The moon is a planet, a satellite of the Earth. It revolves around the earth which in turn revolves around the Sun.
A complete revolution around the Earth makes the Moon 27 days and 8 hours, at the same time it rotates around its axis. That's why we always see one side of the moon. But in 1959 to the moon was launched by the Soviet aircraft, and he photographed the back side of the moon, which we until then had no idea.+
The moon is a dead heavenly body: there's no atmosphere, no water, therefore, life is simply impossible. The light of the moon is only a weak reflection of the sunlight. So it seems that many times the Moon changes appearance during the month.
When the Sun illuminates the hidden side of the moon, we cannot see at all. The moon is a relatively small planet: in diameter it's 4 times smaller than Earth. The distance from the earth to the moon — from 365600 to 406800 km, depending on the mutual arrangement of planets.