The Moon rotates on its axis and orbits the Earth at the same rate, about once every 28 days. Tidally locked in this configuration, the synchronous rotation always keeps one side, the nearside, facing Earth.
That has always struck me as odd. Seems like a near impossibility that both the moon's rotation and its orbit around Earth would be precisely the same.
The mass may not be symmetrical. If one side has more mass it will have more gravitational attraction to Erf.
It also wobbles around a bit, so astronomers get to peek over the edges just a bit. I was looking for this image, but thought it would be from a different Freeper. I didn’t remember that I’d posted it in the past.
https://freerepublic.com/focus/chat/3691563/posts?page=4#4
It’s often called tidally locked, the physics term is ‘tidal transfer of momentum’. That means that a body in (prograde) orbit around another body (and indeed, the parent body also experiences tidal transfer of momentum) loses rotational momentum as it pushes against the other body.
Presumably the Moon used to have a faster rate of rotation, but thanks to the fact that the Earth is about 100 times the mass of the Moon, the Moon ran out of rotational momentum first.
The Earth continues to push the Moon away and lose a tiny bit of rotational momentum as it does this. Dunno the math, but it’s possible that the Earth will push the Moon far enough away that the Moon will be lost, at least for some period of time. That’ll be a bad crazy day, but it won’t be anytime soon.
The wobble in the pic at the top link is probably due to the lumpiness of both Earth and Moon:
Earth:
https://freerepublic.com/focus/news/952189/posts
https://freerepublic.com/focus/chat/2697901/posts
https://freerepublic.com/focus/chat/3237279/posts
Moon:
https://freerepublic.com/focus/news/2186775/posts
Mercury:
https://freerepublic.com/focus/chat/3286370/posts
My guess is, the Chandler Wobble is due to the lumpy Earth and lumpy Moon interactions:
https://freerepublic.com/tag/chandlerwobble/index?tab=articles
“Seems like a near impossibility that both the moon’s rotation and its orbit around Earth would be precisely the same.”
Given geometry and gravity it is a certain.
It is tidally locked. Think of the moon as a pendulum. The minimum energy configuration is with the bob or weight at the lowest point. The only two bodies in the solar system that are known to be mutually tidally locked are Pluto and its “moon” Charon. Charon and Pluto are more of a double planet than moon and major body, the center of mass of the Pluto-Charon system is well outside of Pluto.
The center of mass of the Earth-Moon is only about one third of the way below the surface. The Earth and moon actually orbit a point that lies about 4000 kilometers from the center of the earth on the line connecting the center of mass of the moon and earth. It is the center of mass of the Earth-Moon system that orbits the sun. Both the earth and moon orbit their center of gravity every 27.3 days with respect to fixed stars, 29.53 with respect to sun.
#7 you are close to the answer. We are in a diorama in some alien kids classroom project.