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Watch the expansion of the Cas A supernova remnant with your own eyes!

29 Aug 2019, 13:00 UTC
Watch the expansion of the Cas A supernova remnant with your own eyes!
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Wow. The Chandra X-ray Observatory just celebrated its 20th anniversary of being launched into space! It roared into orbit on board the Space Shuttle Columbia on July 23, 1999.

Chandra was a revolution in X-ray astronomy. This high-energy form of light can't penetrate Earth's atmosphere, so you have to launch telescopes into space to see it. On top of that, you can't easily focus X-rays, since they tend to pass right through mirrors. Awkward. So Chandra uses a set of nested, curved sheets of finely shaped metal set almost edge-on to the incoming X-rays. The photons hit the sheets at extremely low angle and graze off it like a rock skipping on water. In this way, the light is gently coaxed into moving in a different direction, so it can be focused this way.

Because of this it could see fainter objects giving off X-rays, as well as see more detail in them, too. In fact, after some testing in orbit, one of the first objects Chandra aimed its eye at was the remarkable supernova remnant Cassiopeia A (or Cas A for short). It was discovered decades ago as the brightest radio source in the constellation of Cassiopeia, but oddly ...

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