all 7 comments

[–]UmamiTofu 3 insightful - 1 fun3 insightful - 0 fun4 insightful - 1 fun -  (0 children)

The Moon is moving at a very high speed. It tries to keep going forward past the Earth, but the Earth's gravity pulls it downwards. These balance out to keep it falling in a circle around the Earth.

[–]roc 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (3 children)

The moon doesn't fall apart because it has enough mass to create significant gravity. At the surface of the moon the gravitational acceleration is 1/6 of Earth, which means that pieces of the Moon cannot just drift away into space. Gases however can easily escape with 1/6 gravity, which is why the Moon has no atmosphere.

[–]wizzwizz4[S] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (2 children)

Why do gases drift away, but stones not? Doesn't everything fall down?

[–]roc 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (1 child)

Because molecules in a gas all move with some speed. This speed can be high enough to a body's gravity. Rocks on the other hand do not move around but lie in one place.

[–]wizzwizz4[S] 0 insightful - 1 fun0 insightful - 0 fun1 insightful - 1 fun -  (0 children)

Great explanation! You're missing the word "escape", though.

[–]zyxzevn 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (1 child)

<EX5>The moon falls down continuously. It just happens that the Earth also moves away from it, just to avoid any collision.

[–]Afor 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (0 children)

What? No, that's not how it works. It balances nearly perfectly between "falling to earth" and "getting slung into space".