The  trans-Neptunian object (90377) Sedna was discovered in November 2003 by Michael Brown, Chadwick Trujillo, and David Rabinowitz. Its orbit is very elliptical, with a perihelion at 76 AU and an  aphelion at 975 AU. Its orbital period is about 11,000 years. Its diameter is estimated between 1,200 and 1,600 km and its albedo is about 0.16. It is of a dark red color with little methane or water ice, which suggests the presence of hydrocarbon deposits (or  tholins) on its surface. Sedna has been classified as a “detached”  trans-Neptunian object, which have also been called “extended-scattered” objects or “distant detached objects” (DDO), or as a member of the inner  Oort Cloud.