Phases of the Moon
Why does the Moon change shape?
Duration: 1:47
Some nights the Moon is big and round, other nights it looks like a thin banana. Let's find out why the Moon seems to change shape!
In short
The Moon is always a big round ball: it never really changes shape. It does not make its own light; the Sun lights up one half of it. As the Moon travels around the Earth, a trip that takes about one month, we see more or less of its bright side. At new moon the bright side faces away from us. A few days later we see a thin crescent, then half of the bright side at first quarter, and finally the whole bright side: a full moon. These different shapes are called the phases of the Moon, and then they start all over again.
What you will learn
- The Moon is always a big round ball
- The Moon shines because the Sun lights it up
- The Moon travels around the Earth in about one month
- New moon, crescent moon, first quarter and full moon
- Why the phases start all over again
Let's talk about it
Questions to ask after watching, at home or in class. Tap a question to see a short answer.
Does the Moon really change shape?
No. The Moon is always a round ball: we just see more or less of the half that the Sun lights up.
Where does the Moon's light come from?
From the Sun. The Moon makes no light of its own; the Sun lights up one half of it.
How long does the Moon take to travel around the Earth?
About one month. That is why the phases come back again about every month.
