House-sized asteroid makes close Earth flyby Monday / See dawn’s ghostly finger

Gianluca Masi used a 17-inch telescope to track the motion of asteroid 2014 UF56 on October 25. The small space rock will pass just 102,000 miles from Earth Monday afternoon CDT. Credit: Gianluca Masi

Discovered only yesterday, Earth-approaching 2014 UF56 will violate our planet’s personal space on Monday October 27th. At around 4 p.m. Central Daylight Time the ~45-foot-wide (14-m) boulder will tumble by at less the half the distance of the Moon.

With 90% of near-Earth asteroids larger than 0.6 miles (1 km) discovered, surveys are now focusing on finding 90% of objects larger than 460 feet (140-m). We have to take it a step at a time because the total number of near-Earth asteroids is in the millions. That’s why objects like 2014 UF56 pop up regularly in surveys each month. Every discovery adds one more piece to the grand puzzle that astronomers have been painstakingly assembling since the very first Earth-approaching asteroid, 433 Eros, was discovered in 1898.

The speedy boulder was found only yesterday. Despite passing so close to Earth, few if any of us will see the flyby with our eyes in a telescope. At brightest, 2014 UF56 will only reach magnitude +16, the limit for a 16-inch telescope, as it zips from Scutum through Capricornus. But you’ll be able to watch its mad dash all the same. Gianluca Masi, an Italian astrophysicist, will have his observatory open for business and stream the close passage live on his Virtual Telescope Project site starting at 2 p.m. CDT (7 p.m. UT) Monday October 27.

A cone of soft light tilts up from the eastern horizon about 2 hours before sunrise on October 22. The planet Jupiter is seen near its tip. Called zodiacal light, it’s sunlight reflecting off dust left by passing comets and asteroid collisions. Now through about November 4 is the best time to see the sight for northern hemisphere observers. Credit: Bob King

Earlier this week I went out before dawn to watch the Orionids, an annual meteor shower that originates from bits of dust and rock shed by Halley’s Comet. Every year during the third week of October we encounter Halley’s dregs and watch them fire up as meteors when they strike the atmosphere 70 miles over our heads. While only a few streaked the sky that morning, my outing coincided with the best display of another much larger phenomenon intimately tied to dust left behind by passing comets – the zodiacal light.

I look forward every fall to seeing the subtle beauty of this large, finger-shaped glow poking up from the eastern horizon. For northern hemisphere observers, it’s best visible before the start of dawn or about 2 hours to 90 minutes before sunrise. Then it towers more than halfway up in the eastern sky titled at about a 60-degree angle to the horizon.

The zodiacal light cone, which is centered on the Sun’s path through the zodiac called the ecliptic, tilts upward in late October reaching up to and even beyond the bright planet Jupiter. Credit: Bob King with Stellarium

To see the zodiacal light, you’ll need a dark, light pollution-free sky view of the eastern sky. and the will to arise “in the darkest hour”. It’s broadest and brightest near its base – similar to the summer Milky Way – but fades and tapers as you lift your gaze toward the bright planet Jupiter, now stationed near its tip.

The phenomenon gets its name from the “zodiac”, a band of a dozen constellations the Sun, Moon and planets pass through during their monthly, yearly and multi-year travels across the sky. When a comet’s orbit takes it within the inner solar system, the Sun vaporizes a portion of its ice, releasing dust and small rocks into space to create the comet’s coma and tail. Much of this dust is left behind in and near the mid-plane of the solar system where it forms a cloud of debris. Illuminated by scattered sunlight, we see it as the skinny-tipped finger of zodiacal light.

Crossed swords of light! The zodiacal light (left) meets the Milky Way in this beautiful image taken on October 1 this year. Though they’re similarly bright and large, the zodiacal light has a smooth texture without the clumpiness that characterizes the Milky Way. Credit: Damian Peach

During fall mornings and spring evenings, northern hemisphere skywatches see that mid-plane tilted up at a steep angle, high above the horizon hazes that would otherwise block the light from view. That’s what makes now an ideal time to set out for a look.

Much of the glowing comet dust will spiral into to the Sun over time and vaporize; a constant stream of comets, old and new, keeps it replenished. Near as I can figure, the zodiacal light is the single, largest visible structure in the solar system.  And to think it’s built of something as insubstantial as comet dust.

Asteroid 2014 RC makes astronomers’ heads spin / Crater appears in Nicaragua

Multiple images of asteroid 2014 RC made with the Lowell Observatory 42-inch Hall telescope showing its motion on September 7, 2014.

Not only did it make a very close approach to Earth yesterday, but astronomers got a better handle on 2014 RC’s size and how fast it spins during the flyby.

The space rock was originally thought to be 60-feet (20-m) across but we now know it’s closer to 40-feet (12-m) or about the size of a school bus and spinning very rapidly. Try one rotation every 15.8 seconds!

That makes 2014 RC the fastest rotating asteroid (by 50%) observed to date. Astronomers using NASA’s Infrared Telescope Facility (IRTF) on September 6 observed the space rock in infrared light to determine its composition. It reflects about much light (25%) as green grass and belongs to the “Sq class” of stony asteroids. Rocky asteroids are the most common kind. Based on its reflectivity, 2014 RC is much brighter than a typical comet and several other classes of asteroids.

The suspect crater near the Managua airport. Credit: AP

In a story begging to be related but isn’t, a purported meteor crater showed up near Managua, Nicaragua’s international airport this weekend. Whatever caused  it, the blast occurred during the early morning of September 6th, 13 hours before 2014 RC’s close flyby, which passed beneath Earth’s orbit anyway. A loud bang was heard and the ground shook, but there are no eyewitness reports or video of a meteor or meteorite fall. The crater is about 40 feet (12-m) across.

The surest way to confirm if a meteorite fell would be to look for fragments in and around the crater. No news yet on that. I’ll update when more information becomes available.

Discover the 644,633 asteroid – New citizen science program is addictive, fun

While most Earth-approaching and potentially hazardous asteroids 1 km and larger have been discovered, there are many thousands of smaller objects still waiting to be found and tracked. You can help scientists do it by participating in the Asteroid Zoo project, an offshoot of Zoouniverse, a citizen science Web portal, and Planetary Resources.

Enjoy the satisfaction of finding the missing TV remote in the house when your spouse inadvertently puts it in the refrigerator?  If you have those sort of finely-honed hunting instincts, then the Asteroid Zoo needs you.

2013 map showing the orbits of over 1,400 potentially hazardous asteroids. 140 meters across and will pass within 4.7million miles of Earth — about 20 times the distance to the Moon. None is expected to strike our planet within the next 100 years. Click to enlarge. Credit: NASA/JPL-Caltech

The new citizen science project offers everyone a chance to discover new Earth-approaching objects (NEOs) through crowdsourcing. Asteroid Zoo uses over 3 million photos shared by the Catalina Sky Survey. Your goal is to click is to find moving dots – asteroids – as the multiple images ‘flicker’ before your eyes. This is similar to the way American astronomer Clyde Tombaugh found Pluto back in 1930 using a blink comparator. You’ll also find artifacts like digital noise or bits of fuzz in some of the photos, which the survey wants you to note as well.

There are 644,632 known asteroids in the solar system at the moment. Who know – you might just discover the next one. Asteroid Zoo plans to use the results of the project to find near Earth asteroid (NEA) candidates that will be used in scientific papers and research. Some may even prove to be possible targets for future exploration.

Screen grab from Asteroid Zoo showing a typical search image with viewing options. Credit: Zooniverse

Click HERE and then press the ‘start hunting’ button. You can choose to learn more about the program or immediately start hunting asteroids. The interface is extremely well thought out and very easy to use. Click ‘Play’ to see four images run in a loop. If an asteroid’s been caught in the sequence, it will scoot across the photos while the stars remain still.

The ’4 up’ option for asteroid picture selection. Credit: Zooniverse

You can choose to watch either an animated loop or four static images – the ’4 up’ option. There’s even an ‘invert’ option to shows white stars on a black sky instead of the default black stars on white.

I found the hunt easy and addictive like a cellphone video game. After 35 searchers I flagged a number of artifacts and actually found one asteroid, though it had already been discovered earlier.

Anyway, give it a try. You can do as few or many as you like and come back anytime you want. What an easy way to participate in science with the added carrot that anyone could make an important discovery.

To stay on top of developments, check out the Asteroid Zoo blog.

Two ‘Planet Xs’ may lurk unseen beyond Pluto

Orbits of the remote asteroids 2012 VP113 and a potentially unseen ‘Planet X’ 10 times more massive than Earth that may shape their orbits. Now, some astronomers think there may even be a second large planet orbiting even farther out. Also shown are the Kuiper Belt and Neptune’s orbit. Credit: Scott S. Sheppard/Carnegie Institution for Science with additions by the author

The planets are coming! The planets are coming! Only months after announcing the possibility of a ‘Planet X’ 10 times Earth’s mass orbiting 250 times Earth’s distance from the sun, a team of Spanish astronomers think there may be another massive planet hiding even deeper in the inky depths.

While this artist’s concept shows how the inner solar system would appear from the surface of distant asteroid Sedna. The view from a hypothetical Planet X would be similar. Credit: NASA/ESA/ A. Schaller

In March this year, astronomers reported the discovery of 2012 VP113, an asteroid that orbits farther from the sun than any previously known. 2012 VP113 joins Sedna and a number of other asteroids beyond the outer asteroid belt (Kuiper Belt) whose orbits are aligned in a way that hints at the gravitational influence of a possible planet farther out. Scientists calculate that this world would be about 10 times the mass of Earth and orbit at roughly 250 times Earth’s distance from the sun.

Carlos and Raul de la Fuente Marcos at the Complutense University of Madrid in Spain have taken another look at these distant bodies. As well as confirming their bizarre orbital alignment, the pair found additional puzzling patterns, according to a recent article in New Scientist.

This NASA graphic shows the orbits of Pluto and Neptune. Their paths cross twice every 248 years, but because of the way the orbits are timed, Pluto and Neptune are in no danger of colliding. Credit: NASA

Too small to tug on one another, the team attributes the similarity of their orbits to the ‘shepherding’ influence of a larger unseen body in a pattern called orbital resonance.

We see orbital resonance at play with Neptune and Pluto. The two worlds exert a regular and repeating gravitational attraction on each other causing their orbits to be related by a simple whole number ratio. For every 2 orbits Pluto makes around the sun, Neptune makes 3.

Similarly, 2012 VP113 and friends appear to revolve as a group in lockstep with a distant world with a mass estimated between that of Mars and Uranus and orbiting 200 times Earth’s distance from the sun. Some of these remote asteroids have orbits that take them out to that distance – that’s where a second large planet may play a part.

Since it would be unusual for a distant shepherding planet to orbit so close to its ‘sheep’ unless it too were in resonance with yet another large body, the Spanish team suggests that another ‘Planet X’ 250 times the Earth-sun distance pulls the strings as it were. Their numbers square nicely with the distance predicted in the earlier work on Sedna and 2012 VP113.

For now, 2012 VP113, shown here slowly moving across the sky, is the most distant solar system object seen. It was discovered with the new Dark Energy Camera at the National Optical Astronomy Observatory’s 4-meter (157-inch) telescope in Chile. At closest, it’s 80 times the Earth-sun distance. Credit: Scott Sheppard / Carnegie Institution for Science

Spotting any new Planet Xs will be extremely tricky. The remote asteroids travel along very elongated orbits that periodically take them close enough to the sun for us to photograph them. ‘Close’ is a bit of an exaggeration. Sedna, for example, only pulls up to 76 times the Earth-sun distance at best where it tops out at a feeble magnitude +20.5. Any planets beyond are expected to follow more circular orbits similar to the familiar inner solar system gang and glow ever so faint.

Heat-radiating planets as large as the ones predicted and at the distances suggested, should have been detected by NASA’s WISE space probe’s infrared survey. But WISE’s two complete infrared sweeps of the sky found that no object the size of Saturn or larger exists out to a distance of 10,000 times the Earth-sun distance (10,000 AUs or astronomical units) and no object larger than Jupiter exists out to 26,000 AUs. Still, WISE had its limits. A remote planet colder than about -330 F (-201 C) could escape detection.

Naturally, the results don’t preclude these smaller objects. While hypothetical for the moment, larger telescopes both on Earth and in orbit may one day coax these putative Planet Xs into the light.

For more information on the topic, check out the team’s scientific paper.

What’s this? A 1,300 foot long space peanut?

Radar video of 2014 HQ124 showing the peanut-shaped asteroid rotating on its axis with a period of about 20 hours.

Every month a couple Earth-approaching asteroids fly close enough past Earth to make great targets for radar imaging. On June 8, the 1,300-foot (305-meter) asteroid 2014 HQ124, discovered in April, flew pass the planet at a distance of just 800,000 miles (1.3 million km). Hours after closest approach, astronomers used the 230-foot (70-meter) Goldstone Deep Space Network antenna California to beam radar signals at the asteroid, which obligingly reflected them back – imprinted with information about its shape, contours and rotation speed – to the 1,000-foot (305-meter) dish at Arecibo Observatory in Puerto Rico.

This ‘game of catch’ using the largest radio telescope on Earth dramatically improved the amount of detail that can be seen in radar images. A recent equipment upgrade at Arecibo enabled the two facilities to work in tandem to obtain images with this fine level of detail for the first time:

A selection of radar images of the peanut-shaped 2014 HQ124 on June 8, 2014. The asteroid is probably a ‘contact binary’, two asteroids that were once close enough to each other that they touched and stuck together through mutual gravitational attraction. Click to enlarge. Credit: NASA/JPL-Caltech/Arecibo Observatory/USRA/NSF

“This may be a double object, or ‘contact binary,’ consisting of two objects that form a single asteroid with a lobed shape,” said Lance Benner of NASA’s Jet Propulsion Lab. The images reveal a wealth of other features, including a puzzling pointy hill near the object’s middle, a large, dark depression and possible boulders lying on the surface.

A little over 2,000 feet long, asteroid Itokawa, like 2014 HQ124, is a contact binary comprised of two separate bodies. It also exhibits a classic ‘rubble pile’ structure built of rocks that have cohered over time. Credit: JAXA

About 1 in 6 asteroids is a contact binary. Possible scenarios for their formation include impacts that shatter larger asteroids which then reassemble into ‘rubble piles’ of busted boulders. One of the best-imaged of these rocky-road melanges is 25143 Itokawa, an asteroid visited and sampled in 2005 by the Japanese space probe Hayabusa.

For asteroids, as well as comets, radar is a powerful tool for studying the objects’ size, shape, rotation, surface features and orbits. Radar measurements of asteroid distances and velocities enable researchers to compute orbits much further into the future than if radar observations were not available.

Close flyby of asteroid 2014 KH39 June 3 / Camelopardalid meteor shower ‘radar rich’

Diagram showing the orbit of 2014 KH39. Yellow shows the portion of its orbit above the plane of Earth’s orbit (grey disk); blue is below the plane. When farthest, the asteroid travels beyond Mars into the asteroid belt. It passes closest to Earth around 3 p.m. CDT June 3. Credit: IAU Minor Planet Center

Next Tuesday afternoon June 3, asteroid 2014 KH39 will silently zip by Earth at a distance of just 272,460 miles (438,480 km) only a little farther than the moon. To be exact, it will miss us by 1.14 lunar distances (LDs). Close as flybys go but not record-breaking. The hefty space rock will buzz across the constellation Cepheus near the Little Dipper at the time. Pity it will be too faint to spot in amateur telescopes, but astrophotographers might want to give it a whirl.

2014 KH39 was discovered on May 24 by the automated Mt. Lemmon Sky Survey. Further observations by the survey and additional telescopes like the Pan-STARRS 1 observatory in Hawaii nailed down its orbit as an Earth-approacher with an approximate size of 72 feet (22-m). That’s a tad larger than the 65-foot Chelyabinsk asteroid that exploded into thousands of small stony meteorites over Russia in Feb. 2013. Three large fragments weighing a total of 1,442 lbs. were also found at the bottom of Chebarkul Lake.

Cool infographic depicting asteroids that will make close approaches to Earth in the next 200 years. Vertical axis shows distance in thousands of km from the asteroid to Earth’s center. Click it to see a larger, easy-to-read version. Credit: Rianovosti

Since this asteroid is not on a collision course with Earth we have nothing to fear from the flyby. I only report it here to point out how common near-Earth asteroids are and how remarkable it is that we can spot them at all. While we’re a long ways from finding and tracking all potentially hazardous asteroids, dedicated sky surveys turn up dozens of close-approaches every year.

Take today for instance. 2014 KF22, estimated at 56 feet across (17-m) is making its closest approach to Earth at 2.67 LDs as I write this sentence. On June 8, 2014 HQ124 will pass 3.3 LDs away. That one’s BIG with a diameter estimated at more than 2,100 feet (650-m) and close enough to glow at magnitude +13.7. Amateur astronomers with good maps should be able to track it in 8-inch and larger scopes.

This all-sky radar map by the Canadian Meteor Orbit Radar (CMOR) shows a hot spot of meteor activity at the ‘Cams’ radiant near Polaris on May 24. The shower produced about 100 meteors per hour as seen by radar. Credit: Dr. Peter Brown /CMOR

While we’re on the topic of things buzzing through space, more results from the May 24 Camelopardalid meteor shower have been published. You’ll recall that rates of at least 100 per hour were predicted but most of us saw 1/10 that rate at best. Guess what? We really did get the higher number except they were about a magnitude too faint to see with the eye even from a dark sky site.

Video clip by John Chumack of bright Cams flashing over Dayton, Ohio on May 24, 2014

The Canadian Meteor Orbit Radar facility picked up plenty of Cams with ‘underdense’ echoes, according to Dr. Peter Brown of the University of Western Ontario. Underdense means faint – most Cams were magnitude 6-7 — at and below the naked eye limit. Larger particles, which produce brighter meteors, had been forecast, but now we know that the shower’s parent comet, 209P/LINEAR, shed finer debris more like dust than pebbles.

We’ll have to wait until 2022 and 2045 for the Cams to return. Maybe by then Google Glass will be available in a radar version.

Sentinel Mission would spy ‘city-killing’ asteroids in the nick of time

B612 foundation video showing locations of 26 asteroid impacts between 2000 and 2013

Poor Earth. Always getting whacked by asteroids. Now it’s time to do something about it. This week, the B612 Foundation, a private organization dedicated with protecting the planet from potential asteroid impacts, announced plans to build the Sentinel Infrared Space Telescope to detect Earth-approaching asteroids long before they get here.

The Chelyabinsk meteoroid / asteroid, here seen from a dashcam video, was the largest impact in Earth’s atmosphere recorded by the nuclear test ban treaty network’s infrasound’s sensors since 2000. Before it exploded into smaller pieces, the asteroid measured about 65 feet across.

Data recently released from the Nuclear Test Ban Treaty Organization, which operates a network of sensors that monitors Earth around the clock listening for the low frequency infrasound signature of nuclear detonations, recorded 26 large explosions in the atmosphere not from weapons but rather from small asteroid impacts. The largest of them was the headline-making Chelyabinsk fireball that exploded in the atmosphere with the force of 600-kilotons of TNT on Feb. 15, 2013. To put this in perspective, the atomic bomb that destroyed Hiroshima had the energy of 15 kilotons.

Another fireball over Murmansk, Russia reminiscent of Chelyabinsk occurred Saturday night April 19. No sounds or explosions were heard but the object burned briefly as bright as the full moon. Video courtesy: Alexandr Nesterov

Most of the 26 impacts were smaller than Chelyabinsk and detonated high in the atmosphere over uninhabited regions like the oceans. Asteroid impacts greater than 20 kilotons occurred over South Sulawesi, Indonesia in 2009, the Southern Ocean in 2004, and Mediterranean Sea in 2002.

“While most large asteroids with the potential to destroy an entire country or continent have been detected, less than 10,000 of the more than a million dangerous asteroids with the potential to destroy an entire major metropolitan area have been found by all existing space or terrestrially-operated observatories,” stated Lu, CEO and co-founder of B612. “Because we don’t know where or when the next major impact will occur, the  only thing preventing a catastrophe from a “city-killer” sized asteroid has been blind luck.”

Sentinel would circle the sun inside Earth’s orbit and look outward to spy incoming Earth-crossing asteroids. The B612 Foundation hopes to raise private money to build the probe. Credit: B612 Foundation

The B612 Foundation (named after the asteroid in the novella “The Little Prince”) will partner with Ball Aerospace to privately build the Sentinel spacecraft that would launch in 2018 into a Venus-like orbit on a 6.5 year mission to find and track 90% of the asteroids larger than 460 feet (140 meters) with orbits that intersect Earth’s. It will also search for smaller asteroids in the 30-45 meter range, large enough to destroy a major city should our luck go bad. B612 estimates an asteroid this size strikes the planet about every hundred years.

Potentially hazardous asteroid 4179 Toutatis photographed by the Chang’e 2 spacecraft during a 2012 flyby. The asteroid is 2.8 miles long. Credit: CNSA

Sentinel will create a comprehensive map detailing the paths of asteroids during the next 100 years, giving earthlings decades of notice to alter their course through one of several imaginative but untested methods.

The Foundation believes that asteroid impacts rates have been underestimated and are 3-10 times more common than previously thought. While some would argue that number is overstated, there’s no denying that discovering more potentially hazardous objects is a good thing. Sentinel scientists hope to find some 500,000 large enough to pose a threat.

This is no fly-by-night operation. B612 was co-founded by Ed Lu, a former Shuttle and Soyuz astronaut, and has links with NASA, which will provide communications, navigation and tracking for the mission with its Deep Space Network.

To learn more about the topic, click HERE for a FAQ on hazardous asteroids and HERE to donate money to the mission.

If you can find Mars, you can spot Ceres and Vesta too – try it!

Ceres, the largest asteroid, and Vesta, the brightest, lurk near the bright planet Mars this spring. They’re easy to see in binoculars and showed up clearly in this 30-second time exposure made April 20, 2014. Credit: Bob King

Who hasn’t been dazzled by the Red Planet these April nights? Come 10 o’clock, Mars shines brilliantly in the south accompanied by the the blue-white star Spica. But did you know that just a short distance away, asteroids Ceres and Vesta are making their rounds in the night sky too?

Use this map to get started. The star to find is labeled Zeta Virginis, located a little less than one outstretched fist to the left of Mars. Point your binoculars there and then use the more detailed map below to navigate to Ceres and Vesta. Stellarium

Ordinary binoculars will easily show both. Last night I stood in my driveway with a pair of 8x40s and hopped from Mars to Zeta Virginis and then to the “Vesta Triangle” and saw them in the same field of view. Vesta shines at magnitude 5.8, bright enough to be dimly visible with the naked eye from a dark sky. Talk about easy. I hardly had to try with binoculars.

Ceres and Vesta hang out this month  near the “Vesta Triangle”, a small group of stars located about 3 degrees north of Zeta. Positions for both asteroids are shown for 10 p.m. CDT every five days with stars to magnitude ~8.5. The stars will remain in their places, but you’ll see Ceres and Vesta move slowly among them as the nights pass. Click to enlarge, then print to use outside. Created with Chris Marriott’s SkyMap software

Ceres, at magnitude 7, is fainter but well within easy reach from suburban skies. Now the cool part – both asteroids will be no more than a few degrees apart through July. That means they fit in the same binocular field of view, so if you find brighter Vesta, Ceres will always be nearby. Matter of fact, they’ll really get close come late June and early July. As we approach that time, I’ll provide additional maps.

Vesta (left) and Ceres. Vesta was photographed up close by the Dawn spacecraft from July 2011-Sept. 2012, while the best views we have to date of Ceres come from the Hubble Space Telescope. The bright white spot is still a mystery. Credit: NASA

If you’ve never seen an asteroid before except in close up photos taken by spacecraft, lower your expectations right now. They look exactly like stars. Even Ceres, the largest at 590 miles in diameter, is too small to appear more than stellar in even a large telescope. Vesta’s smaller yet – 330 miles wide – but brighter because it’s somewhat closer and also more reflective.

That’s OK. Getting to see the real thing is what skywatching’s about. I love the photos but honestly get more of a kick out of seeing the asteroids with my own eyes. When life gets tedious, I like to think of them silently cycling over my little patch of earth, Vesta 114 million miles away, Ceres 153 million.

Dawn’s Greatest Hits at Vesta – A Look at What We Learned (spiced up with guitar)

Coincidentally, both Vesta and Ceres, which orbit in the main asteroid belt, are the targets of NASA’s Dawn Mission. Dawn visited and studied Vesta from July 2011 to Sept. 2012 and revealed that the tiny world had something much in common with its big brothers, the planets. Vesta was once hot enough to melt and differentiate into an iron core, rocky mantle and crust like the terrestrial planets. Heat from the decay of radioactive elements like aluminum-26 caused heavier iron to trickle down to the core while lighter minerals floated to the top to form Vesta’s crust.

Ceres rotates once on its axis every 9 hours (Vesta takes 5.3 hours). These four photos span 2 hours 20 minutes. Photos taken with the Hubble Space Telescope. Credit: NASA/ESA

While Ceres can still be considered an asteroid it’s also a member of a select group of dwarf planets, bodies large enough to have crunched themselves into spheres through their own gravity but not big enough to clear the region they orbit of smaller asteroids. Dawn’s on its way to its final target, a rendezvous with Ceres next February. Unlike dry and rocky Vesta, Ceres shows signs of water and clay.

While you’re waiting for the next close up photos, why not go out on the next clear night and see them for yourself?

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!