Planets

For an astronomical body to be classed as a planet it much adhere to the following criterion: it must be in orbit around the Sun, it must be massive enough to reach hydrostatic equilibrium and form a rounded shape and lastly it must have cleared the neighbouring region around its orbit of other large bodies. Our Solar System has five dwarf planets and seven planets. In order of increasing distance from the Sun the planets are: Mercury, Venus, Mars, Earth, Jupiter, Saturn and Uranus, some, but not all, of which have moons.

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