Why the moon doesn’t fall down to the earth? We know that the moon travels in speed perpendicular to the gravity of the earth so that it doesn’t fall down to earth. But what if we supposed that the moon is stationary and the earth is stationary also but rotating around its axis? I drawn the attached two charts to explain my question:

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    $\begingroup$ It does fall towards earth, but it "falls" sideways as well, so it goes in a circle, same idea as the international space station. The moon is not stationary, nor is the earth. Read this post physics.stackexchange.com/q/9049 $\endgroup$ – user81619 Sep 13 '15 at 18:55
  • $\begingroup$ Already Newton's Laws of motion explain this. Only assuming there is an attractive force of the form he gave, and his Three Laws of motion, one can find that the relative angular momentum is what prevents them from approaching. In the case you are proposing, the moon would just fall in a straight line. $\endgroup$ – rmhleo Sep 13 '15 at 19:01

If the earth and moon were both stationary initially, the moon would fall into the earth as you said. But they were not. Earth was moving around the sun when the moon was formed from the earth. And so the moon also started revolving around the earth. Infact even now the moon is falling towards the earth, but the earth is continually moving away so that the moon has to continually change the direction of it's fall.

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    $\begingroup$ otherwise known as conservation of angular momentum $\endgroup$ – anna v Sep 13 '15 at 19:15

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