This guide explains the Moon's phases in a simple, fun way for kids ages 8–12 — why they happen, what to call them, and a free printable worksheet to explore.
Why does the Moon change shape?
Here's the big secret about the Moon's phases: they are not caused by Earth's shadow. That would be an eclipse!
The Moon makes no light of its own — the Sun lights up one half of it. As the Moon travels around Earth, we see different amounts of that sunlit side. That's what makes it look like the Moon is changing shape.
The main phases of the Moon
When the sunlit side faces away from us, we can't see the Moon at all — that's a new moon. Over about two weeks it grows, or 'waxes', until the whole sunlit side faces us — a full moon.
Then it shrinks, or 'wanes', back to a new moon. The whole cycle takes about a month.
Not the same as an eclipse
It's easy to mix up phases with eclipses, but they're different. Phases happen every month as the Moon orbits Earth. An eclipse only happens once in a while, when the Sun, Earth and Moon line up just right.
The Moon's changing shape is also linked to the ocean's tides.
Explore the Moon and space at home
Learn all about our nearest neighbor in the Moon's Phases activity book, or explore the whole Space collection — with facts, activities and an Explorer Certificate.
A fun challenge tonight: look at the Moon and see if you can tell whether it's waxing (growing) or waning (shrinking).