2015-04-29 BBC:星光七纪元-29（在线收听） |
The supernovae that Alex photographs are hundreds of millions of light years away. The only reason that he can photograph them so distinctly is because there are such colossal explosions. And appreciating the power of a supernova's explosion has been the key to understanding the very composition of the universe. For centuries, scientists have known thta everything we see on earth is made of ninety two elements, and the stars are made of the same ones. We can see it in their starlight. Different elements give off different colours when they are heated, when they are energized. So if we look at a growing cloud of gas in the sky, we can determine what chemicl elements it's made from by seeing what colours it has. The calsium should produce a violet colour. Stronsuium, vow look at the stronsium go. sodium, a bit like the light of the flames. And finally I have got some copper here.
Look at the remnant of a supernova and you spot the signature colours of some elements. Modern scientists can reveal the full story by splitting the light with a prism to create a spectrum. |
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