US astronomers image asteroid with long tail

U.S. astronomers said on Monday that they have found the tail of a peculiar asteroid much longer than previously supposed, stretching roughly three times the distance from the Earth to the Moon. The tail of dust streaming from the asteroid P/2010 A2 is about one million kilometers long, according to new images taken by One Degree Imager (ODI), a wide-field optical camera at the WIYN telescope on Kitt Peak in the U.S. state of Arizona. Asteroids generally have no tails, and asteroid A2 was initially given a cometary designation upon its discovery in 2010. But it's an asteroid. Within a month of its discovery, analysis of images taken by the U.S. Hubble space telescope suggested that its tail was generated by dust and gravel. Researchers said this suggested that A2 was disrupted recently, either by a collision or by its own rotation. "Previous images of A2 clearly indicated the tail extended beyond those relatively small fields of view: we wanted to use the superb image quality over a wide field that ODI offers to see just how much," said Jayadev Rajagopal, WIYN scientist at the U.S. National Optical Astronomy Observatory, in a statement. "But I don 't think we were quite expecting to see a tail that extends out to and beyond even the ODI field!" The disruption of asteroid A2, which the team estimates happened about three and a half years ago, has resulted in centimeter-sized particles being spread out in a tube-like tail. Over time, these particles, under the gravitational pull of the Sun, will form a meteor stream surrounding the Sun, said the researchers.