The Moon, also known as Luna, is Earth's only natural satellite (the only object which orbits the Earth and is not man-made). It is usually visible in the night sky, but is sometimes seen during the day.

The Moon is about one-fourth of the width of Earth. Because it is so far away it looks small in the sky, about half a degree wide.

The gravity on the Moon is one-sixth of the Earth's gravity. It means that an object will be one-sixth as heavy on the Moon compared to Earth.

The Moon is a rocky and dusty place. It moves slowly away from the Earth at a rate of 3.8 centimeters per year due to the effect of tidal dissipation.

Some other planets also have moons or natural satellites. The giant impact hypothesis is a common explanation for how the Moon formed.