The Moon

Some planets have over 30 moons, but the Earth only has one. The Moon takes 27.3 days to orbit the Earth - the basis of our calendar month.

Anything in space that revolves around another body is called a 'satellite'. So the Moon is a natural satellite of Earth.

It probably formed when another planet hit the early Earth. The rocky debris eventually fused to form the Moon.

Take a trip to the the Moon.