Sedna
Introduction
Sedna is trans-Neptunian object that was discovered by Michael Brown, Chad
Trujillo, and David Rabinowitz, when a survey was conducted at the Palomar
Observatory in San Diego. It was studied by observatories all over the world.
When the planetoid was discovered, it was the farthest object from the Sun ever
discovered in the Solar System. Sedna was named because of its distance from the
Sun and the cold on the planetoid. It was hence named after the Inuit Goddess of
the Sea, Sedna, who was believed to have lived in the Arctic Ocean.
Planet Category: Trans-Neptunian Object
Substitute Name: 2003 VB12
Discovered: November 14, 2003
When Sedna was discovered, it was the largest trans-Neptunian object found since Pluto. It has an estimated diameter of 1180 to 1800 km and is now thought to be the 5th largest trans-Neptunian object after Eris, Pluto, 2005 FY9, and 2003 EL61. Observations show that Sedna is the reddest space object next to Mars. Unlike Pluto and Charon, Sedna appears to have very little methane ice or water ice on its surface. It was suggested that Sedna's dark red color is caused by a hydrocarbon sludge, or tholin. Sedna is rarely hit by other bodies and mabye that's why its surface is homogenous in color and spectrum.
Sedna was found to have an unusually long rotational period when it was first discovered. Investigations were made to see if a natural satellite cause this but nothing was found. When Sedna was observed again by the MMT telescope, it was found to have a shorter and more sensible rotational period of around 10 hours. When first observed, Sedna was found to have an elliptical orbit.Aphelion at around 975.5 AU and its Perihelion at 76.16 AU. Before Eris was discovered, Sedna was thought to be the farthest object from the Sun.
The argument at first was that Sedna was part of the Oort cloud because it was too far out to be considered part of the Kuiper Belt. But Sedna is a lot closer to the Sun than is expected for an Oort cloud object and has an inclination that is roughly so it has been termed as being part of the Inner Oort cloud. Sedna, along with a few other objects discovered prompted suggestions of a new category of distant objects named: Extended Scattered Discs, Detached Objects, and Distant Detached Objects.
