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太阳死了我们还能活下去吗?

Can We Survive The Sun's Death?

太阳大概4.5亿岁了 像你一样 太阳也在变老
The sun is around 4.5 billion years old, and just like you and I, it’s aging. In just over
再过一百万年 太阳将会更热 它的热量将地球表面融化
a billion years, the sun will have expanded so much that the heat will begin to melt the
所以 地球上的生物会有办法避免这毁灭性的灾难吗?
earth’s surface. So, is there any way us Earthlings can avoid this detrimental event? Can we save
我们能在太阳的灭亡中幸免于难吗?
ourselves from the suns ultimate death?
当然 没有人在永远生存在地球上 因为我们没有找到长生的秘决
Sure, none of us will be here, assuming we don’t find the secret to everlasting life.
但在诞生后十亿年 太阳就会用完核心里的氢燃料
But, at the billion year mark, the sun will have used up the hydrogen fuel in its core,
这会迫使太阳的表面开始燃烧增加的辐射会使地球上所有的水分蒸发
forcing it to burn at its surface. The increased radiation will boil away all of the water
在地球上创造出一个跨越国界的沙漠 再过50亿年
on Earth creating an international desert. Flash forward about 5 billion years, and the
膨胀的太阳将会逐渐融化山脉 更甚的是 如果不是地球上的所有生命都灭绝
swelling sun will begin literally melting mountains, with most, if not all life on earth
大约75亿年后 膨胀的太阳——现在还是颗硕大的火球
now extinct. Around 7.5 billion years, the expanding sun – now a Red Giant – will engulf
会把地球完全吞没听起来十分残酷吧 那我们怎样才能不被吞噬?
the Earth entirely. Sounds bleak — so can we avoid this hot mess?
最佳的方法是:重力助推
It turns out; our best bet lies in something called “Gravity Assist”. A technique we’ve
这项技术已经被运用多年那就是不断向太阳系发射宇宙飞船
been using for years, only to launch space crafts throughout our solar system.
一旦飞船或卫星靠近某颗行星 它就会被行星的重力捕获
Anytime a spacecraft or satellite comes in close proximity to a planet, gravity grabs
如果飞船以完美的角度被捕获 它就能利用行星的速度
hold. And if the spacecraft arrives at the perfect angle, it’s able to use some of the
加速飞向太空深处 这种额外的能量
planets velocity to catapult it further into space. This ‘extra’ energy comes from the
来自于行星围绕太阳运行产生的能量但是 就像牛顿所说“每一个作用力
planet’s own energy of motion around the sun. But, as Newton famously said “To every action,
都有一个大小相等 方向相反的反作用力”既然飞行器利用了地球的重力
there is an equal and opposite reaction”. As the spacecraft uses the Earths gravity
才能加速返回地球那么行星也会轻微的减速
to speed up and move towards Earth, the planet will ever so slightly slow down and move towards
靠近航天飞船
the spacecraft.
当然 因为航天飞船的质量比行星小很多它离行星异常的远
Of course, the spacecraft’s mass is so small, comparatively, that it gets launched incredibly
而行星只会感受到一点点变化但是 假设我们增大了航天飞船的体型
far, while the planet experiences little change. But, if we were to increase the spacecraft’s
或是使用一颗小行星我们就能把地球从太阳的轨道上拽走
size — or use an asteroid — we could potentially move the Earth’s orbit away from the sun.
这需要数百万年的时光还要保证小行星距离地球足够近
This would take millions of years, and involve large objects coming just close enough to
而不会撞击地球嘿 我们还剩十亿年呢 别担心
not collide with Earth, but hey, we’ve got a billion year head start!
也许听起来很遥远 很虚幻但它真的发生了! 在2013年10月9日
It may seem far-fetched, but it’s already happening! On October 9th, 2013, Earth will
地球作为重力助推器 推送一架叫做Juno的航天飞船 飞往土星
be used to gravity assist a spacecraft called Juno, which is on its way to Jupiter. As Juno
Juno飞行在离我们559千米的地方并且将利用地球的重力
flies within 559 kilometers of us, it will use Earth’s gravity as a slingshot to boost
像弹弓一样把Juno推进到7.3千米/秒同时 地球也会移动一点点
its velocity by 7.3 km/s; Meanwhile, Earth will have been moved by a fraction. Juno will
之后 Juno会在2016年到达土星然后探寻其内部结构
later arrive at Jupiter, in 2016, where it will study the interior of the planet and
揭开壮观的太阳系神秘的面纱
help to unveil many new spectacular mysteries of our Solar System.
为了在数十亿年之内 让地球搬走
In order to move the Earth within our billion year timeline, we would need approximately
大约每过6千年 我们就要利用一颗小行星 大约质量为10的19次方千克
1 encounter every 6,000 years, using an object with a mass of approximately 10^19kg. That’s
那可是19个零! 这颗直径10万米的小行星 在过程中
19 zeros – somewhere around the size of a 100 km-wide asteroid. In between passes, the
小行星利用太阳这个“弹弓” 飞向土星 之后
asteroid would slingshot around the sun, fly out to Jupiter, and then be gravity assisted
利用重力助推飞回地球 这就像捕获的加长版
数百万年后
back to Earth – like one long version of catch between planets. Over millions of years, this
能从太阳系的运行轨道中 把地球逐渐拽远2.25亿千米
would move Earth to a comfortable 225 million kilometer orbit out from the sun.
不过即使可行 用现在的技术 也有一定的风险
And while it is feasible, even with today’s technology, it doesn’t come without risks.
首先 我们会失去月球 它总能给地球带来极端的天气形态
For one, we may lose the moon, which could ultimately create some extreme weather patterns.
更不用说 地球的旋转会增加 一天只剩下几个小时
Not to mention, the Earth’s spin may increase, making days only hours long. The surrounding
周围的行星 比如我们的新邻居火星它们的轨道会混乱
planets, like our new neighbor Mars, would likely have their own orbits destabilized.
另外…你知道 如果有意外 小行星可能会突然跌入地球
And…you know…the asteroid could come plummeting into Earth by accident.
或许 这些风险需要告知下一代人
But, perhaps these are the risks we need to take to give our descendants, the planet and
毕竟 地球和上面的一切生命 还会存在数十亿年
all life on it a few extra billion years.
有什么超级好奇的问题吗?在评论区提问 或者在脸书和
Got a burning question you want answered? Ask it in the comments, or on Facebook and
推特上提问 如果你还想了解Juno的知识 那就在我们的互动网站提问
Twitter. And if you want to learn more about Juno? Check out its awesome interactive website
网站已经给出 特别感谢NASA
we have linked in the description. Special thanks to NASA for inspiring and supporting
对这期节目的鼓励和支持 各位可以订阅更多每周科学视频
this episode, and subscribe for more weekly science videos.

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