Why do stars appear to twinkle in the night sky?

National Space Centre expert Megan Whewell answers this question for us.

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The twinkling of stars in our night sky is down to the Earth’s atmosphere. As light from the stars travels towards Earth it can easily move in a straight line, but once it starts travelling through the Earth’s atmosphere it gets bounced around in different directions by the particles in the air.

For astronomers this twinkling can be a huge problem, especially when they’re trying to accurately image a particular star. The more the star twinkles, the blurrier the image will be.

If telescopes are launched into space then all images can be taken without Earth’s atmosphere in the way, but this is expensive. It is possible to use a system called ‘adaptive optics’, when tiny motors alter the surface of the telescope’s mirror to correct for this blur caused by the air.

Answered by Megan Whewell, Education Team Presenter for the National Space Centre.

Image courtesy of NASA

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