Sedna is not a planet. It is more likely to be a dwarf planet that orbits very far away from the sun. Some astronomers, however, are reluctant to place it in that category because it is so far away that observing it is difficult.
As of 2014, Sedna is the furthest object from the sun that has been discovered within the Solar System. It is the first object discovered that is considered to exist in the hypothetical region of the Solar System known as the Oort Cloud, which may be filled with comets and other icy objects. Scientists believe that it could take anywhere from 10,000 to 12,000 Earth years for Sedna to orbit the Sun. Sedna appears to be red in color, almost as red as Mars. Astronomers believe the color may be due to hydrocarbon or tholin.
Sedna was named after an Inuit goddess who obtained immortality when she drowned in the ocean. According to legend, Sedna protects sea creatures and lives at the bottom of the Arctic Ocean. Because of the extremely cold temperatures in the Oort Cloud, the astronomers who found Sedna recommended that names from the mythology of the Arctic region should be used to name any future objects found there.