Spot the difference
Space scientists are constantly scanning the skies to track known asteroids and identify new
ones - especially any that could become a threat to Earth.
Large telescopes photograph the sky and take a series of pictures at ten-minute intervals. Stars stay in the same place, but the movement of asteroids can be spotted by comparing these images.
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Stars appear as spots. The line is an asteroid as it moves across the sky.
Image: Iwan Williams |
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