text: The name of the tenth planet is 90377 Sedna.  90377 Sedna is a trans-Neptunian object, discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, 2003. At the time of its discovery it was the most distant observed natural solar system body, though this has now been exceeded by 2003 UB313 (a provisional name). \n\nThis particular scattered disc object, 2003 UB313, originally found in 2003 but confirmed two years later by Mike Brown (Caltech), David Rabinowitz (Yale University), and Chad Trujillo (Gemini Observatory), has renewed the old debate about what constitutes a planet since it is ~30% larger than Pluto with an estimated diameter of 1864 miles. It currently has no name, but has been given the provisional designation 2003 UB313, and has been nicknamed "Xena" by its discoverers, after the television character. It has many similarities with Pluto: its orbit is highly eccentric, with a perihelion of 38.2 AU (roughly Pluto's distance from the Sun) and an aphelion of 97.6 AU, and is steeply inclined to the ecliptic plane, at 44 degrees, more so than any known object in the solar system except the newly-discovered object 2004 XR190. Like Pluto, it is believed to consist largely of rock and ice, and has a moon. Whether it and the largest Kuiper belt objects should be considered planets or whether instead Pluto should be reclassified as a minor planet has not yet been resolved.\n\nSedna is described as a cold planetoid, perhaps as large as two-thirds the size of Pluto. Sedna, the newly discovered Pluto-like object with a gigantic, highly elliptical 10,500-year orbit that takes it from about 76 to 928 AU, has too distant a perihelion to be a scattered member of the Kuiper Belt and could be the first in an entirely new population. 2000 CR105 is also believed to be a member of this population.