快猫短视频

DEBRIS in the main asteroid belt has allowed astronomers to reconstruct a collision that happened 5.8 million years ago, when a 3-kilometre rock shattered an asteroid more than 25 kilometres across, forming a family of at least 39 pieces more than 2 kilometres wide.

David Nesvorny of the Southwest Research Institute in Boulder, Colorado, found the group of asteroids by searching a database for objects with orbits of similar shapes and tilts, and low relative velocities. A computer model found that the orbits of the asteroids coincided 5.8 million years ago, a sign that they were once part of the same body.

The orbits of the fragments have had relatively little time to change since they were created, so the find gives asteroid researchers a chance to calibrate their computer simulations of what鈥檚 likely to happen when asteroids collide. Standard models predict that a collision would result in only one big fragment, but Nesvorny found both a 19-kilometre asteroid and a 14-kilometre asteroid. This could mean that the parent body was somehow fractured before the collision, he told 快猫短视频.

Other asteroid families have been common knowledge for years, but they are all hundreds of millions of years old, so time has obscured their origins. The new family鈥檚 youth makes it a tempting destination for spacecraft, says Derek Richardson of the University of Maryland in College Park. 鈥淟ike a geologist breaking a rock with a hammer, you get all these fresh pieces and you can study the interior.鈥�