Our cover picture ...
... shows the comet like object P/2010 A2 (LINEAR), which was discovered on 6 January 2010 with the 1m telescope of the Lincoln Near-Earth Asteroid Research project. The object moves around the Sun on an orbit between 2.0 and 2.57 AU. The observed tail formation seems unusual for this orbit, because the object is located within the so called ice line of 2.7 AU, where the volatile components should have outgassed long ago. On 25 and 29 January 2010, the new Wide Field Camera of the Hubble Space Telescope was pointed at the object and showed a sharply bounded dust tail and an X shaped coma with filamentary structures, which had never before been observed in such a form in comets. One possible explanation is a head on collision of two asteroids, in which the material spread around the remaining main body and produced the dust tail. Ground based observations support this theory, since no gases could be detected in the spectrum of the object. © NASA, ESA, and D. Jewitt (UCLA)
Download PDF