Yeah, sort of. We know the moon is made of mostly the same stuff as earth, with some differences. And on earth we see some similarities in different proportions. It's those slight differences that lead to the theory of another celestial body colliding. Then they run millions of different models with varying sizes, material compositions, initial conditions (spin, momentum, direction, etc.) and then look for convergence of the models with current or known conditions. If you've got a number of models that tend to show the conditions we see, then you can theorize that you're on the right track.
The earth's spin is only one of the aspects. The moon doesn't spin, but rather wobbles slightly, as it's tidally locked. I'd imagine it was spinning atbone point and because tidally locked due to proximity and gravitational effects (this is fairly common with systems with a larger and a smaller body).
I thought tidally locked meant it spins at the same rate of its orbit. So it does spin but also moves around earth at the same rate. Thus the slight wobble…is my understanding incorrect?
Yes, it spins once per orbit, but does not spin relative to earth. It likely used to spin much more, but gravitational forces over time slow that to lock it with the earth's rotation. My point wat that it's not spinning the same as it would have when it was formed.
Another fun fact, the moon moves further away from the Earth because angular momentum is being transferred from the Earth to the moon. Angular momentum transfer is due to the tides. As a result, the Earth’s rotation is slowing. According to Wikipedia, 620 million years ago, the day was 21.9 hours long and there were 400 days a year.
same, mine always thinks we should be up an extra hour or so no matter what we did yesterday. it's miserable trying to keep it on earth schedule. maybe i really am the alien i feel like sometimes.
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u/Universe_XoX 8h ago
That actually does kinda make sense, never thought about it like that before.
So pretty much the momentum of that impact is still being shown right now in the lunar and earth spinning.