OtterKnow Kids Encyclopedia

Have you noticed that the Moon looks different on different nights? Sometimes it is a big bright circle, sometimes it is a thin sliver, and sometimes you cannot see it at all! These different shapes are called moon phases.

Moon phases happen because the Moon orbits around Earth. As it moves, the Sun lights up different parts of the Moon that we can see. When the whole face is lit up, we call it a full moon. When just a sliver is lit, it is a crescent moon. The Moon goes through all of its phases in about one month, then starts all over again!