What is the reason for Earth's rotation and revolution?

Question

Is it because of the gravitational effect of the other planets and the sun then why do the other planets rotate and revolve too? And well does the Sun rotate and revolve too?

Answer 1

Rotation is part of the process by which the astronomical bodies form. The gas, or the material that comes together to form the body, initially takes orbits and then comes together while rotating. Yes, sun rotates around it axis and it revolves around center of our galaxy Milky Way. After formation, due to tidal forces between earth and sun, the rotation speed (around its axis) slows down with time. Early earth days used to be smaller than 24 hours. Means earth was rotating faster and has been slowing down gradually. Same thing happened with moon and moon has already slowed down to no rotation, or the rotation rate is equal to revolution rate. Meaning, moon completes one rotation around its axis in same amount of time it completes one revolution around earth. So, same side of moon always faces earth. Moon also formed much closer to earth and has been inching away very slowly.

To understand how rotation is introduced - consider two bodies moving nearby with different velocities. They attract each other and come closer but do not quite bump into one another, but pass one another with speed. The slow down due to gravitational attraction and start approaching each other again. This process introduces a rotation of the two bodies. By the time the two bodies come together to become one, they are already rotating and due to conservation of angular momentum, even the merged body continue to rotate.

Even if the bodies initially bumped into one another (but not head on), they still would cause one another to rotate. Head on collision is rare. Also, when the bodies form, they are not formed from just 2 or so bodies. They are formed from gasses or random debris which ascertains rotation.

Answer 2

Well the simple answer is Earth was impacted with a large object in its' early life which caused not only the rotation but also spawned our moon. Part of NASA bringing moon rock home was to find out if we could link the moon to earth through the makeup of its' material and apparently they did. There are other planets like Venus which happens to orbit in the opposite direction but also it is due to an impact of another large body. You can hypothesize this theory once you study the large scar across the planets surface. The Sun also rotates as a ball of plasma faster at the equator and slower at the poles. But of coarse there are other things to consider other than the theory of our solar system forming solely on the principles of gravity as is the commonly accepted theory http://spaceplace.nasa.gov/review/dr-marc-earth/earth-rotation.html and perhaps the theory of the electric universe might unlock a new answer to your question https://www.youtube.com/watch?v=5AUA7XS0TvA and yes I think I saved the best link for last.