If two asteroids collide in space, what happens?
Astronomers using NASA’s Hubble telescope suspected they’d find something akin to a hand-grenade explosion when they located what looks like an asteroid collision from early 2009.
But over time, the collision formed a “bizarre X-shaped object at the head of a comet-like trail of material,” according to a prepared statement from NASA released Wednesday.
The object appears to be expanding very slowly, astronomers said.
Asteroid collisions aren’t unusual; scientists estimate they crash into each other once a year. But this is the first time a telescope has recorded the collision causing an X-shaped pattern with debris.
Astronomers said that indicates something besides “comet outgassing” is happening.
Here’s NASA’s best bet about what transpired:
Astronomers think a smaller rock, perhaps 10 to 15 feet wide, slammed into the larger one. The pair probably collided at high speed, about 11,000 mph, which smashed and vaporized the small asteroid and stripped material from the larger one. Jewitt estimates that the violent encounter happened in February or March 2009 and was as powerful as the detonation of a small atomic bomb.
Astronomers still do not have a good explanation for the X shape. The crisscrossed filaments at the head of the tail suggest that the colliding asteroids were not perfectly symmetrical. Material ejected from the impact, therefore, did not make a symmetrical pattern, a bit like the ragged splash made by throwing a rock into a lake. Larger particles in the X disperse very slowly and give this structure its longevity.