A planet is a large celestial body that orbits a star, such as the Sun. Planets are spherical in shape due to their own gravity and can be made of rock, metal, or gas. They do not produce their own light but reflect the light of their star. There are eight recognized planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. These planets vary in size, composition, and distance from the Sun, and they can have natural satellites, known as moons, that orbit them.