Introductionplanet [Gr., = wanderer], a large nonluminous body of rock or gas that orbits the sun or another star, has a rounded shape due to gravity, and has cleared its orbit of smaller objects. The term, once limited to any of the eight solid, nonluminous bodies (also called major planets) that revolve around the sun, has been extended to include similar bodies discovered revolving around other stars. The term planet sometimes has been used to include dwarf planets and asteroids (or minor planets); it does not include comets and meteoroids (see meteor. See also planetary science and planetary system, as well as the table entitled Major Planets of the Solar System.
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