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If the sun's gravity is strong enough to pull a comet from the kuiper belt why does it not pull the planets into it?

I was told that the sun's gravitational pull is so strong that it pulls comets in from the kuiper belt, but why does it not do the same to the planets? Since a comet is so small in size ,mass and density and so far out how is this possible? An old teacher of mine said it has to do with the planets speed and its own gravity, but doesn't a comet move at a faster speed than the planets? Does the fact that comets do not have a gravitational field play into this? Or am I being mislead? This may be a basic question but I have not found an answer that explains this. This question and a few others is making me think I need to take astrophysics in college . Thank you.


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  • Nov 15 2012: I understand that the kuiper belt has its own orbital structure and gravitational forces keep it there. I also understand that debris in that belt sometimes collide and objects are pushed out form there, causing it to "fall".
    I guess the question should have been what keeps us from being pulled into the sun?
    Is it centrifugal force? Or am I just over-thinking everything?

    Thank you John Smith and Lejan, like I said before it may be a simple question, but my science teacher cant explain it at all, he just says " that's just the way it is" then moves onto something completely unrelated

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