Science glossary film: Moon

A general name for a natural satellite of a planet, but also the specific name for Earth's only natural satellite. It has no atmosphere to speak of, one-sixth of Earth's gravity, and relative to its host planet it is the largest satellite in the Solar System. It was formed at about the same time as the Earth, probably as a result of a collision between the Earth and a small planet-sized object.

It has no atmosphere to speak of, one-sixth of Earth's gravity, and relative to its host planet it is the largest satellite in the Solar System. It was formed at about the same time as the Earth, probably as a result of a collision between the Earth and a small planet-sized object.