了解宇宙是如何运行的（2010）

How the Universe Works S01E08

Part 1 April 18, 2021, 7:58 p.m.

宇宙万物似乎都环绕某些东西运行
In the universe, everything
seems to orbit something.
行星环绕恒星、卫星环绕行星
Planets orbit stars
and moons orbit planets.
有些卫星有火山活动, 但喷的是冰
Some moons are volcanic,
but the volcanoes are ice.
另一些卫星满布大海洋
Others are awash with great oceans.
在我们的银河系
There may be more habitable
moons in our galaxy
可住人的卫星或多于可住人的行星
than there are habitable planets.
卫星可解开太阳系一些未知的奥秘
Moons tell the unknown
stories of our solar system
让我们明白星系的运作
and show us how it all works.
解读宇宙
How the Universe Works
第1季第8集：卫星
Moons
我们的太阳系只有8颗行星
In our own solar system,
there are just eight planets.
但其中6颗都有卫星环绕运行
But orbiting six of
those planets are moons.
很多很多的卫星, 总数超过300
Lots and lots of moons,
more than 300 of them.
每一颗各有特色
Each one is different.
每一颗自成一个世界
Each one a world all its own.
我们望出太阳系, 可见到大批行星
Well, when we look out on our solar
system, we see a lot of planets.
不过卫星的数目更多
But even more than planets we see moons.
也比它们所环绕的行星
And in many ways,
they're more interesting
更有趣味
than the planets that they go around.
有些卫星没有空气, 像月球般死寂
We have moons that are airless
and apparently dead, like ours.
但外太阳系有些卫星藏有海洋
Then, out in the outer solar system,
we have moons with oceans inside them
有些卫星有大气层
and moons with atmospheres around them.
我喜欢卫星, 行星送给你好了
I'm for moons. You can keep the planets.
太阳系中最灿烂的爆发…
The biggest eruptions...
最冷的气温…
the coldest temperatures...
最大的海洋
and the largest oceans
in the solar system...
都集中在卫星
they're all on moons.
有些卫星满布冰♥火♥山
There are moons with ice volcanoes.
有些卫星
There are moons
有甲烷湖、甲烷雨
with lakes of methane
and methane rainfall,
甲烷烟雾、甲烷云
smog, clouds.
有些火山不断爆发, 表面历久常新
Moons that are so volcanically active
that they keep remaking their surface.
有些会把各种烟尘, 喷出外层空间
Moons with all kinds of
plumes shooting off into space.
环境千变万化, 超乎我们的想象
Really, a much wider range of environments
than we ever could have imagined
我向群众以至科学界同事介绍…
Often, when I'm describing to general
public or even to my fellow scientists,
土星和木星的卫星时
these moons of Saturn and Jupiter,
把它们称为「世界」
I call them worlds.
它们真的是复杂而神秘的世界
Because they really do have the
complexity and mystery of a whole world.
木星和土星各有60多颗卫星
Jupiter and Saturn
have over 60 moons each.
两颗巨大气体行星和它们的卫星
These giant gas planets and their moons
好像自成一个袖珍太阳系
are like mini solar systems.
而每颗卫星各有不同特色
And each moon has a
distinct personality.
土卫八是颗黑白两色的卫星
lapetus, a two-toned
moon in black and white.
土卫六有浓密、橙色的大气层
Titan, with a dense orange atmosphere.
冰封的土卫二有冰喷泉
And icy Enceladus blasting ice geysers
喷入太空200英里
200 miles into space.
每颗卫星自成一格
Each moon is unique,
但也有一个共通点:
but they all have one thing in common:
它们都是由引力牵制的天然卫星
all moons are natural satellites
held in place by gravity.
但卫星不只环绕行星转动
But moons do more than
just go around planets,
也发挥稳定作用, 使行星留在轨道
they help stabilise the
planets in their orbits
促使太阳系可以畅顺运作
and keep the machinery of the
solar system running smoothly.
卫星种类繁多
The diversity of moons
一方面建基于可预计的科学定律
is an interesting combination
of predictable laws of science
另方面也是物体相撞后偶然的结果
and then complete randomness
of just things smashing together
完全无法预计
and the chips kind of falling where they
did in a way that you could never predict.
行星和卫星同出一脉
Planets and moons begin the same way.
恒星诞生后, 大批星尘和气体留下
Once a star turns on, there's
a lot of dust and gas left over.
尘埃微粒慢慢集结, 形成岩石
Slowly, the dust particles
clump together, forming rocks.
岩石互撞, 形成巨砾
The rocks smash into each
other and form boulders.
缓慢地, 物体变得越来越大
Slowly, the objects
get bigger and bigger.
这个过程名为「吸积」
The process is called accretion.
就像雪球滚下山坡
One can think of it as forming a
snowball and rolling it down a hill.
滚下山之际
As it, as it rolls down the hill,
积聚的雪越来越多
it collects and gathers up yet more snow
雪球越滚越快, 力度越来越强
which makes it roll faster and harder.
这种不受控的吸积现象
And, and so that process
of runaway accretion
在行星的形成过程中出现
actually happens in the
formation of the planets...
卫星也是如此形成
and in the formation of moons as well.
听起来很简单
It sounds simple enough,
但之前无人肯定
but nobody knew for
sure how it worked...
直至2003年
until 2003.
在国际太空站上
On the International Space Station,
航♥天♥员唐佩蒂特进行零引力实验
astronaut Don Pettit was
experimenting in zero gravity.
他把盐和糖放入塑料袋内
He put grains of salt and
sugar inside a plastic baggie.
它们没有散开, 反而凝集起来
Instead of floating apart,
they began to clump together.
行星和卫星正是如此形成
This is how both planets
and moons build up.
但它们不是围绕恒星
But instead of taking
shape around stars,
大部分卫星是围绕行星而成形
most big moons take
shape around planets.
既然是由同一过程产生
If the same process makes them all,
因何又有不同特性?
what makes all of them so
different from each other?
以木卫四和木卫三为例
Take two of Jipiter's
moons, Callisto and Ganymede.
两颗截然不同的木星卫星
Two very different moons,
都在木星年轻时
each born from the same debris
从同一堆星尘产生
when Jupiter was still young.
木卫三靠近木星, 周围有大量星尘
Ganymede formed close to Jupiter
where there was lots of debris.
因为有这么多材料可用
Because there was so much material,
所以在一万年之间, 迅速成型
it came together quickly
at about 10,000 years.
而且很热
And it was hot.
热力把冰和岩石分开
The heat separated
the ice from the rock.
现在仍可从木卫三独特的地形见到
You can still see it in
Ganymede's distinct landscape.
能量是主宰卫星形状的要素
The primary factor that affects why moons
are the way they are today is energy;
要看吸积过程中, 得到多少能量
how much energy was put into
them as heat during accretion...
之后又失去多少能量
and how much energy has been lost.
这些因素可解构卫星今日的行为
All of those factors go into telling
us why moons behave the way they do
也说明了它们因何有现今的形状
and why the look the way they do today.
木卫四的表面显示另一情况
Callisto's surface
tells a different story.
它在较远处形成, 星尘和热力较少
It formed much farther out where
there was less debris and less heat
形成时间较长, 冷却程度较快
It took longer and cooled faster.
木卫四的表面比木卫三更统一
Unlike Ganymede, Callisto's
surface is uniform:
岩石和冰从来未曾分开过
rock and ice never separated.
成形的位置也主宰卫星的生死
Where a moon forms can also mean the