“X” Marks the Spot

Hubble spots asteroid impersonating a comet

With a long trail of material streaming out into space one would assume this to be a photo of a comet…but it’s not. Rather, it’s believed to be the result of a collision between two asteroids that produced a weird X-shaped pattern of filaments emanating from a small remnant object. Material from the filaments has since been blown back into space by solar radiation.

P/2010 A2

This object, called P/2010 A2, was first discovered on January 6 by the LINEAR (Lincoln Near-Earth Asteroid Research) Program and appeared unusual enough in ground-based observations that they  had the HST take a better look at it. The resulting image, above, was taken on January 29. (The blue coloration was added later for better visibility.)

Unlike their science-fiction movie counterparts, asteroids rarely encounter each other…but when they do the results can be impressive. Colliding at over five times the speed of a rifle bullet, asteroids can literally blow each other to bits. It’s been theorized that the asteroid belt is slowly being worn down by impacts but this is the first time the result of one has been seen directly.

“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.”

– David Jewitt, Principal Investigator, UCLA

Read more on the Hubble site here.

Image: NASA/ESA and D. Jewitt (UCLA)

UPDATE: Later observations with Hubble from January to May 2010 showed that the comet-like tail expanded very slowly, indicating that the collision itself likely occurred early in 2009…a high-speed collision between a 400-foot-wide object and a 10 to 15-foot-wide object with the force of a small atomic bomb. Read more here.

P/2010 A2 observations from January 29 to May 29, 2010

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