了解宇宙是如何运行的（2010）

How the Universe Works S01E06

Part 4 April 18, 2021, 7:57 p.m.

and these monsters have
no solid surfaces at all.
迄今, 航♥天♥员新发现四百多颗行星
So far, astronomers have
discovered over 400 new planets
围绕其它遥远的太阳系运转
orbiting in far-off solar systems.
它们几乎全都是气态巨行星
Nearly all of them are
gigantic and made of gas.
我们的太阳系也有四颗气态巨行星
We have four of these so-called
gas giants in our own solar system.
木星、土星、天王星、海王星
Jupiter, Saturn, Uranus, Neptune.
各有一层稠似浓汤的厚厚大气层
Which all have these very
thick, very soupy atmospheres,
大量氢气、大量氦气、大量甲烷
lots of hydrogen, lots of
helium, lots of methane.
何以外行星气态? 内行星岩质?
Why are these outer four made of
gas when the inner ones are rocky?
关键全在位置
It all has to do with location.
距离太阳五亿哩的地方冰冷奇寒
Out here, 500 million miles
from the sun, it's very cold.
太阳系诞生之初, 哪里有尘
At the start of the solar
system, there was some dust,
但主要是气体和水, 凝结成冰粒
but mostly, gas and water,
frozen in ice grains.
那些巨行星初成时, 冷得有雪
Where the giant planets started to form,
it was cold enough to get solid snow.
估计会形成雪花
And we think we were able
to make ice snowflakes,
雪花结聚, 成为巨行星的核心
and these things were able to clump together
to form the cores of the giant planets.
巨行星因此变成那么巨大
And we think that's maybe why the
giant planets got to be so big.
当时冰与气体充斥, 核心越来越大
There was so much ice and
gas their cores grew huge,
十倍于地球
around 10 times larger than the Earth.
巨型核心产生强大引力
These giant cores
generated a lot of gravity.
拉力强横, 把周围的气体尽吸进去
They had so much pulling power, they
sucked in all the surrounding gas
积聚成几万哩深浓汤似的大气层
and built up thick, soupy atmospheres
tens of thousands of miles deep.
行星越大, 引力越强
The larger they got, the
more gravity they generated.
更多的尘与瓦砾给扯向行星
More and more dust and debris
got pulled in towards the planets,
遂成为孕育卫星的素材
and this became the building
blocks of their moons.
木星与土星各有六十多颗卫星
Jupiter and Saturn
have over 60 moons each.
气态行星还有另一个特色:
The gas planets have
another special feature:
行星环
rings.
土星那瑰丽的行星环虽是一枝独秀
Saturn is unique among the planets
in that has this gorgeous ring system.
其实木星、天王星与海王星也有环
It turns out Jupiter and Uranus and
Neptune, they have ring systems, as well.
只是薄弱稠零, 难以察觉
but they're really weak and pathetic
and extremely hard to detect.
但的而且确有环
But they are there.
四颗气态巨行星均有行星环
All four of the gas giants have rings,
但以土星的最为夺目
but Saturn's are the most obvious.
土星环远看如一只扁平圆碟
From a distance, Saturn's rings
look like a single flat disk.
其实土星环是由几千个小环聚成
However, they're actually
thousands of separate ringlets,
每一个才几哩宽
each only a few miles wide.
探测器卡西尼号♥掠过时
When the Cassini probe flew past,
探索到数十亿的冰块与宇宙瓦砾
it detected billions of
pieces of ice and cosmic rubble
在环内以高达五万哩的时速运转
orbiting inside the rings at speeds
of up to 50,000 miles an hour.
这些冰块与石块不时互相碰撞
These bits of ice and rock
constantly crash into each other.
有些形成小卫星, 有些撞个碎散
Some grow into tiny
moons, others smash apart.
但决不会发展成为大型卫星
But they never form into larger moons
因为早已被土星的巨大引力扯开
because Saturn's immense
gravity tears them apart.
行星环究竟如何形成
Scientists are only just
beginning to figure out
科学家也只是刚有头绪
how the rings formed in the first place.
理论是这样的:
The theory goes like this:
一颗彗星撞进一颗卫星
a comet smashed into a moon
把它撞出轨道, 于是更接近行星
and knocked it out of its
orbit and closer to the planet.
土星的引力把它撕成碎块
Saturn's gravity tore it to pieces.
瓦砾就此滞留在围绕行星的环内
And all of that debris got
trapped in rings around the planet
但气态巨行星的真正疑团
But the real mysteries of the
gas giants lie deep inside them,
埋在云下几万哩的行星深处
tens of thousands of
miles beneath the clouds.
哪里才是活动枢纽
This is where the real action is.
环境极端得要违背自然法则
It's a place so extreme it
challenges the laws of nature.
我们新发现的系外行星
Most of the new planets we're
finding around distant stars
以气态巨行星为主
are gas giants.
巨大得木星♥相♥形见绌, 变了侏儒
They're so huge they
make Jupiter look small.
但不论是系外的还是系内的
But what goes on inside
all gas giant planets,
气态巨行星的内在动态仍然是谜
both in our solar system and
way out there, is a mystery.
我们知道木星的大气层深四万哩
We know Jupiter's dense
atmosphere is 40,000 miles deep,
我们得见高速运转的气体带
and we can see high-speed bands of gas
在木星表面刮起剧烈风暴
creating violent storms
that rage across its surface.
但无从看穿风暴之下是甚么景象
But what we don't know is what's going
on deep inside, far beneath the storms.
为一探究竟
To find out,
太空总署派遣伽利略号♥探测木星
NASA launched the spacecraft Galileo
为期14年
on a 14-year mission to Jupiter.
…三、二、一
...three, two, one.
阿特兰蒂斯号♥与伽利略号♥点火升空
We have ignition and lift-off of
Atlantis and the Galileo spacecraft
飞赴木星
bound for Jupiter.
1995年12月7日
December 7, 1995.
伽利略号♥发射探测车
Galileo dropped a probe
以16万哩时速坠落木星的大气层内
that dove into Jupiter's
atmosphere at 160,000 miles an hour.
进入大气层后以降落伞减速
Parachutes slowed it down as it
dropped through the thick atmosphere.
探测车在云层里探测到闪电
It detected lightning in the clouds
还有时速450哩的强风
and winds of 450 miles an hour.
探测车地球传送数据仅58分钟
The probe transmitted data
back to Earth for 58 minutes.
大家追问落入大气层的探测车怎样
So people have asked me what happened
to the Galileo probe that we dropped in?
它没有撞中甚么
!t didn't hit anything.
只是一路深入木星里去
It just fell continually
into the Jupiter environment,
压力一路增强, 增强再增强
and the pressure increased
and increased and increased.
它下降时录得的压力是地球的23倍
As it descended, it recorded pressures
23 times greater than on Earth
温度超过300度
and temperatures of over 300 degrees.
深入气态巨行星之中
When you're in the
gas-giant environment
你在这氢气浓汤中越沉越深
and you go deeper and deeper
into this hydrogen soup
它没有固体表面
that has no solid surface,
却仍有惊人重量
it nevertheless can
have a tremendous weight
所以最后仍会把你压毁
And so eventually, you would be crushed
给覆盖物质的重量压毁
by the overlying weight of,
of the material that's there.
尽管探测车下坠仅124哩已给压毁
Even though the probe descended for
only 124 miles before it was crushed,
仍让科学家匆匆一瞥木星内部面貌
it gave scientists a glimpse
of Jupiter's interior.
只是行星的暗黑内心仍然神秘莫测
But the dark heart of the
planet still remains a mystery.
跟部分岩质行星一样
Like some rocky planets,
气态巨行星也有磁场
the gas giants have
a magnetic field, too.
但它们的磁场不能以常理度之
But these are off the charts.
木星磁场二万倍于地球磁场
Jupiter's magnetic field is 20,000
times more powerful than Earth's
强至延伸到四亿多哩外的土星
and so huge it extends all the way to
Saturn, more than 400 million miles away.
一如地球, 木星的磁场挡开太阳风
Like on Earth, the magnetic
field deflects the solar wind