Thanks to the Hubble Telescope, for the first time ever, a planet has been di scovered with a tail.  Similar to a comet, the Jupiter-sized planet, 153 light years away, is shedding matter as it orbits its sun, forming a tail of of boiling carbon and silicon.

Creative Commons Image: Transiting planet HD 209458b by Alfred Vidal-Madjar (Institut d'Astrophysique de Paris, CNRS, France)