了解宇宙是如何运行的（2010）

How the Universe Works S05E02

Part 6 April 18, 2021, 7:46 p.m.

from a passing neighbor.
想象一下这个很酷的场景
Imagine this cool scenario.
你得到了一颗系外行星
You've got an alien star.
在恒星周围形成了一颗行星
And around that star forms a planet.
这就是9号♥行星
This is planet 9.
太阳呼啸而过
And here comes the sun whizzing by.
离如此之近，以至于它在进入银河系的过程中
The sun gets so close that it steals planet 9
偷走了9号♥行星
on its way out into the galaxy.
听起来像科幻小说
It sounds like science fiction.
但我们的太阳可能已经有了犯罪记录
But our sun may already have a criminal record.
有一些证据表明，我们太阳系中的彗星
There's some evidence that the comets in our solar system
可能并非起源于我们的太阳系
may not have started in our solar system.
我们可能从其他恒星偷走了彗星
We may have stolen comets from other stars.
如果是这样的话
If that's the case,
那么认为一颗恒星围绕另一颗恒星
it's not totally outrageous
并以某种方式让邻居的行星进入了我们的太阳系
to think that a planet that formed around another star
并成为我们家庭的一部分
somehow made its way into our solar system
也就不足为奇了
and became part of our family.
但如果9号♥行星真的来自另一颗恒星
But if planet 9 really did come from another star,
我们如何确定它是外星来客呢？
how will we know for sure that it's an alien visitor?
我们想做的本质上是
What we'd like to do is essentially
对九号♥行星进行DNA测试
a DNA test on planet 9,
通过它的一些表面
scoop up some of its surface
寻找那些我们可以确定不可能
and look for material that we absolutely know
在太阳周围形成的物质
couldn't have formed around our sun,
因为我们在太阳系的其他任何地方都看不到这种物质
because we don't see it anywhere else in our solar system.
我们甚至可能需要发射一个探测器
We may even have to send a probe there
去仔细观察它
to really get a good look at it
找出它的化学成分
and find out what its chemical composition is,
以及我们能找到的关于它轨道的一切
exactly everything we can find out about its orbit.
这样，我们就能看到
And, that way, we might be able to see
是否有任何“指纹”性的
if there are any sort of fingerprints,
确凿的证据能清楚地说明
smoking-gun pieces of evidence
这是在这里形成的
that'll say clearly this formed here
还是在那里形成的
or it formed out there.
不幸的是，在我们向9号♥行星发射探测器之前
Unfortunately, before we can launch a probe to planet 9,
我们必须先找到它
we first have to find it.
迈克·布朗(Mike brown)等天文学家
Astronomers like Mike brown
利用数学方法缩小了区域范围
have made the challenge a little easier,
使这一挑战变得简单了一些
using math to narrow down the zone.
我们现在知道的是9号♥行星
What we know right now is that planet 9
就在天空中像这样的一片区域中
is in a swath of the sky that goes about like this.
大概有这么大它像这样穿过
It's about this big. It goes across like this.
但我们认为我们甚至知道了一点
But we think we even know a little bit better.
我们已经确定了，或者至少是稍微限制了它的位置
We've pinpointed, or at least slightly constrained
大概有这么大的一片天空
where it is, to a patch of sky that's about this big.
还有很多天空要看
It's still a lot of sky to look at.
但这比观察整个天空要少得多
But it's a lot less than having to look at the whole sky.
麦克标记的那片天空靠近猎户座
Mike's patch of sky is close to the constellation Orion.
他打算等到秋天
He's going to wait until fall,
猎户座在天空中最高的时候
when Orion is highest in the sky,
用位于夏威夷斯巴鲁的
to search for planet 9
红外望远镜寻找第九行星
using the Subaru infrared telescope on Hawaii.
这架望远镜经过微调
The telescope is fine-tuned
可以在太空深处寒冷的背景下
to pick out the faint heat signature
分辨出遥远物体
of distant objects
微弱的热信♥号♥♥
against the cold backdrop of deep space.
9号♥行星可能冻结了
Planet 9 may be frozen.
但它会比太空暖和一些
But it will be warmer than space.
这种微小的温差
And that tiny difference in temperature
正是这台望远镜所需要的
is all this incredible telescope needs.
我们想要看到天空中同一区域
We want to see two pictures taken
相隔几周拍摄的两张照片
of the same area of the sky a few weeks apart.
星星不会移♥动♥
The stars don't move.
但是你看这个，当你来闪回图片的时候
But you see this one, little thing going, "boop, boop, boop,"
有个小东西在发出“噗噗噗”的声音
as you flash the pictures back and forth.
这就是当你有一个物体在恒星的背景下
That's what happens when you have an object
围绕太阳运动时
moving around the sun
所发生的事情
against the background of stars.
冥王星就是这样被发现的
That's how pluto was discovered.
如果9号♥行星存在的话我们就是这样找到它
That's how we're gonna find planet 9 if it exists.
要找到第九颗行星
It could take years to find planet 9.
可能需要数年时间
But when we do spot it,
如果我们发现它，科学家就能分♥析♥它的光
scientists will be able to analyze its light.
在那微弱的光中
And hidden within that faint glow
可能隐藏着岩石、冰或气体的
could be the chemical signature
化学特征
for rock, ice, or gas.
如果是这样
If it is, planet 9's identity
九号♥行星的身份将最终揭晓
will finally be revealed.
在那之后会发生什么是一个谜
What lies in store beyond that is a mystery.
但也许最令人兴奋的前景是
But perhaps the most exciting prospect
9号♥行星可能是卫星家族的家园
is planet 9 could be home to a family of moons.
在这些卫星中，也许会有一颗
And it's just possible one of these moons
可能在距离太阳1000亿英里的地方
could provide a home for life
为生命提供家园
100 billion miles from the sun.
我们在宇宙中是孤独的吗？
Are we alone in the universe?
几十年来，科学家们一直在寻找
For decades, scientists have scoured
离我们最近的行星邻居
our closest planetary neighbor
寻找外星生命的迹象
for signs of extraterrestrial life.
但到目前为止，还没有找到任何线索
But so far, not a trace has been found.
有没有可能我们的目标错了？
is it possible we're targeting the wrong planet?
如果9号♥行星是真实存在的
If planet 9 is real,
那么它就位于太阳系的冰冷边缘
it sits on the icy outer limits of the solar system.
但即使在这里，距离太阳1000亿英里的地方
But even here, 100 billion miles from the sun,
生命也有可能在其卫星深处
it's just possible that life could thrive
而非地球上
not on the planet itself,
茁壮成长
but deep inside its moons.
历史上，我们一直认为卫星
Historically, we've always thought of moons
就是这些微不足道的地方
as being these little, insignificant places.
但不可思议的是
But the incredible thing is they may be
它们可能是发现生命最好的地方
the best places to find life.
仅在我们的太阳系中
In our solar system alone,
行星的卫星上存在生命的可能性
there may be far more chances for life on moons of planets
就比行星本身存在生命的可能性大得多
than there are on planets themselves.
卫星让天体生物学家兴奋
Moons excite astrobiologists
因为无论它们离太阳有多远
because they can sometimes support liquid water,
它们有时都能支持液态水的存在
no matter how far they sit from the sun.
关键是潮汐加热
The key is something called tidal heating.
在椭圆轨道上的
Moons on elliptical orbits get squashed
卫星会被其母行星的引力不断挤压
and squeezed by the gravity of their parent planet.
这会产生热量，融化冰
This generates heat and melts ice
形成地下液态水海洋
to form underground oceans of liquid water,
这是我们所知道的生命的关键成分
the key ingredient for life as we know it.
如果9号♥行星像科学家预测的那样大
If planet 9 is as big as scientists predict,
它可能有多个卫星
it could have multiple moons.
也许其中一颗卫星上
And maybe one of those moons
有温暖的咸海
could have warm, salty oceans
能适合简单的生活
primed for simple life.
所以，如果有九号♥行星
So, if you have planet 9,
它有冰冷的卫星，这些冰冷的卫星
and it's got icy moons, and these icy moons
在正确的轨道上
are on the right kinds of orbits,
热量可能来自内部，而不是外部
the heat could be coming from within, not without.
所以太阳基本上不重要
And so the sun basically doesn't matter.
地表下可能有液态水，这些液态水
You could have liquid water below the surface
是由内部地质条件加热而成的
that's heated from the internal geology.
你可能会看到像我们看到
You could have geysers of water
在土星和木星周围的卫星上
like what we see coming off of moons
喷出的间歇泉
around saturn and Jupiter.
你可以在9号♥行星上看到它
You could have that all the way out there at planet 9.
想象一下9号♥行星上有一组巨大的卫星
Imagine planet 9 with a system of giant moons.
最近的卫星被9号♥行星的巨大引力