A planet is a large celestial body that orbits a star, such as the Sun, and is massive enough for its gravity to shape it into a nearly round form. It must also have cleared its orbit of other debris. In our solar system, the eight recognized planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The word "planet" comes from the ancient Greek word meaning "wanderer," because planets appear to move across the sky relative to the fixed stars.
