Binary Kuiper Belt object. Artwork of the distant Sun (upper centre) and a Kuiper Belt object (KBO, upper right), seen from the cratered surface of another KBO. These two KBOs are orbiting around each other, forming a binary system. The Kuiper Belt consists of a collection of icy, rocky bodies that range in size from small rocks to Pluto-sized objects, such as Sedna, Quaoar and 2003 UB313. Some consider Pluto and its moon Charon (which also form a binary system) to be KBOs. The Kuiper Belt extends outwards from the orbit of Neptune, past the orbit of Pluto, to about two times the Sun-Pluto distance. The Kuiper Belt is believed to be the source of short-period comets.