I know at first glance this may seem like a simple question...but it just doesn't make sense to me unless there is a force I am unaware of. I realize tha gravity of the sun constantly wants to pull the earth(and all planets for that matter) into it's center. I also realize that the momentum of orbit (centrifugal force) is in the process of attempting to fling the earth out into space away from the sun. So how is it that each and every planet is in such complete balance on this infinitely small line of being either sucked into the sun or flung out into space? There are so many variables that would dictate one or the other...but not this PERFECT speed that keeps the earth from doing either. The only way I can understand this is if perhaps each planet had a certain frequency or vibration which dictated it's distance from the sun. Much like the force that keeps the protons circling around the nucleus without collapsing or flinging outward. Any thoughts on this would be welcome.