Hi Dogrock, you question:

?I've entered "why do planets move" on the internet but got only gravity as the answer. Maybe no one knows why (not in the philosophical sence but by what force)they move.?

I feel you are sincere and welcome a response from a non-accredited source. So I will share a view. When I was writing my little book about the Solar System I was confronted with a great many issues that, to me, had not as yet been answered. Mysteries intrigue me and this way it is possible to combine entertainment with some possibility of learning. Your first question is at the hub of the issue. My universe has all motion starting at the basic formation of the universe. Galaxies import motion to the objects born to them as a part of the motion of the galaxy. I want to be brief but I am confronted with a compromise as to how much information is required to make my comments intelligible and understandable with out going too far.

The galaxy is first for us imparting motion to all it contains. The Bible has a quaint way of stating this when ?god moved upon the waters? to enliven our solar system when up to then there was only dust.

How much mass is required to respond to the effect of the central mass of a galaxy? We are about two thirds of the way from the center to the edge of this galaxy. Logic suggests that as an unorganized collection of dust and gasses we could rotate as a diffuse unit, unrecognized collection of stuff for many rotations of the Galaxy. Why would it change? I think it slowly changed when the inertia of the solar stuff was attracted by the gravitation of the galaxy. This attraction would by nature effect the inner edge of this solar stuff and slowly drag that edge along at a faster rate then the central areas. As this motion was slowly shared by the inner parts of the solar stuff more and more began to rotate. As the rotation increased consolidation of the stuff increased and made it more attractive to the galaxy gravitation. The rest is well reasoned by the experts. The original motion of the galaxy fed the motion to the solar system and it remains the same to this day.

So why do the planets move as they do? Al matter with in this system moves at the whim of the sun. The single most massive object that controls everything with in its purview. For lack of a better description I think of the sun providing an envelope of gravitation, which itself moves, and takes along everything else. I think my math proves this. The sun moves and therefore so do the planets, its children.

The book is Surfing the Solar System. Poorly named. It was going to be the ?Solar Simplicity?. My follow up will use the latter.

It is all in fun.