The Moon

The Moon, also called "Luna", is by far the largest moon of any of the inner planets (in fact, it is larger than Pluto).

As it orbits around the Earth, the Sun shines on from different directions. This makes the Moon seem to change shape. We call these changes Phases of the Moon.

Unlike the Earth, the Moon has only a very thin atmosphere, far too thin for people to breath.

It is covered with many craters, caused by meteor impacts.

Some areas are darker and have fewer craters. These are called "Maria" (latin for Seas) because early astronomers thought that they were old oceans. We now know that they are actually big areas of solid lava, left over from when the Moon was much younger and hotter inside.

It is not really known how the Moon was made, but it was probably "broken off" the Earth while it was forming.

It is the only place other than the Earth to have been visited by humans (on July 20th, 1969).

Because of the effect of tides over many millions of years, the Moon always has the same face towards us.

You can find out more about the different features you can see on the Moon here.

Facts and Figures
Orbit	384,000 km from the Earth
Radius	1,738 km
Mass	7.35 x 1022 kg or 0.012 Earths
Length of "Year"	27.32 Earth days
Length of Day	27.32 Earth days
Surface Gravity	0.165 g
Surface Temperature	about 150 °C on the day side about -150 °C on the dark side