X-Rays from Comet LINEAR

Explanation: Why do comets emit X-rays? First discovered during the passing of Comet Hyakutake in 1996, the reason a cold comet would produce hot X-rays has since remained a mystery. On July 14, however, the orbiting Chandra X-ray Observatory was able to provide an image of passing Comet LINEAR , shown above , in enough detail to unravel the mystery. The key to the solution turns out to be the unusual wind of fast ions emitted by our Sun . These ions apparently collide with gas recently emitted by the comet and cause some ions to acquire a new electron . An electron that starts in a high-energy state will emit an X-ray as it falls in closer to the ion nucleus . As other comets move into the inner Solar System , this discovery should allow future study of the continually evolving gas cloud that surrounds comets as well as the composition of the solar wind .