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Mystery #1Tier 2space / the Moon

Why does the Moon change shape through the month?

Over a month the Moon swells from a thin crescent to a full circle and shrinks away again. It can't actually be changing shape. So what makes the same round Moon look so different night to night?

The full Moon, lit by the Sun
Photo: Gregory H. Revera · CC BY-SA 3.0 · via Wikimedia Commons

Your guess

What's your hunch about why the Moon seems to change shape over the month? (It isn't Earth's shadow!)

There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.

Make a guess to unlock the hints and the answer.