Answer card
Why does the Moon change shape?
Want to guess first?
Write a guess down before you look, and you will notice what surprises you. You can’t get it wrong.
What we know
- True: “The Sun always illuminates half of the Moon while the other half remains dark, but how much we are able to see of that illuminated half changes as the Moon travels through its orbit.” NASA Science — Moon Phases
- True: “The cycle repeats about once a month (every 29.5 days).” NASA Science — Moon Phases
What we made simpler
The Moon does not really change shape. It is always round; what changes is how much of its sunny side faces us.
Still open
Not much: scientists understand the phases well. How the Moon formed in the first place is still argued about.
Next why
Why do we always see the same side of the Moon?
StarForge — predict the Moon’s phase →Try it
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