The International Astronomical Union defines "planet" as a celestial body that, within the Solar System that is in orbit around the Sun; has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape; and has cleared the neighbourhood around its orbit; or within another system, it is in orbit around a star or stellar remnants; has a mass below the limiting mass for thermonuclear fusion of deuterium; and is above the minimum mass/size requirement for planetary status in the Solar System. Our solar system is thus considered to have eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Under a separate resolution, it is also considered to have three dwarf planets: Ceres, Pluto, and Eris.
There have been more than two hundred planets discovered orbiting other stars to date.
For more information about the topic Planet, read the full article at Wikipedia.org, or see the following related articles:
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