can hardly cross the street but another asteroid comes flying by. Last night astronomers discovered a new object named 2014 EC. This one’s tiny – only 33 feet (10 meters) across or about half the size of the asteroid that blasted to bits over Chelyabinsk, Russia last February.

It zooms by Earth tomorrow March 6 around 3 p.m. CST at a distance of just 48,000 miles (77,000 km). Again, there’s no threat of a strike. Asteroids can pass very close to the planet without getting “sucked in” by gravity because they’re moving forward in their orbits at tens of thousands of miles an hour. That’s a lot of momentum.

Still, a small asteroid making a pass near Earth doesn’t get away scot-free. Much like the Voyager space probe (and others) that passed close to one planet to slingshot to the next, small asteroids passing near Earth have their orbits re-shaped by our planet’s gravity and sent on their way on a different trajectory.

Three classes of asteroids that pass near Earth or cross its orbit are named for the first member discovered — Apollo, Aten and Amor. Apollo asteroids like 2014 EX110 routinely cross Earth’s orbit, Atens briefly cross and Amors cross Mars’ orbit but miss Earth’s. Credit: ESA

As 2014 EC is another Earth-approaching asteroid like 2014 EX110, there’s always a possibility it could smack out planet in the future. And I do mean future. At the moment, there’s a one in 2.7 million chance of an impact in 2025. Once more observations are in and the orbit refined, those chances will likely be even less.

Amateur astronomers living in Europe, the Middle East and Africa will be able to spot this little rock shining dimly at around magnitude 13.5-14.0 for a couple of hours centered on closest approach as its tears across the constellations Hydra, Antlia and Vela. You’ll need at least an 8-inch telescope to spot it. Click HERE to get positions to make a map of its travels.

For those of us without giant telescopes or living where it daytime during the close passage, the Virtual Telescope Project will feature a live webcast of 2014 EC’s flyby. Tune in around 1:30 p.m. CST. If that link isn’t working, please check SLOOH’s live-cast HERE.

Asteroid 2014 DX110 shoots by Earth today, misses planet by 216,000 miles

Asteroid 2014 DX110 orbits in nearly the same plane as Earth’s orbit and will be passing 0.9 lunar distances (216,00 miles) from us around 3 p.m. today. Credit: Virtual Telescope Project

The space rocks just keep a comin’. This time, newly discovered 2014 DX110 will pass just 216,000 miles from the Earth today around 3 p.m. CST. Break out those stopwatches – this 98-foot-wide bugger will be speeding by at 32,076 mph.

Bear in mind that close flybys of Earth are fairly routine with an average of one or two asteroids a month passing within the moon’s distance of our planet. 2014 DX 110 is no exception and poses no harm to Earth. What makes the flyby of interest is the very thing that makes it so routine. We now see so many of these lively asteroidal sprites thanks to better equipment and multiple sky surveys. This one was captured by the Pan-STARRS1 survey from Maui, Hawaii  on Feb. 28.

You can also watch the flyby on live webcast with commentary courtesy of the fine folks at the Virtual Telescope Project. The show starts at 3:30 p.m. CST (4:30 Eastern, 1:30 Pacific). If you miss it, the group plans another live Webcast when 2014 CU13 zips by on March 10. While that asteroid’s larger at 590 feet (180 meters), it will be considerably farther at 1.86 million miles.

Illustration showing asteroids orbiting the sun. Apollo asteroids like 2014 DX110 have orbits that take them from inside the asteroid belt at farthest to approximately Earth’s distance from the sun when closest. Credit: NASA/ JPL-Caltech

2014 DX110 belongs to the same class of near-Earth asteroids from whence came the mighty meteorite that exploded over Russia last February 15. These Earth-crossings bodies are named for asteroid 1862 Apollo, discovered in 1932. Apollos have orbits that take them very near the Earth with the potential for a future collision.

Don’t worry too much about DX110. According to NASA’s Earth Impact Risk Summary site, it has a 1 in 10,000,00 chance of hitting the planet on March 4, 2046. But since this estimate is based only on 28 observations spanning just under 4 days, future observations will probably lessen that barely significant probability even more.

Too bad a close approach won’t mean a bright point of light. The asteroid isn’t expected to get any brighter than magnitude 15, putting it well beyond the reach of beginners and even many amateurs. Why? It’s just too small. You’ll need at a 12.5-inch telescope and a darn good map to track it, since DX110 will be dashing across the sky.

Most likely you’ll be pouring another cup of coffee or trying not to yawn too loudly at a meeting when 2014 DX110 goes whizzing by later today. Or maybe you’ll get fired up and dial up a live view at the link above. Know this. Despite over 4.5 billion years of time to clean up its act, the solar system still has enough leftover rocks and snowballs to rattle the nerves. Just a little.

UPDATE March 5: Another just-discovered asteroid, 2014 EC, will pass considerably closer to Earth tomorrow at 3 p.m. – hey, how about that, same as today’s flyby. Predictions call for it to miss us by 48,000 miles. Again, there’s no threat of a strike. Asteroids can pass very close to the planet without concern about being “sucked in” by gravity because they’re moving forward in their orbits far too fast. The Virtual Telescope Project will also be featuring a live webcast of 2014 EC’s flyby.

(Note: The webcast link for 2014 EC is correct but I’ve noticed it doesn’t connect on occasion. I’ll update again if the link changes. You can also check out SLOOH’s live-cast HERE.)

Asteroid underdog Pallas bright and close this month – Here’s how to see it

Pictures of Pallas (right) taken by the Hubble Space Telescope and a model of its surface. The darker, circled area may be a large impact crater. Pallas is named for Pallas Athena, an alternate name for the Greek goddess Athena of wisdom and courage. Credit: NASA / JPL

Being number two isn’t all that bad. Less pressure than the number one spot and yet you still have a foot in the limelight. Asteroid 2 Pallas was the second asteroid discovered back in the days when asteroids were so few and novel they were called planets. German astronomer Heinrich Olbers accidentally ran across it while attempting to find another asteroid, Ceres, on March 28, 1802.

This week you can see Pallas at its brightest in two decades as it treks from Sextans into Hydra the Water Snake during convenient evening viewing hours. With the asteroid shining at around magnitude 7 – just one level fainter than naked eye visibility – all you need is a pair of binoculars, a map and a clear night.

The path of asteroid 2 Pallas as it slides along the back of the water snake constellation Hydra. It will appear as a star in telescopes and binoculars moving slowly to the north night by night. Stars shown to magnitude 8. Click for large version. Stellarium

At 338 miles across, Pallas bests Vesta in size by just 12 miles, making it the second largest asteroid after Ceres, the only main belt asteroid also classified as a dwarf planet. Unlike the planets, Pallas orbits the sun in a highly inclined orbit (34.8 degrees) taking 4.6 years to complete one spin around the sun. Pallas’ average distance from the sun is 257 million miles, but this month it’s lined up favorably with Earth and only about 115 million miles away. It was last this bright in 1991 and won’t be again until 2028.

Use this wide-field map to help you find Hydra and Alphard, its brightest star at 2nd magnitude. Alphard is roughly one “fist” held at arm’s length below and on either side of Procyon and Regulus. The map shows the sky facing south-southeast around 9 p.m. local time in early March. Stellarium

Being so much smaller than any of the eight planets, Pallas looks exactly like a star through most telescopes. Even the orbiting Hubble Space Telescope, located far above the blurring effects of Earth’s turbulent atmosphere, sees the asteroid as a pixelated object the shape of a flattened sphere with a large, darker “depression” that might be a crater.

The orbit of Pallas is rather wildly inclined, well outside the tilts of the other planets which lie in nearly the same plane. This view shows where Pallas is today March 3, 2014. Credit: NASA/JPL

Don’t expect a mission to the #2 anytime soon; Pallas’ highly tilted orbit makes it extremely difficult, energy and time-wise, to dispatch a probe for in-depth study and photo-taking.

Beautiful slice of the CR2 meteorite NWA 7837 from the Sahara Desert. Pallas’ surface shows similarities with this space rock. Credit: Sergey Vassiliev

That hasn’t stopped astronomers from eking out what they can across the millions of miles that separate us. Pallas receives light from the sun, absorbing some and reflecting the rest back into space. Rocks absorb light according to their internal makeup, imprinting their mineral signatures in the light they reflect back into space. Different rocks, different imprints.

Examining Pallas’ light with a spectrograph, which can dissect light like a doctor working a scalpel, we can identify basic minerals on the asteroid’s surface. From these observations, astronomers have learned that Pallas has much in common with the CR group of carbonaceous chondrite meteorites, both of which are very ancient and contain water and carbon.

This week Pallas will be near Alphard, an orange-tinted star and the brightest in Hydra, making it easy to find. It rides high in the southeastern sky around 9 p.m. local time. At magnitude 2 (Big Dipper brightness), Alphard stands out in a rather empty region of sky. You can find it by reaching your balled fist to Regulus in Leo and looking a little more than a fist below and to its right. Or you can do the same with Procyon in Canis Minor and look below and left.

Next, focus your binoculars on Alphard and use the map to stepping-stone your way to Pallas. The fun begins when you observe the asteroid for a second or third time and watch it move among the stars pulled by the gentle tug of the sun’s gravity.

‘Anybody want a peanut?’ Radar images of asteroid 2006 DP14

This image is one frame from a collage of radar images taken on Feb. 11, 2014, of near-Earth asteroid 2006 DP 14, which is about 1,300 feet (400 meters) long. Credit: NASA/JPL-Caltech/GSSR

On Feb. 10, asteroid 2006 DP14  zipped by Earth at six times the distance of the moon or 1.5 million miles (2.4 million km). One night later, astronomers used the 230-foot (70-meter) Deep Space Network radar antenna at Goldstone, Calif. to beam radio waves at the fleeing space rock and “take pictures” of it by measuring the returning radio echoes. At the time, the asteroid had receded to 11 times the moon’s distance.

Imagine their pleasant surprise when they discovered it was shaped like a giant space peanut.1,300 feet (400 m) long by 660 feet (200 m) wide. By the way, the headline refers to a famous rhyme by Andre the Giant in the movie The Princess Bride.

Radar movie shows asteroid 2006 DP14 rotating. The images were gathered over 2.5 hours and shows details as small as 60 feet across

Each lobe was probably a separate asteroid at one time. Circumstances allowed them to migrate toward one another through their mutual gravitational attraction, creating what astronomers call a “contact binary”. Ten percent of near-Earth asteroids larger than about 650 feet (200 m) have contact binary shapes. This tells us that there were times and places in the solar system (and may still be) where asteroids moved slowly enough relative to one another to join together. Just a hunch, but maybe it happened routinely in the solar system’s youth, helping to build the planets and larger asteroids.

Gaussian blur applied to the radar photo of 2006 DP14 reveals the smaller end of the peanut better as well as adding more three dimensionality to a couple crater-like depressions. Credit: NASA/JPL-Caltech/GSSR

As a little experiment to show the 2006 DP14′s topography and peanut shape more clearly, I apply a blur filter in Photoshop to the original image.

While this sounds counterintuitive, blurring removes the confusing pixelation and lets us see the essentials more clearly. At least to my eye. What do you think?

Radar is the best technique yet for resolving asteroid shapes, surface details and rotation rates. It can also pinpoint a space rock’s position with great precision, improving the accuracy of asteroid orbit calculations much farther into the future. This is critical to determining if a near-Earth object might become a collision threat or if will safely miss our planet.

Big boy asteroid 2000 EM26 flies by Earth tonight – Watch it live

Live feed for the tonight’s close approach of asteroid 2000 EM26

Sometimes I wonder how certain asteroids get picked for notoriety on the news while others don’t. Tonight, 2000 EM26 is in the spotlight. This near-Earth asteroid speeds by Earth at a distance 8.8 times that of the moon or about 2.1 million miles. Don’t get me wrong – that’s pretty close, and EM26 isn’t a particularly small rock. Based on its brightness curve, it’s estimated at 640 feet (195-meters) across.

Time exposure photo of the asteroid 2006 DP14 on Feb. 11, 2014. On Feb. 10 it passed just 1.5 million miles from Earth. Credit: Ernesto Guido, Nick Howes and Martino Nicolini

But a week ago on Feb. 10, the larger asteroid 2006 DP14 (2,395 feet / 730 m) made an even closer shave at 6.2 lunar distances. 2014 BR57 will pass closer yet at 4.4 times the moon’s distance on Thursday. I suspect the attention 2000 EM26 is getting is related to the Russian fireball, a near-Earth asteroid whose last orbit ended in earthly annihilation just one year ago.

Alright, alright, I’ll just quiet down and enjoy the show.

Show? Yes indeed. The wonderful, public-minded SLOOH – a fellowship of citizen astronomers who share the sky through free, live, public celestial events – will broadcast live views of 2000 EM26 as it tracks across the stars of the constellation Bootes starting this evening at 8 p.m. CST (9 p.m. EST, 2 a.m. Greenwich Time).

The orbit of 2000 EM26 – shown in blue – a near-Earth, potentially hazardous asteroid discovered on March 5, 2000. Credit: JPL/NASA

While the asteroid will appear perfectly star-like (it’s too small to show a shape), it will be cool to watch it crawl across the sky. Drawn by the power of the sun’s gravity, the same force that keeps Earth happily in orbit, the asteroid will travel to the northwest during the night, passing closest to our planet around 6 p.m. CST.

The live image stream will be accompanied by discussions led by Slooh host and astronomer Bob Berman with special guests including experts and eyewitnesses from Russia, who experienced a real asteroid impact on Feb. 15 a year ago, when the fireball rained down black stones over Chelyabinsk.

Sounds like a great time and a chance to refresh your knowledge of the largest witnessed meteorite fall in most of our lifetimes while simultaneously watching a potentially hazardous asteroid glide a safe distance from Earth.

You can really have it all in today’s world of astronomy.

Take a round-trip ride to the asteroid belt – send your name to Bennu!

As soon as you submit your name to travel to Bennu, you’ll get a certificate of your participation you can download and print out from your computer. Deadline to sign up is September 30, 2014. Click to hitch a ride. Credit: Bob King

NASA is inviting the citizens of Earth to send our names to asteroid Bennu. Just fill out the brief form and your name will be etched on the “Messages to Bennu!” microchip that will hitch a ride aboard the OSIRIS-REx (Origins-Spectral Interpretation Resource Identification Security Regolith Explorer) space probe in 2016.

The mission’s purpose is to return the first pristine samples of carbon-rich material from the surface of a primitive asteroid. Primitive asteroids are dark asteroids in the outer part of the asteroid belt that contain carbon, clays and water little changed since their formation at the dawn of the solar system 4.6 billion years ago.

Selection of radar images of asteroid 101955 Bennu, formerly known as 1999 RQ36, made with the Goldstone radio dish in Goldstone, Calif. in 2010. It doesn’t look like much but we’ll soon know it intimately. Credit: NASA

The probe, set to launch in September 2016, will rendezvous with Bennu two years later. Once in orbit, it will map and study the surface from a distance of between 3 and 0.4 miles (5 and 0.7 km) for 505 days. All the while your name will be there as a silent observer.

At some point during its stay, the spacecraft will extend the SAM or Sample Acquisition Mechanism down to the surface and collect at least 2.1 ounces (60 grams) of pristine material. The sample will be returned to Earth in a capsule that will float down by parachute over the Utah desert in September 2023.

Illustration showing OSIRIS-REx in orbit around asteroid Bennu. Credit: NASA

With a girth of about 1,600 feet (0.5 km) Bennu’s a larger than average Earth-approaching asteroid. It orbits around the sun every 436 days (1.2 years) and passes close to the Earth every six years.

During those close approaches, Bennu comes within 278,867 miles (448,794 km) of our blue orb. Calculation of its future orbits indicate that Bennu has one of the highest impact probabilities in the next few centuries of any known asteroid. Currently there’s a 1 in 1800 chance of impact with Earth on September 24, 2182.

Not only do scientists need to study the asteroid up close to gain a deeper understanding of the origin and evolution of asteroids and planets, but also to precisely determine its orbit and composition. In particular, we need to know how solar heating affects Bennu’s orbit.

Your name will be etched on two microchips – one on the spacecraft, which will remain in orbit about the sun for years and years, and one that will come home in the sample return capsule in 2023.

OSIRIS-REx will release the sample canister for re-entry back into Earth’s atmosphere and landing by parachute in Utah in September 2023. Credit: NASA/Goddard/University of Arizona

“It is exciting to consider the possibility that some of the people who
register to send their names to Bennu could one day be a part of the team
that analyzes the samples from the asteroid 10 years from now,” said Jason
Dworkin, mission project scientist at NASA’s Goddard Space Flight Center.

Like the mission on Facebook for mission updates, plus notifications on just where your name is from launch in 2016 to return to Earth in 2023. Check Twitter for late-breaking news.