how did the planets get their positions
Posted on 2012-03-28
I'm not physics expert so I would appreciate an answer in simple terms please.
As i understand it the force of gravity on the planets is lower the further away you get. The mass of the planets has no real affect on the gravity as they are so small relative to the sun.
My understanding of planetary orbits is limited to a basic understanding on the cannonball model such that planets are orbiting when the force of gravity balances their momentum. So were the planets travelling at different speeds towards the sun and then 'stopped' (in terms of distance from the sun) at the distance from the sun where the gravity matched their momentum (from their speed) or is there more to it than that. I suppose the question is which came first: the speed of the planet or its distance from the sun.
Did their speed determine their distance from the sun or did their distance from the sun determine their speed? If it is the latter I don't understand how the planets got their positions in the first place.