Satellite

Satellite, in astronomy, celestial object that revolves with or around a large celestial object. In our Solar System this includes planets, comets, asteroids, and meteoroids, as well as the moons of the planets, although the term is usually restricted to this last sense. Of the dozens of known moons, the largest is Callisto (Jupiter IV); the smallest, Phobos (the inner moon of Mars). The earth's moon is the largest known satellite relative to its parent planets; indeed, the earth-moon system is often considered a double planet.

See also: Astronomy.