A Satellite is a celestial body that moves around the planets in the same way as the planets move around the sun. The Satellites or Moons revolve round their mother planets or primaries. The Solar System is known to have 166 satellites or moons. Of these Jupiter claims 64, Saturn 60, Uranus 27, Neptune 13, Mars 2, and Earth 1. Mercury and Venus have no satellites or Moons.
Among satellites, Earth's Moon is distinguished in two ways. First, it is only a satellite. All planets other than the Earth either have no satellites or have more than one satellite. Second, the Moon is proportionately the biggest is size compared to the mother planet. Our Moon is one-fourth of the size of the Earth.
The Moon has a diameter of 3475 km as against the Earth's 12700 km. But it has a surface less than half that of the Atlantic Ocean. Its gravitational pull is about one-sixth of the Earth's. It is about 3,84,400 km away from the Earth.
The Moon revolves round the Earth in 27 days 7 hours 43 minutes and rotates on its own axis in exactly the same time. As a result, only one side of the moon is visible to us on the earth.
The near side (front side) of the Moon seems to be made up of bright and dark patches. The bright parts are the mountains and highlands that receives the Sun's rays, while the darker patches are low-lying plains. The Moon has no atmosphere, as its gravitational power is too weak to hold down gases. There is no sound either as sound is a vibration transmitted through air.