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A non-luminous body in orbit around the Sun, or another star, which has sufficient mass to have become rounded by its own gravity and which has significantly cleared its orbital neighbourhood of smaller objects. Planets can consist of rock and metal, as do the inner planets of the Solar System, or predominantly of liquid and gas, as do the giant outer planets. The term does not include comets or other small objects such as meteoroids. Asteroids, however, are sometimes referred to as minor planets. A planet can have a mass up to about 10 times that of Jupiter, above which it would become a brown dwarf. In 2006 the International Astronomical Union introduced the term dwarf planet to describe objects that are rounded in shape but which have not cleared the neighbourhood around their orbit; this category includes the largest member of the asteroid belt and the largest trans-Neptunian objects.

Subjects: Astronomy and Astrophysics.

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