了解宇宙是如何运行的（2010）

How the Universe Works S08E01

Part 9 Jan. 30, 2022, 2:57 p.m.

Narrator: It was like a giant
cosmic game of pool --
行星撞行星
planet smashing into planet.
这次猛烈碰撞的残余物
The leftovers
from this violence
在火星和木星之间形成了一个垃圾环
formed a ring of junk
between mars and jupiter.
现在我们称之为垃圾小行星
And now we call
that junk asteroids.
它们基本上就是太阳系形成时
They're just basically
rubble left over
留下的碎石
from the formation
of the solar system.
岩石残余物变成了c型
Narrator: Rocky leftovers
became c-type
或球粒陨石小行星
or chondrite asteroids.
它们的密度相当大，所以大的可以穿透大气层
They're quite dense, so big ones
can punch through the atmosphere
并撞击地面
and hit the ground.
雷达发现了一种更罕见的小行星
Radar reveals
a rarer type of asteroid.
其中一些非常突出，因为它们的密度
Some of them really stand out
because their density
比其他小行星要高得多
is so much higher than the rest
of the other asteroids.
这些小行星是m型或金属
Narrator: These asteroids
are m-type or metal.
由于它们的质量很大
Because their mass is great,
它们在撞击时携带了更多的动能
they carry more kinetic energy
during a strike.
到目前为止，最糟糕的是这个铁陨石
By far, the worst one
is this iron meteorite.
这个真的很重，所以肯定是不同的——
This is really heavy,
so the difference --
如果你被这个击中
if you were being hit
by this,
那就相当于被石头击中
it would be the difference
between being hit by a rock
和被金属锤击中的区别
and being hit
by a metal hammer.
我们认为巴林杰
Narrator: We think that both
the barringer
和 k-pg 恐龙杀手
and the k-pg dinosaur killer
都是由金属小行星造成的
were caused by metal asteroids.
但还有另一种更神秘的类型
But there's another more
mysterious type
漂浮在太空中
floating through space.
♪
2018年12月
December 2018,
美国宇航局的航♥天♥器奥西里斯-雷克斯
nasa's spacecraft osiris-rex
approached
接近近地小行星“贝努”
the near earth asteroid bennu.
沃尔什:随着时间的推移，它离开了主小行星带
Walsh: Over time, it drifted out
of the main asteroid belt,
进入了太阳系内部
made its way into
the inner solar system,
直到它成为了一颗近地小行星
until it became
a near earth asteroid,
我们的宇宙飞船可以访问到它
accessible for our spacecraft
to go and visit.
奥西里斯将相机对准贝努
Narrator: Osiris trained
its camera on bennu.
♪
“贝努”号♥抵达小行星表面后
one of the biggest surprises
on arrival of bennu
最令人惊讶的地方之一是其表面有大量的巨石
was the large number of
large boulders on its surface.
贝努上到处都是巨大的石块
Bennu is really littered
with huge boulders
中等大小的石块
and littered
with medium-sized boulders
还有小石块
and littered
with small boulders.
贝努不是一块坚硬的岩石
Narrator: Bennu is not
a solid lump of rock.
它由数千块岩石组成
It's made up of thousands
of bits of rock
形成了我们所说的碎石堆
forming what we call
a rubble pile.
这些小行星并不是巨大的、单一的
These asteroids aren't big,
singular, spherical balls
球形的岩石
of rock,
它们实际上是成堆的碎石
but rather they're literally
piles of rubble.
它们是来自另一颗小行星的
They're all sorts
of pieces and fragments
各种各样的沙砾和碎石
from another asteroid
that had previously
它们之前被破坏过，现在又重新聚集在一起
been disrupted
that have all come back together
形成了一堆由自身引力
and formed literally a pile
of rocks held together
聚集在一起的岩石
by their own gravity.
我们认为碎石小行星是由小行星带内部
Narrator: We think rubble piles
formed from collisions
碰撞形成的碎石堆，每次撞击都会炸成碎片
inside the asteroid belt
each impact blasted bits off.
然后，随着时间的推移，它们又聚在一起
Then, over time,
they came back together
形成了一个松散的岩石堆
to form a loose pile of rocks.
杜尔达:想象一下，把一辆装满沙砾和碎石的
Durda: Imagine taking
a big cosmic dump truck
宇宙自卸卡车
full of gravel and rubble
扔到太空中
and dumping it
out there in the space
通过微弱的引力把它们粘在一起
and letting gravity
weakly hold it together.
当科学家们深入探索贝努时
Narrator: When scientists probe
deeper into bennu,
他们发现了另一个惊喜
they found another surprise.
到处都是洞，像瑞士奶酪一样
It's full of holes,
like swiss cheese.
如果你能切开其中一颗小行星
If you could slice open
one of these asteroids,
你会看到里面有很多空隙
you'd see there are
a lot of voids.
事实上，我们看到的60%都是空洞的空间
In fact, 60% of what we're
looking at is a void space,
所以它们实际上是蓬松的
so they're actually
really fluffy.
所以即使它们是由岩石组成的
So even though
they're made of rocks,
它们也像是岩石的绒毛
they're sort of
the lint of rocks.
贝努帮助我们理解阿波菲斯
Narrator: Bennu helps us
understand apophis.
雷达数据显示，阿波菲斯也是一堆碎石
Radar data shows that
apophis is also a rubble pile.
如果你观察阿波菲斯，我们真的想知道
If you look at apophis,
we really want to know
它的轨道在未来会如何演变
how its orbit will evolve
in the future.
我们在贝努所了解到的类似大小的碎石堆小行星
What we learn at bennu
about similar-sized
可能有助于我们了解
rubble-pile asteroids
might help us understand
像阿波菲斯这样的小行星的未来
the future of an asteroid
like apophis.
那么，如果被称为阿波菲斯的碎石堆
Narrator: So what would happen
if the rubble pile
撞上地球会发生什么呢？
called apophis hits earth?
杜尔达:你可能仍然不想被它撞上
Durda: You probably don't want
that to hit you still,
但可以肯定的是
but it definitely
makes it a lot weaker
它比坚硬的岩石
than something like a solid rock
或一大块镍铁之类的东西要弱得多
or even more, a chunk
of nickel iron metal.
它的结构会减少它的威胁吗？
Narrator: Does its composition
make it any less of a threat?
其实像阿波菲斯这样的碎石堆尤其令人不安
A rubble pile like apophis
is especially unnerving
因为我们不知道，当它与大气相互作用时会发生什么
because we don't know, when it
interacts with the atmosphere,
如果它是一个固体
if it's gonna stay
as one solid piece,
它会不会破裂
will it break up.
但当这些碎石堆开始与行星♥相♥互作用时
When these rubble piles
start interacting with planets,
只要它们飞到行星附近
if they fly near a planet,
they can get pulled apart
就会被扯成碎片
into all of their little pieces.
或者，如果它们进入一个行星的大气层
Or if they enter
the atmosphere of a planet
并撞击其表面，它们可能会
to impact the surface, they
might slowly get pulled apart
在进入大气层时
as they enter the atmosphere
慢慢地被拉开，最终形成
and end up being