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The Sun is the most important star in our galaxy, and at some point, it's going to die.
太阳是我们银河系中最重要的恒星，但在某个时刻，它将死亡。
When that happens, it'll turn into a red giant, getting so big it'll swallow Mars, Mercury, and quite possibly vaporize our own planet.
当这种情况发生时，它将变成一颗红巨星，如此巨大的它将吞噬火星、水星，而且很可能将地球蒸发。
Don't panic yet, we've got a billion years to prepare before the big red comes.
不要惊慌，在这个大红星球到来之前，我们还有十亿年的时间可以准备。
Stars have a life cycle just like us: they are born, they live, and then they die.
恒星和我们一样，有生命周期：它们出生，生长，然后死亡。
During their lives, stars need to have a strong core,
在它们的一生中，恒星需要有一个坚强的内核，
one that can fuse hydrogen into helium to make nuclear fusion.
一种能把氢熔化为氦，从而进行核聚变的内核。
Stars will work their cores for billions of years.
依靠这个内核，恒星将可运行亿万年之久。
But eventually, they'll run out of hydrogen for their fusion process.
但最终，它们的聚变过程将耗尽氢气。
When that happens, the star can't hold up against gravity and its core will start to collapse.
当这种情况发生时，恒星不能承受重力，它的内核将开始崩塌。
The core will get smaller and denser, while its outer shell expands and cools, giving a distinctive red hue.
其内核将变得越来越小，密度越来越大，而它的外壳会膨胀冷却，使其呈现一种独特的红色。
Red giants are HUGE, reaching sizes of or 62 million to 621 million miles.
红巨星非常巨大，其直径可达0.62亿至6.21亿英里。
That's nearly 1,000 times the size of the sun.
大小几乎是太阳的100倍。
So when our sun turns into a red giant, life as we know it will cease to exist.
所以当我们的太阳变成红巨星时，正如我们所知，它的生命也将停止。
But there is an upside to this.
但也有一个好处。
When stars morph into red giants, they change their habitable zone.
当恒星变成红巨星时，它们改变了它们的居住环境。
The habitable zone is a region with the right conditions for life.
这样的居住区有着宜居的条件。
So as the Sun gets larger and redder, it's warmth will extend to the outer reaches of our solar system.
所以当太阳越来越红，它的温暖会延伸到太阳系的外围。
Making it possible for life to begin on a whole new planet.
这样，生命可能在一个全新的星球诞生。
