Eli5: Tidal lock of moon – I have a very specific question about how this works – please see link

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[https://moon.nasa.gov/resources/429/the-moons-orbit/](https://moon.nasa.gov/resources/429/the-moons-orbit/)

OK so here is my question: this video looks like the moon is revolving around the earth but that it is not rotating on its axis at all. The earth is doing both in the video clearly and the moon “sees” other sides of the earth – b/c the earth is rotating. How exactly is the moon rotating WITHOUT turning? I assume it is turning b/c I’ve read that it does in fact rotate but I cannot wrap my brain about how it is working – how does something turn in front of you without you ever seeing the other side of it? And if it is b/c it is turning at the exact rate as the earth, why does the moon see the other side of the earth? Why aren’t they both locked? This question has bothered me for years and I’ve watched a bunch of videos on it and I just don’t get it and I feel stupid and I promise I’m not. LOL. Please – help me understand this.

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4 Answers

Anonymous 0 Comments

You can literally see the Moon rotating in the animation. Look at the lunar maria (the dark grey splotches on the Earth-facing side of the Moon) and you can see that they are always facing the Earth. If the Moon didn’t rotate as it orbited the Earth, that would not be true. When the moon is at the top of screen, the lunar maria are facing towards the bottom of the screen, and when the moon is at the bottom of the screen, the maria are facing the top. That’s half a rotation. The moon completes one rotation in the same amount of time to complete an orbit.

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