1Two things to know first
A trip around, and a spin of its own
A moon can do two different turns. Watch each one happen:
It orbits Earth
The Moon takes one big trip around Earth — about a month to go all the way around the circle.
It can spin too
A moon can also spin on its own, like a top — turning around its own middle while it travels.
2The mix-up at the heart of it
Two ways a moon could travel
The "never spins" idea 🚫🌀
Lots of people guess the Moon must be frozen still — never spinning — to keep one face toward us. Keep this idea in mind…
The "one spin per trip" trick 🌀
Or maybe it spins exactly once each time it goes around. Which one actually keeps the same face pointed at us?
3Drive a moon that does NOT spin
Push it around — with its spin switched off
Here is a moon with a gold face painted on one side, and no spin of its own. Drag it around Earth and watch which way the gold face keeps pointing.
Its painted face keeps pointing the same way out into space, no matter where it is. So sometimes the gold face aims at Earth… and sometimes it aims away.
Earth has seen: the gold face4Predict, then watch a whole month
So… is the Moon spinning, or frozen still?
You just saw that a moon with no spin would swing its back into view. The real Moon never does — it keeps one face on us forever. Before you watch a whole month go by, make your guess: is the Moon spinning at all?
Guess before you watch
The real Moon keeps the same face toward Earth night after night. To pull that off, what is its own body doing as it travels around us?
Watch one full month: the moon spins once as it goes around. Keep your eye on the gold face…