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Sep19-10, 02:38 PM
P: 775
Quote Quote by coltseaversuk View Post
Ok I'm a bit closer to understanding it (I'm an Electrical Engineer not a Physicist). I've read the inertia article, so the planets are in inertial motion now yes? So did something have to accelerate them initially?
They formed from smaller particles already in orbit around the Sun, so nothing accelerated the planets as such. How did the stuff end up in orbit to start with, you may wonder? Conservation of angular momentum meant not all the original collapsing cloud of gas and dust could directly collapse into a star, so the rest ended up in orbit around most of it which had collapsed.