Quaoar is a ringed dwarf planet candidate in the Kuiper belt, a band of icy planetesimals beyond Neptune. It has a slightly ellipsoidal shape with an average diameter of 1,100 km (680 mi), about half the size of the dwarf planet Pluto. The object was discovered by American astronomers Chad Trujillo and Michael Brown at Palomar Observatory on 4 June 2002. Quaoar has a reddish surface made of crystalline water ice, tholins, and traces of frozen methane.