
Dark Matter
In Our Time: Science
00:00
The Halo of Dark Matter
In the 1970s astronomers started looking at galaxy clusters using X-ray telescopes. And what they found was there's actually a lot more hot gas in the cluster than there are galaxies about a factor of 10 roughly. So that just added some more information about what the dark matter had to be. But still that's not all of the missing mass. There's still five or six times as much stuff in the galaxy cluster on the whole as there is this hot gas.
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