Last January, the Hubble Space Telescope captured images of a strange X-shaped object in the head of what astronomers thought could be a comet, and dubbed itP/2010 A2. Five months later they discovered that they were facingfirst imagesthan it seems to bea recent collision between two asteroids. Researchers from the Max Planck Institute for Solar System Research (Germany) and the University of California in Los Angeles (United States) report their observations in ‘Nature’, dating the collision sometime in early 2009.
When astronomers discoveredP/2010 A2, its ‘headless’ appearance and the orbit on the inner margins of the main asteroid belt – between the orbits of Mars and Jupiter – made them doubt that it was a comet, and wonder if it was an asteroid with a tail instead of a a member of a newly recognized class of main belt kites.
German scientists, led by Colin Snodgrass, observed the object thanks to the space probeRosetta, which was approaching the asteroid belt on its way to the asteroid Lutetia. And after observing the images they came to the conclusion thatthe object’s tail is made up of debris from the collision of two asteroids. The object is expanding with a slowness that has surprised astronomers.
On the other hand, David Jewitt’s team, from the University of California, took high-resolution images with the Hubble space telescope between January and May 2010, and estimated the object’s core at a diameter of 120 meters, while they detected millimeter dust particles on its tail.
Scientists estimate that collisions like this occur once a year, but capturing the collision of asteroids is difficult because large impacts are rare, while smaller ones, such as the one that produced P / 2010 A2, are very faint.
