The Moon does not change shape
A thin curve one night. A full circle two weeks later. Does the Moon change shape?
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Step 1 of 4
- The Sun always lights one half of the Moon.
- Near the Sun's side: Earth sees the dark half. New Moon.
- Far round the orbit: Earth sees the lit half. Full Moon.
- Same lit half each time. Only the view changes.
The rule
No: we see a different part of the same Moon.
An orbit is the path round something. The Moon orbits Earth in about a month.
The Sun always lights one half of the Moon. This is the lit half. That half never changes size.
The Moon moves round Earth. So we see more or less of the lit half.
A phase is how much of the lit half we can see.
At New Moon, we see none of the lit half. At Full Moon, we see all of it.
Watch out!
Earth's shadow does not make the Moon's phases. The Sun lights half the Moon all the time. Only our view of that half changes.