How do planets and moons stay within the rotation of their respective larger bodies, without being pulled in?

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How do planets and moons stay within the rotation of their respective larger bodies, without being pulled in?

In: Physics

If you throw a rock, it follows a curved path as it falls towards to the ground. If you throw it harder, the curve is larger. If you through it really really hard (17,500 mph), the curve of the rocks path is the same as the diameter of the earth. It’s still falling towards the ground. It’s just going fast enough to ‘miss’ the ground.

They are being constantly pulled by the larger body. However, they have a huge amount of tangential momentum keeping them from falling in. That is, they have a horizontal velocity high enough that, as their are pulled towards the other body, by the time they “fall,” the curvature of the large body has fallen away, so they just keep falling around it instead.

Better explained by the relevant xkcd: https://what-if.xkcd.com/58/