英语听力:自然百科 穿越银河系的旅行 Through Milky Way—10(在线收听) |
To understand how these calamities occur, astronomers need to catch a massive star in its death throes. Astronomers are like detectives. We have to figure out what's going on in the universe, sometimes based on a minimum number of clues. And in the case of most astronomers, the clues come from only the light.
Andy Howell knows that catching light from a supernova, it's all about timing.
Supernovae happen about once every 70 years in the galaxy on average, so about the human life time. So chances are, you are not gonna see one in your life time. In fact the last one in our galaxy that anybody saw was about 400 years ago. So it's been a long time, and you know, I study supernovae for a living. I couldn't do this if I had to just wait/ for one in our galaxy.
Thankfully, there is no shortage of galaxies.
So what we do is, we look at other galaxies, more distant galaxies. There are billions of galaxies out there.
This is a supernova that Andy and his colleagues were lucky enough to catch, an exploding star on the outskirts of a galaxy 55 million light years away. It briefly outshone the entire galaxy, the light to the billion suns distilled into one dying star.
It takes supernova/ light a million, or even a billion years to get here. They are millions of billions of light years away. But they only shine for about a month. So we have this little tiny window to study these things before that light has gone forever.
It's so critical that in the workshop Andy and his team are preparing to survey as much of the sky as possible.
We are building a network of telescopes so that we can study supernovae in greater numbers, in greater detail than we've ever been able to before. |
原文地址:http://www.tingroom.com/lesson/zrbaike/2011/260155.html |