| Found in | Work cat.: 2006037345: Kaspar. A. A look at Pluto and other dwarf planets, 2007: galley (Scientists define dwarf planets as objects that are round and orbit the sun, but share their orbits. Dwarf planets are also smaller than planets)
IAU Web site, Nov. 8, 2006 (At the 2006 General Assembly of the International Astronomical Union a new distinct class of objects called dwarf planets was decided. It was agreed that planets and dwarf planets are two distinct classes of objects. The first members of the dwarf planet category are Ceres, Pluto and 2003 UB313 (temporary name). A dwarf planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.)
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