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This is an image of the sun. 

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It was taken by an instrument called a coronagraph on NASA's STEREO mission.

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Our bright star is hidden beneath the black circle.

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The coronagraph blocks the sun with an occulting disk

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so it can observe the star's much-fainter outer atmosphere - the corona.

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This region shows background stars

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and ripples caused by diffracted light bending around the occulting disk.

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Scientists study these images to learn more about the activity in the corona.

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Solar wind flows outwards along these 'streamers'.

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Here is a coronal mass ejection, or CME, which is a huge magnetic eruption blasting from the sun.

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The CME flings solar particles at near-light speeds towards STEREO causing a 'snow' effect in the images.

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These powerful eruptions can dramatically affect the space environment,

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which, in turn, can affect satellites, astronauts, and Earth.

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