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Wow! What a beautiful sunset.
哇！多么美丽的夕阳啊！
Enjoy it while it lasts, the sun won't be around forever, you know.
尽情欣赏吧，太阳不会永远存在的。
You mean, one day the sun will disappear?
你的意思是，有朝一日太阳会消失？
Not exactly disappear, but the sun will eventually burn out and die.
不是完全消失，太阳的能量最后会耗尽并枯竭。
Won't that make things really cold down here?
那样的话，地球就会变得很冷了。
Actually, there won't be any here, here.
实际上，那时地球就不存在了。
When the sun dies,the earth will be destroy too.
没有了太阳，地球也将毁灭。
Wow, hold on, start from the beginning.
等一下，你从头开始说。
Okay. Like all stars, the sun is basically a giant nuclear reactor that burns hydrogen to createenergy.
好的。像所有的行星一样，太阳从根本上说，是一个巨型核反应堆，通过燃烧氢气产生能量。
But like any reactor, the sun needs fuel to keep going.
但是，就像任一反应堆，太阳需要燃料来保持运作。
It's been going strong for around four-point-five billion years, and will probably keep burning for about five billion more.
它已经良好运作大约45亿年了，并且将会持续燃烧50亿年左右。
But then, the fuel will run out?
到那时，燃料就会耗尽。
Exactly. When it does, gravity will cause the sun's core to contract.
是的。当太阳能量耗尽，地心引力会使得太阳核心缩小。
When it contracts the corewill get hotter, which will heat up the sun's upper layers and make them expand.
缩小地同时温度变得更得高，这样就加剧了太阳外层的燃烧并使其膨胀。
The sun will then become what's called a red giant, and its radius will reach just past the orbit of Venus.
太阳就变成了所谓哦红巨星，它的半径将会达到以前金星的运行轨道。
Which is bad for us.
那样会对我们有害。
We'll be burned to a crisp.
我们会被烧成土豆片的。
That's sounds painful.
听起来很痛苦。
After a few billion years the core will begin to cool and expand.
数十亿年后太阳中心开始冷却并扩大。
The sun's upper layers will expand and lose material, and eventually the core will cool enough to become a white dwarf star,and finally a black dwarf.
太阳的上层也将扩大，失去物质重量，最后中心冷却到一定程度就成了白矮星，最终成黑矮星。
So, we're pretty much doomed.
那时，我们就注定要完蛋了。
Yes, but not for billions of years.
是的。但那是几十亿年以后的事了。
Who knows? By then, human's might been living on anotherplanet.
谁知道呢？到那时，人类也许已经生活在另一个星球上了。
