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The original was posted on /r/askscience by /u/Redditer0002 on 2023-08-06 01:49:21+00:00.


I watched Minute physics video about it and he says that the gravity of the Moon is stronger the closer you are to it. Therefor the water on the near side of Earth to the Moon is pulled more strongly which creates a bulge on the near side.

{This makes sense to me. The moon basically is canceling out some of the Earths gravity on the ocean nearest to the Moon.}

Then he says the water on the far side is weaker so it isn’t pulled as strongly which creates a bulge on the far side. This is the part I don’t understand.

On the far side of the Earth, the Moon’s gravitational force is weaker due to the greater distance. However, the Moon’s gravity still acts on the water, pulling it towards the Moon. The effect is that the water on the far side gets compressed more into the Earth, with the combined gravitational forces of both the Earth and the Moon working together to compress the water on that side.

Some may argue that the Earth is being pulled away from the water on the far side more strongly than the ocean is, causing the ocean to bulge outwards in the opposite direction. However, given the size of the Earth and the relatively small size of the ocean, this effect must be minuscule. The land beneath the ocean and the ocean itself experience essentially the same gravitational force from the Moon.