Why do planets revolve around themselves? Why didn't the moon fall to the earth?

Rotation is caused by the contraction of the nebula when the planet forms, resulting in rotation. The huge mass brings huge inertia, and there is no resistance and friction in space, so it has been spinning ever since.

Revolution is also the rotation caused by the contraction when the nebula is formed. The center forms a rotating main star, which is formed around its satellite. The centrifugal force around prevents the satellite from falling to the main star.

The moon is said to be the "son" of the earth and the big stars in space. It is different from the satellite formation mentioned above, but it also has centrifugal force around the earth, which is slightly greater than the gravity of the earth, so it is getting farther and farther and will not fall.

The combustion of gas, oil and gunpowder is an oxidation reaction, which is extinguished after the reaction (combustion). The sun is a nuclear reaction and goes out when the reaction is over. Now the reaction is in the middle. If you want to see it go out, just wait.