Why the Moon changes shape
The Moon does not make its own light. It shines because sunlight bounces off it. As the Moon moves around the Earth, we see different amounts of its bright side. These different shapes are called the phases of the Moon.
Key idea
The Moon looks like it changes shape because we see different parts of its sunlit side as it orbits the Earth.
The main phases
At the new moon we cannot see the Moon at all. Then a thin crescent appears. It grows to a half moon, and then to a bright, round full moon. After that it shrinks back again. One full cycle takes about 29 to 30 days, which is roughly one month.
Example
When you see a big, round, bright Moon in the night sky, that is a full moon. About two weeks later, you will see no Moon at all — a new moon.
Remember
- The Moon does not make its own light.
- The shapes are called phases.
- One full cycle is about one month.