The three asteroids Quaoar (discovered in 2002), Eris (or 2003 UB313, discovered in 2003), Orcus (discovered in 2004) and the asteroid Sedna (discovered in 2003) are the largest known asteroids: their diameters exceed 1000 km. Their motions are very slow and it is especially the motion of the Earth which gives a noticeable apparent motion on a background of fixed stars.

Right, the comparative sizes of these bodies. Eris, larger than Pluto, is the origin of the change of the definition of a planet. If Quaoar has a nearly circular orbit (above, Q red = Quaoar, P = Pluto), Sedna has a highly elliptical orbit and its distance from the Sun varies between 76 and 927 astronomical units (between 11 and 139 billion miles). The latest measurements suggest that ultimately that Eris is larger than Pluto.