Why Does the Moon & Earth Have Different Relationships with the Sun?

AI Thread Summary
The Moon is tidally locked to the Earth, meaning it always shows the same face due to the gravitational forces acting on it, which are proportional to 1/R3. The proximity of the Moon to Earth, its smaller size, and its irregular shape contribute to a much shorter tidal lock time compared to the Earth’s relationship with the Sun. While no planets are tidally locked, most close-in moons are, with Hyperion being a notable exception. The discussion raises the question of whether all orbiting bodies will eventually become tidally locked given sufficient time. Understanding these dynamics highlights the complex interactions between celestial bodies.
Martin Rattigan
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Why does the Moon keep the same face toward the Earth but the Earth not keep the same face toward the Sun?
 
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It's tidal locking. Tidal forces are proportional to 1/R3.

The Moon is much closer to the Earth than the Earth is to the Sun. The Moon is also much smaller than the Earth and much lumpier than the Earth. All of these things combine to make the tidal lock time for the Moon an extremely short time (astronomical time frame) while the tidal lock time for the Earth is very, very long.
 
I thought that was probably it. Do you know of anywhere that goes thro' the mechanics of that?

OK - I found something thro' Google - Thanks.
 
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Indeed, no planets are tidally locked, and almost all close-in moons are. (I think there is one exception - Hyperion) R3 is the reason.
 
I've wondered about this, for a while: Is it correct to assume that, given enough time, any orbiting body will become tidally locked?
 

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