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Ask a Scientist: Speed of Comets - Transcript

Hi NASA, I'm Jalen. I'm in the 4th grade and my question is how do comets gain speed as they move along through space?

Steve Chesley, EPOXI, NASA/JPL: Well, as a comet comes in closer to the sun, it's literally falling under the force of gravity and accelerating, just as a brick dropped from a tall building speeds as it falls to the Earth. The comet is falling to the sun and as it gets close, it most of the time will miss the sun, but not always and then sweep around the back side and shoot out again to the outer solar system where just like a pop-up fly in baseball it will fly up high and fall back down to the sun again and do this over and over again.

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