Scientists are over the moon at the W.M. Keck Observatory and the California Institute of Technology over a new discovery of a satellite orbiting the Solar System's 10th planet (2003 UB313). The newly discovered moon orbits the farthest object ever seen in the Solar System. The existence of the moon will help astronomers resolve the question of whether 2003 UB313, temporarily nicknamed "Xena," is more massive than Pluto and hence the 10th planet. A paper describing the discovery was submitted to the Astrophysical Journal Letters on October 3, 2005. "We were surprised because this is a completely different type of...