了解宇宙是如何运行的（2010）

How the Universe Works S08E01

Part 5 Jan. 30, 2022, 2:57 p.m.

and things like that going on
at the time,
你可以看到这道闪光
and you can see
this flash of light.
那是什么鬼东西？
What the heck was that?
起初，闪光的原因是个谜
Narrator: At first, the cause
of the flash was a mystery.
事实证明，这实际上是一颗陨石
It turns out it was actually
a meteorite hitting
撞击了月球表面，虽然它很暗
the surface of the moon,
and because it was dark
但因为我们都在观察月全食
and because we were all looking
at it,
所以我们可以看到它
we could actually see it.
月球黑暗的表面
Narrator: The moon's dark
surface gave us a unique view
给了我们一个独特的视角
of what happens
when an asteroid strikes.
能够在黑暗的区域
What was so exciting
about being able
看到这种撞击月球的现象
to see this impact
on the moon in a dark area
令人兴奋，我们实际上可以观察到它产生的光
is that we could actually look
at the light that it produced
然后反向计算出
and then back-calculate
撞击物的确切大小
exactly what the size
of the impactor was.
我们计算出撞击的小行星
Narrator: We worked out that
the impacting asteroid
只有20英寸（约50厘米）宽
was just 20 inches wide.
它炸出的陨石坑有45英尺（约14米）宽
The crater it blew out
was 45 feet across.
这么小的东西怎么会有这么大的破坏力？
How can something so small
be so destructive?
最重要的两件事是它的速度
The two things that matter
the most are how fast it's going
和它的质量
and how massive is the thing.
质量越大，爆♥炸♥就越大
The more massive,
the bigger the boom,
速度越快，爆♥炸♥也越大
the faster the bigger the boom.
速度和重量是评估小行星破坏程度的
Speed and weight
are two very important factors
两个非常重要的因素
to assess how much damage
an asteroid will do.
就像拳击手一样——如果像我这样矮小的人
Just like a boxer --
if a tiny person like me
挥出一拳
were to swing a punch,
伤害会比重量级冠军小得多
it would do a lot less damage
than a heavyweight champion.
布洛克:小行星也是一样
Bullock:
Same thing with asteroids.
他们越大，打击就越大
The bigger they are,
the bigger the punch.
但是同样的东西也是快速的，对吧？
But the same thing
is fast, right?
如果我慢慢打你，你不会感到疼
If I hit you really slowly,
it's not gonna hurt.
我必须要像风一样出拳并击中
I have to really wind back
and pap.
这就是小行星的情况
That's what happens
with an asteroid.
小行星撞击的破坏力
Narrator: The damage from
an asteroid strike
取决于它的动能
is determined
by its kinetic energy.
动能取决于两件事——
Kinetic energy depends
on two things --
速度和重量
speed and weight.
两者中，速度是最重要的
Of the two, speed matters most.
如果质量翻倍，动能翻倍
If you double the mass,
you double the kinetic energy,
但如果速度翻倍
but if you double the velocity,
你会得到四倍的动能
you get four times
the kinetic energy.
三倍的速度，九倍的冲击能量
Three times the speed,
nine times the impact energy.
10倍的速度
10 times as fast,
它有100倍的能量
it has a hundred times
the energy,
所以速度是这里真正关键所在
so the velocity
is what's really critical here.
这颗月球小行星只有100磅重
Narrator: The lunar asteroid
weighed only 100 pounds,
但它以每小时38000英里（约61000公里）的速度运行
but it was traveling
at 38,000 miles an hour.
携带着巨大的动能，凿出了陨石坑
Carrying a huge kinetic energy,
which gouged out the crater.
对地球的影响也是同样的原理
It's the same principle
for impacts on earth.
五万年前，一颗150英尺高的小行星
50,000 years ago,
a 150-foot asteroid
撞击了现在的亚利桑那州
hit what is now arizona.
这次撞击产生了一个令人印象深刻的大坑
The impact blasted out
an impressive hole
现在被称为巴林杰陨石坑
now called barringer crater.
杜尔达:大约3/4英里（约1.2公里）宽
Durda: It's about
3/4 of a mile across,
500多英尺（150多米）深
over 500 feet deep.
你可以把华盛顿纪念碑
You could put
the washington monument
放在陨石坑的底部
in the bottom of the crater,
而纪念碑的顶部不会露出边缘多少
and the top of the monument
wouldn't quite clear the rim.
这是一个令人印象深刻的地洞
It's a pretty impressive hole
in the ground.
2016年，撞击专家凯茜·普列斯科(cathy plesko)
Narrator: In 2016,
impact specialist cathy plesko
访问了巴林杰陨石坑
visited barringer crater
亲眼目睹了质量和速度
to see firsthand
what mass and speed
对地球表面的影响
do to the surface of the earth.
♪
站在这样一个陨石坑的边缘真是令人惊叹
this is awe-inspiring to stand
on the rim of a crater like this
要知道挖掘这么多岩石
understanding
just how much energy
需要多少能量
it must have taken
to excavate this much rock.
小行星以每小时27000英里（43000多公里）的速度撞击地球
The asteroid came in
at about 27,000 miles an hour.
它撞击到表面
It comes slamming
into the surface
然后爆♥炸♥
and just explodes.
当冲击波产生时
Anywhere nearby here
附近任何地方都能看
would have seen winds
of thousands of miles an hour
到时速达数千英里的大风
as the shockwave came out.
♪
小行星撞击地球的巨大力量
narrator: The immense power
of an asteroid impact
来自于太空岩石
comes from the kinetic energy
向地表岩石传递的动能
being transferred from the space
rock into the surface rock.
这是一个非常剧烈的过程
It's an extremely
violent process,
从弹丸与表面接触的
and it starts with the moment
of contact
那一瞬间
of the projectile
with the surface itself.
普列斯科:它推进地壳
Plesko:
It pushes into the crust,
刚开始的时候，它就像戳一样
and at first,
it's just almost punching, like,
把你的拇指伸进面团里类似
sticking your thumb into dough.
洞只和物体一样宽
It's only about
as wide as the object is.
它是垂直向下的
It's going straight down in,
但是它遇到了来自地球表面的阻力
but then it's meeting resistance
from the surface of the earth.
所以它不断地挤压，挤压，挤压
And so it squishes,
squishes, squishes,
直到它没有动量，然后被它压缩得非常大的所有能量
until it runs out of momentum,
but then it's very compressed
都集中在一个非常小的空间里
and all of that energy is in
a very small space.
释放的时候，就会像炸♥弹♥一样引爆
As it releases,
it detonates like a bomb.
这就是陨石坑形成的原因
And that's what makes
the impact crater.
实验室中对小行星撞击的模拟
Narrator: Simulations of
an asteroid strike in the lab
以慢动作的形式揭示了撞击的过程
reveal the impact
in slow motion.
当高速的沙粒撞击表面时
As the high speed pellet
hits the surface,
沙粒向下压缩
the sand compresses downwards,
then rebounds.