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Why Do Pictures of Stars From Space Telescopes Appear Point-Like Rather Than Round?

6 May 2018, 21:48 UTC
Why Do Pictures of Stars From Space Telescopes Appear Point-Like Rather Than Round?
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Question: Can you get a video image of a twinkling star in space? Also if stars do not twinkle in Space why are the pictures of them from space telescopes always pointy instead of round circles? — John
Answer: As you surmised, stars twinkle when viewed from the Earth’s surface because the motions of the Earth’s atmosphere cause the light from the star to shift as it passes through the Earth’s atmosphere. Pictures from space telescopes are not affected by the Earth’s atmosphere, so the stars appear point-like. Since stars are far away, they are in general not resolved in space telescope measurements. This is why pictures of stars appear point-like.
Jeff Mangum

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