spacetoday.net: Large planetoid found in outer solar system

Posted: Tue, Mar 16, 2004, 7:40 AM ET (1240 GMT)
Sedna illustration (NASA/JPL/Caltech)

Astronomers announced Monday the discovery of a large body that is the most distant object in the solar system, an object that could be part of the Oort Cloud. The object, officially known as 2003 VB12 but provisionally known as Sedna, was discovered by Caltech astronomers at Palomar Observatory in November 2003. Followup observations by other telescopes, including NASA's new Spitzer Space Telescope, confirmed that the object was located in the far out reaches of the solar system. The object is in a highly-elliptical orbit that takes the object as far as 900 AU (130 billion kilometers) from the Sun; the object was found when it was near the perihelion of its 10,500-year orbit, at a distance of 13 billion kilometers. Infrared observations by Spitzer revealed that the object is the largest body in the solar system discovered since Pluto in 1930: its diameter of 1,700 kilometers is smaller than Pluto but larger than any other asteroid of Kuiper Belt object (KBO) found to date. Astronomers believe this object is not a KBO but instead may be a body flung inwards from the Oort Cloud, a hypothesized shell of icy bodies at the far outer edges of the solar system. Sedna may also have a small moon orbiting it, based on observations to date, although more studies will be needed to confirm the moon's existence.