Why does the moon change shape?

When your child asks, here's how to answer — in their words, and in yours.

For your child

The moon doesn't really change its shape! It's always a round ball. We just see different amounts of its lit-up side as it moves around Earth and the sun shines on it.

Heads up

The answer simplifies by not using terms like 'orbit' or 'phases' or describing the geometry of the Earth-Moon-Sun system. These concepts can be introduced once the child has a stronger grasp of spatial relationships and cycles.

For you

The phases of the Moon are due to the changing angles at which we view the Moon's illuminated surface from Earth. As the Moon orbits Earth, the amount of sunlight reflected from its surface that is visible to us changes over its roughly 29.5-day cycle. The Moon itself is always a sphere, half of which is always lit by the Sun, except during an eclipse.

They might ask next

Does the sun shine on the whole moon all the time?
Can the moon make its own light?
What do we call the different moon shapes?

Whyzard answers your child's own questions — out loud, in words they'll understand.