50000 Quaoar

50000 Quaoar ("Kwawar") is a Kuiper belt object roughly half the size of Pluto, with a diameter of 7003111000000000000♠1110±5 km. It is large enough and massive enough that it is probably a dwarf planet. Its orbit in the Kuiper belt is not in resonance with Neptune, which means it is a classical Kuiper belt object. Quaoar has one known moon, Weywot.

Quaoar was discovered in 2002 and its moon in 2007. It was named after the Tongva creator deity and its moon after his son.

Signs of water ice have been found, which suggests that cryovolcanism may be occurring. A small amount of methane is present on Quaoar's surface, which can only be retained by the largest Kuiper belt objects.

Discovery

Quaoar was discovered on June 4, 2002 by astronomers Chad Trujillo and Michael Brown at the California Institute of Technology, from images acquired at the Samuel Oschin Telescope at Palomar Observatory. The discovery of this magnitude 18.5 object, at the time located in the constellation Ophiuchus, was announced on October 7, 2002, at a meeting of the American Astronomical Society. The earliest prediscovery image proved to be a May 25, 1954 plate from Palomar Observatory.