In this topic you will learn about the appearance and features of the Moon.

The Moon is a satellite of Earth. A satellite is anything that orbits another larger object in space. As the Moon orbits around Earth, it seems to change shape. The shape of the Moon does not really change. The amount of the Moon that can be seen changes. As the Moon orbits Earth, one side is always lit. As the Moon changes position, different parts of its lighted side are seen from Earth. The changing view of the Moon is called the Moon's phases. The Moon passes through all of its different phases once about every 29 days.

During the new moon, none of the lighted side of the Moon faces Earth, so we do not see the Moon. In the first quarter phase, we can see half of the lighted side, or one-fourth of the Moon. In the full moon phase, we see all of the lighted side of the Moon. In the last quarter phase, we see half of the lighted side, or one-fourth of the Moon.

The surface of the Moon is covered with a layer of dust. There are mountains and craters. A crater is a hollow area, or pit, in the ground. Most of the Moon's craters were made when chunks of rock or metal from space hit the surface of the Moon. The Moon does not give off any light of its own. It reflects light from the Sun. The Moon is both very hot and very cold. The side of the Moon facing the Sun is hotter than any place on Earth. On the side facing away from the Sun, it is much colder than any place on Earth.

Both Earth and the Moon rotate and revolve. They also both reflect light from the Sun. Earth is bigger than the Moon. Earth also has more gravity than the Moon has. Earth has air and liquid water. The Moon does not have either of these things, so scientists believe that there is no life on the Moon.