了解宇宙是如何运行的（2010）

How the Universe Works S06E08

Part 3 Dec. 22, 2021, 7:23 p.m.

你不会期望在这么小的行星上
You don't expect to get
a core that large
有这么大的核心
in a planet that small.
就好像水星在某个地方失去了一些地幔
It's almost as if Mercury lost
some of its mantle somewhere.
我是说，也许它把它落在沙发后面了
I mean, maybe it left it
behind the couch.
谁知道呢？但现在它消失了
Who knows?
But it's gone now.
但是这些物质是如何消失的呢？
But how can this
material just vanish?
水星可能现在是这个样子
Mercury could be
the way it is now
但它一开始是一颗大得多的行星
because it started as
a much larger planet
后来发生了一些事情，剥去了它的顶层
and then something happened to
strip away the top layer of it,
我们知道如何在行星范围内做到这一点的
and the only way
we know how to do that
唯一方法就是行星撞击
on a planetary scale is
with planetary impacts.
想象一下还在太阳系形成时的早期
Picture the early solar system
when Mercury is still forming.
水星与我们现在所了解的小世界完全不同
It's completely different from
the little world we know now.
它的质量是原来的四倍，火星的两倍
Up to four times more massive,
twice the mass of Mars,
但它的轨道却是一个射击场
but it orbits
in a shooting gallery.
撞击是不可避免的，不久之后
Impacts are inevitable,
and before long,
一个月球大小的天体在一次巨大的撞击中
an object the size of our moon
smashes into Mercury
撞向了水星
in a giant impact event.
这是世界末日
This is apocalyptic.
这是你能做的最汗流浃背的噩梦了
This is the sweatiest
nightmare you can have.
事件导致重塑了整个星球
You're resurfacing
an entire planet.
能量是巨大的
The energies are vast.
其中一次巨大的撞击可能会
One of these giant impacts
probably would have remelted it
让星球重新熔化
all the way through.
结束之后剩下的东西
What's going to remain
after it's done
与开始时的样子
is completely different
已经完全不同
than what started
in the first place.
很难夸大这些事件的影响有多大
It's hard to overstate just
how impactful these events are.
大量的水星地幔被抛入太空
Huge chunks of Mercury's mantle
are flung into space.
结果呢？
The result?
现在它的三分之二的质量是由它的核心组成的
Two-thirds of its mass
are now made up by its core,
但它的其余部分去了哪里？
but where did the rest of it go?
数十亿年前，有一颗
Billions of years ago,
there was a planet
我们永远不会知道的行星
that we will never know,
一颗在水星形成时就被摧毁的行星
a planet that was destroyed when
the current Mercury was formed.
有没有可能其中的一部分还在外面？
Is it possible that some of it
may still be out there?
丢失的地幔碎片可能仍然存在于
The lost mantle debris
could still exist
太阳系的最内部
in the innermost solar system.
科学家们称这些假想的物体为祝融小行星
Scientists call these
hypothetical objects vulcanoids.
祝融小行星对于
Vulcanoids can be very valuable
了解水星的形成非常有价值
for understanding
the formation of Mercury
因为其中一些祝融小行星
because some of these vulcanoids
可能是水星缺失的地幔的碎片
may be pieces of
Mercury's missing mantle.
但为了生存
But in order to survive,
这些祝融小行星必须
these vulcanoids
would have to orbit
在引力的绳索上运行
on a gravitational tightrope.
你懂的，就像这个棉花糖一样
You know, like this marshmallow,
vulcanoids exist
祝融小行星存在于太阳系中一个不稳定的位置
in kind of a precarious
position in the solar system,
如果离火太近，或者离太阳太近
a little too close to the fire,
a little too close to the Sun,
这些物体就会蒸发
those objects actually
would vaporize away,
就像这样
kind of like that.
如果你的轨道离太阳太远
If you orbit too far
from the Sun,
你就会离水星太近
you're going to approach
too closely to Mercury
会遇到引力碰撞
and have gravitational
encounters,
可能会被甩出太阳系
maybe get flung out of the solar
system or maybe just impact
或者可能会撞到水星本身，然后被吃掉
Mercury itself
and get eaten, if you will.
但这两个极端之间
But in-between
those two extremes,
在距离太阳合适的地方
at just the right
distance from the Sun,
比水星离太阳近一点
a little closer
to the Sun than Mercury,
但不是那么近,于是就有了“油炸”
but not so close
that you get fried,
这是一个祝融小行星区域
is this vulcanoid region where
objects in orbit around the Sun
在这个区域中，围绕太阳运行的物体
could remain
gravitationally stable
可以在整个太阳系中保持引力稳定
over the entire age
of the solar system.
那里是寻找类似小行星的
That's the place to look
for this potential population
潜在天体的地方
of little asteroid-like objects.
在整个银河系中，我们发现许多天体都可以在恒星周围的内部区域存在
大多数恒星系都有很多的行星靠近恒星，甚至比水星更近
出于某种原因，我们内部的太阳系出人意料地安静
此外，发现水星碎片将刷新我们在整个太阳系中发现的东西
我们发现的碎片，是行星形成的化石，它们散布在整个太阳系
在火星和木星之间，存在有大量的小行星
我们环顾木星和土星的轨道，我们发现在木星附近有特洛伊小行星在运行
我们观察海王星外♥围♥的地方，可以看到整个柯伊伯带的小行星运行的轨道
当你观察我们的太阳系时，有几个空隙
每当我们看到行星间的空隙，我们就会看到碎片
而太阳和水星之间也有空隙
那么那里有碎片吗？
这些碎片的存在肯定是有意义的
当我第一次听说祝融小行星时，我真的为这个想法而激动
这很酷，因为它可能是太阳系的一部分，就在我们的面前
我的意思是，这真的离太阳太近了
因为我们还没有发现，基本上我们对太阳这一区域一无所知
所以这一切，我都喜欢
太阳系中一个全新的、看不见的区域
其中可能含有水星丢失的地幔的残余物
我们知道他们应该在哪
We know where they should be,
但有个问题
but there's a problem.
你可能想知道
You may wonder why haven't
如果这些祝融小行星真的存在，为什么我们看不到它们？
we seen these vulcanoids
if they actually exist?
如果它们真的在轨道上运行，为什么我们不去寻找它们呢？
If they're actually orbiting,
why don't we just look for them?
这是因为它们离太阳太近了
Well, it's because they're
really close to the Sun.
不同于小行星或柯伊伯带天体
Unlike the asteroids
or the Kuiper belt objects
从我们所在地球的角度来看
where we're looking out
away from the Sun
我们是向远离太阳地方观察
from our perspective
here on the Earth,
我们搜寻的是黑暗的夜空
we're looking out into
the dark nighttime sky,
然而祝融小行星的情况却相反，我寻找的这些东西
in the case of the vulcanoids,
we're looking for something
非常、非常接近太阳
very, very close to the Sun,
接近真正的光源
in close to that really
brilliant light source.
我们的太阳直径大约90万英里
Our sun is around
900,000 miles across.
水星只有3000英里
Mercury is just 3,000.
当我们的望远镜看到水星从太阳前面经过时
When our telescopes see Mercury
passing in front of the Sun,
它就像一个小针♥刺♥
it's little more
than a pinprick.
而对于我们所要寻找的祝融小行星
With vulcanoids, we're searching
for something
是比水星小几千倍的星体
thousands of times
smaller than Mercury.
如果祝融小行星存在，它们将在一个盲点上运行
If vulcanoids exist,
they orbit in a blind spot,
但科学家将继续寻找它们
but scientists will keep
searching for them
因为它们可能是水星失去的
because they could be
the last surviving remnants