Why the Moon changes shape: always half lit, and only part of it faces you
30seconds
Ask why the Moon changes shape and most people blame the Earth's shadow. It is a natural guess, and it is wrong: the Moon is half lit by the Sun all the time.
What changes is the angle. Drag the Moon around its orbit and watch how much of its lit half faces you, why a month of phases takes 29.5 days rather than 27.3, and why the Moon rises about 50 minutes later each night.
Deep dive · 4 min
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