# Question why does the moon move around the earth

question why does the moon move around the earth why it doesnt hit the earth under the effect of gravity??

because the moon is moving with a velocity that is the orbital speed, so it stays in orbit

stable orbits are possible because gravity follows an inverse square law
if gravity followed an inverse cube law then all orbits would be unstable and would eventually spiral outward to infinity or inward to the planet surface.

shobat, do a google search on "Newton's orbital cannon".

the moon is actually moving with more velocity then the velocity orbital speed, so it is moving around a millimetre away from the earth every year

because the moon is moving with a velocity that is the orbital speed, so it stays in orbit
but why did the moon have orbital speed in the first place and how does it have the same energy to continue with same speed (this question about satellite and other planets too).

DaveC426913
Gold Member
but why did the moon have orbital speed in the first place
The prevailing theory is that the Moon was created when a collision occurred between Earth and another body. This sent much of protoEarth flying in a spray of rubble. The fate of the rubble can be classified into three categories:
- rubble that acquired little kinetic energy simply fell back to what remained of the Earth, becoming part of the current Earth.
- rubble that acquired a lot of kinetic energy was lost from the Earth system
- rubble that had juuuuuuust enough kinetic energy ended up neither falling back to Earth, nor escaping completely. This rubble continues to this day to ride the narrow line between falling back to Earth and escaping completely. We call it the Moon.

and how does it have the same energy to continue with same speed (this question about satellite and other planets too).

It requires no energy to stay in orbit.