2006 redefinition of planet

The 2006 definition of "planet" by the International Astronomical Union (IAU) states that, in the solar system, a planet is a celestial body that:is in orbit around the Sun,has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape, andhas "cleared the neighborhood" around its orbit. A non-satellite body fulfilling only the first two of these criteria is classified as a "dwarf planet", whilst a non-satellite body fulfilling only the first criterion is termed a "small solar system body" (SSSB). The definition was a controversial one, and has drawn both support and criticism from different astronomers.
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