双语阅读：Black Holes黑洞（2）

摘要：After burning for billions of years, they get old and begin to run out of fuel. It still takes a long time for a star to die - it

Where do black holes come from?

Black holes are formed from some kinds of stars when they get old and die. Not all stars turn into black holes, only the biggest ones. Stars don't last forever.

After burning for billions of years, they get old and begin to run out of fuel. It still takes a long time for a star to die - it can be millions of years. First, the star swells up and turns red. Most stars then shrink and cool down into a small, heavy ball of ash - a dead star.

These dead stars are about the size of Earth, but much heavier - as heavy as the Sun.

黑洞从何而来？

黑洞是由某些类型的恒星衰老和死亡时形成的。不是所有的恒星都会变成黑洞，只有最大的恒星才会。星星不会永远存在。

在燃烧了数十亿年之后，恒星变老并开始耗尽燃料。一颗恒星的死亡需要很长的时间——可能是数百万年。首先，恒星膨胀并变红。然后，大多数恒星收缩并冷却成一个又小又重的灰球——一颗死星。

这些死去的恒星和地球差不多大，但比地球重得多——和太阳一样重。

When a really giant star starts to die, it doesn't just get bigger, it explodes. This massive explosion is called a supernova. It's very big and it only takes a couple of minutes. The star then collapses in on itself and shrinks to a tiny size. It becomes much smaller than a normal dead star. But as it has so much stuff crammed into it, it's also much, much heavier.

Finally, it becomes so tiny, it's just a very, very heavy dot in space. This is a black hole. It can take a million years for a giant star to change and become a black hole at the end of its life.

当一颗巨大的恒星开始死亡时，不仅会变大，还会爆炸。这种巨大的爆炸被称为超新星。它很大，只需要几分钟。然后恒星自身坍缩，缩小到极小的尺寸，变得比正常的死星小得多。但由于里面塞了太多的东西，它要重得多。