Haumea is a dwarf planet in the Solar System. Its discovery was announced in 2005 by astronomers Michael E. Brown, Chad Trujillo and David Rabinowitz of the United States, and J. L. Ortiz of Spain. It was classified as a dwarf planet on September 17, 2008. Haumea is a Trans-Neptunian object, because it orbits the Sun after Neptune. It has two known moons, Hiʻiaka and Namaka. Haumea is special because of its very short day and odd shape. It turns once on its axis every four hours. This quick turning has caused Haumea to be shaped like an ellipsoid. It was the fifth discovered dwarf planet.