Any celestial body revolving around other celestial body is known as is satellite. For example, Moon revolves around earth in definite orbit, so moon is a satellite of earth. Generally, the celestial body is known as a satellite of another celestial body if and only if the other celestial body is a planet. Like, Moon revolves around the earth, and earth is a planet therefore, moon is a satellite of earth. Although we can say that earth is a satellite of sun but generally we call it as a planet of sun. The term satellite is generally used when the motion of a celestial body is around a planet.
