University of Edinburgh

BSL Physics Glossary - moon - definition

Planets often have natural satellites orbiting them - going round and round. Here on planet Earth we have one moon. You can see it in the night sky. It's a natural satellite which takes 28 days to orbit round the earth. When we look at the moon, it appears white. This is because light from the sun hits the moon and is reflected back to us on earth. We call the moon a natural satellite of the Earth.