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comets are icy leftovers from the solar

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system's formation billions of years ago

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usually found in the cold distant

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reaches of the solar system some comets

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have orbits that periodically bring them

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closer to the sun

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once there the heat and radiation of the

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inner solar system vaporizes gas and

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dust from the comet and forms a tail

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coronal mass ejections or cmes are large

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clouds of magnetized gas ejected into

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space by the sun

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there are violent eruptions with masses

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upwards of a few billion tons that can

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travel out from the sun as fast as six

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million miles an hour

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on april 20th 2007 nasa's stereo

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satellite captured the first ever images

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of a collision between a comet and a cme

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combining the images into a movie we can

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actually watch as the comet known as

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comet enki collides with the passing cme

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pay attention to the way the cme causes

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a complete detachment of the comet's

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a preliminary analysis suggests that the

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tail was ripped away when magnetic

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fields bumped together in an explosive

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process called magnetic reconnection

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magnetic fields around the comet bumped

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into oppositely directed magnetic fields

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in the cme

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though our planet doesn't have a tail

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a similar process actually takes place

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when a cme collides with earth's

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magnetosphere

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shining beautifully in the polar sky the