The NASA Hubble Space Telescope may have photographed the debris left over after two asteroids collided. Although such asteroid-asteroid smashups do happen in the Solar System, such a collision has never been seen before by anyone on Earth.





The February 2, 2010 NASA media brief ' Suspected Asteroid Collision Leaves Trailing Debris ' states that the comet-like object P/2010 A2 photographed by the Hubble Space Telescope shows ''¦a complex X-pattern of filamentary structures near the nucleus.'Because of how P/2010 A2 looks from the images so far taken of it, NASA thinks that the object contains a debris field that is left over from the collision of two asteroids.See it for yourself. A photograph of P/2010 A2 is found at the Astrosurf.com website , when it was taken on January 8, 2010.P/2010 A2 has an approximate 3.5-year orbit around the Sun. Its closest approach to the Sun--for its current orbit--occurred at the beginning of December 2009, about one month before it was discovered.The object was discovered by astronomers, on January 6, 2010, while using the sky survey Lincoln Near-Earth Asteroid Research (LINEAR) program.The LINEAR program uses a 1-meter (36-inch) reflecting telescope with a charge-coupled device (CCD) camera.Page two continues.For most of its life, the object is found within the warmer, inner regions of the asteroid belt'”within 2.7 astronomical units (AU) from the Sun (where one AU equals the average distance between the Earth and Sun).Past the 2.7-AU distance, most objects are comets, with cores made primarily of ice and secondarily from dust and gas. Closer than 2.7 AU, objects are usually asteroids consisting primarily of rocky-type material.The NASA article states, 'Asteroid collisions are energetic, with an average impact speed of more than 11,000 miles per hour, or five times faster than a rifle bullet."The images taken by Hubble --actually taken by its Wide Field Camera 3 (WFC3) instrument--show an estimated 140-meter (460-foot) diameter object that has characteristics similar to both asteroids (has an orbit of a main-belt asteroid) and comets (has a tail).However, it doesn't have a bright nucleus (center), which makes it a bit different than your normal looking comet.David Jewitt, of the University of California--Los Angeles, who is a principal investigator for Hubble, commented on P/2010 A2 within the NASA article.Dr. Jewitt said, 'This is quite different from the smooth dust envelopes of normal comets. The filaments are made of dust and gravel, presumably recently thrown out of the nucleus. Some are swept back by radiation pressure from sunlight to create straight dust streaks."And, "Embedded in the filaments are co-moving blobs of dust that likely originated from tiny unseen parent bodies."Page three continues.The Hubble images were taken on January 25, 2010, and three days later, on the 29th, when P/2010 A2 was approximately 145 million kilometers (90 million miles) from Earth and about 290 million kilometers (180 million miles) from the Sun.What is unique about this discovery is that the ''¦ main nucleus of P/2010 A2 lies outside its own halo of dust .... NASA states that, 'This has never been seen before in a comet-like object.'Consequently, astronomer think that this object is the result of a smashup of two asteroids.Dr. Jewitt adds, 'The filamentary appearance of P/2010 A2 is different from anything seen in Hubble images of normal comets, consistent with the action of a different process.'And, when astronomers first looked at this object they didn't see a bright center in its coma (filmy cloud-like material around its nucleus)Usually comets have bright centers, which indicate that they are outgassing icy particles.In addition, P/2010 A2 orbits the Sun totally within the warmer inner region of the asteroid belt where few icy bodies reside'”most of them are rocky bodies.Page four concludes.So, astronomers are conjecturing that P/2010 A2 does not consist of ice that has broken off from its nucleus and ended up in its debris trail.Instead, they think that the debris trail consists of rocky material that was ejected from two asteroids after they collided.Dr. Jewitt adds, "If this interpretation is correct, two small and previously unknown asteroids recently collided, creating a shower of debris that is being swept back into a tail from the collision site by the pressure of sunlight."NASA's article concludes with this statement: 'The asteroid belt contains abundant evidence of ancient collisions that have shattered precursor bodies into fragments. The orbit of P/2010 A2 is consistent with membership in the Flora asteroid family, produced by collisional shattering more than 100 million years ago.''One fragment of that ancient smashup may have struck Earth 65 million years ago, triggering a mass extinction that wiped out the dinosaurs. But, until now, no such asteroid-asteroid collision has been caught "in the act."For right now, astronomers are not sure whether P/2010 A2 is the result of two asteroids impacting each other and spewing out many smaller pieces. However, they are looking into the pictures provided by Hubble, and other such telescopes.For some background information on how P/2010 A2 was discovered, please go to the 1.10.2010 TransientSky.Wordpress.com article ' The Curious Case of Comet LINEAR .'