了解宇宙是如何运行的（2010）

How the Universe Works S08E09

Part 4 Jan. 30, 2022, 2:59 p.m.

are hiding in our own backyard.
♪
[汽车喇叭声]
[ car horns honking ]
♪
在纽约市，在建筑物和交通中
in new york city, amongst the
buildings and traffic,
我们发现了冰碛石
we find moraines,
即冰川消退后留下的岩石
rocks left behind
by retreating glaciers.
♪
一万八千年前
18,000 years ago,
一片比任何摩天大楼都高的冰层覆盖着曼哈顿
a sheet of ice taller than any
skyscraper covered manhattan.
在整个地球历史上，冰川期都有规律地发生
Ice ages have struck regularly
throughout earth's history,
使我们的星球陷入深度冻结
putting our planet
in a deep freeze.
[冰裂]
[ ice cracking ]
杜尔达:数亿年前，地球历史上
durda: There was a period
in earth's history
有一个时期
several hundred
million years ago,
雪球地球时期
the snowball earth period,
当我们经历了一个非常极端的冰河期
when we went through
a very extreme glaciation,
的确是一个非常极端的冰河期
if you will,
a very extreme ice age
我们认为也许整个地球
where we think perhaps
the entire earth
都被冰盖覆盖了
was covered in an ice sheet.
是什么触发的？
Narrator: The trigger?
地球绕太阳公转
Earth's orbital dance
around the sun.
♪
我们倾向于认为自己坐在地球上
we tend to think of ourselves
是相对静止不动的
sitting relatively stationary
on the earth.
其实这很令人欣慰
It's pretty comforting,
actually,
但我们绕太阳运行的速度大约是每小时66000英里
but we're orbiting the sun
at about 66,000 miles per hour.
地球每天围绕太阳运行
Narrator: Every day, earth
travels over 1.6 million miles
160万英里
on its journey
around the sun.
这个轨道并不总是完全圆的
This orbit isn't always
completely round.
♪
地球围绕太阳公转的轨道
earth is generally going
around the sun
大致是圆形的
in more or less
a circular orbit,
但随着时间的推移，太阳和月球
but over time, the massaging
of this orbit from the sun,
对地球轨道的影响
from the moon
on the earth's orbit
使地球的轨道发生了变化
causes the orbit of the earth
to change
所以有时它是椭圆形的
so that sometimes
it's an ellipse.
有时它更像是一个圆
Sometimes
it's more of a circle.
♪
现在在地球上
right now on the earth,
我们处于轨道上最圆的时间
we're in kind of the most
circular time in the orbit,
这意味着夏天相对温和
so that means the summers
are relatively mild,
冬天也相对温和
and the winters
are relatively mild,
但想象一下，在不久以前
but imagine not that long ago
in the past,
情况可能会截然不同
it could have been really
dramatically different.
当地球离太阳更近的时候
When the earth is a little bit
closer to the sun,
可能会有一个非常严酷的夏天
maybe you have
a really severe summer,
而在轨道的另一边
and then on the other side
of the orbit,
你离太阳的距离比平常要远一些
you're a little farther away
from the sun than normal,
所以你会有一个非常严酷的冬天
so you have
a really severe winter.
♪
我们的环境对这些东西非常非常敏感
our environment is very,
very sensitive to these things,
当地球轨道被拉长时
and when the earth's orbit
is stretched out,
就会引发冰河时代
that can actually
trigger an ice age.
♪
地球10万年的轨道周期
narrator: Our planet's
100,000-year orbital cycle
导致了冰河时代，纽约被掩埋
caused the ice age
that buried new york.
冰河时期对人类历史产生了巨大的影响
And ice ages have had a big
effect on human history.
一万五千年以前
15,000 years ago,
急剧下降的气温将水
plunging temperatures
locked water away
锁在冰川和冰帽中
in glaciers and ice caps.
海平面下降，形成了大♥陆♥之间的陆桥
Sea levels dropped, creating
land bridges between continents.
人类从亚洲徒步迁移到美洲
Humans migrated from asia
to america by foot,
于是美洲第一次有人类居住了
and for the first time,
america was inhabited.
♪
2018年5月——科学家揭示了地球之旅的
may 2018 -- scientists revealed
a whole new dynamic
全新动态
to earth's journey.
♪
每40.5万年
every 405,000 years,
我们星球的轨道旅行就会延伸到极限
our planet's orbital voyage
stretches to the extreme,
而这都是地球的邻居们造成的
and earth's planetary neighbors
are to blame.
因为木星是太阳系中
Because jupiter is the most
massive planet
最大的行星
in our solar system,
它在很多方面都是操场上的恶霸，对吧？
it is in many ways the bully
on the playground, right?
它的动力学，它的引力塑造了很多
Its dynamics, its gravity
sculpts a lot of the dynamics
太阳系的动力学
of the solar system.
♪
杜尔达:它实际上是在拉扯
durda: It actually tugs
and pulls on the orbit
地球的轨道
of the earth itself.
它导致了一些变化
It's responsible for some of
the very changes
驱动着地球上的气候循环
that drive our climatic cycle
here on our planet.
♪
木星并不是游乐场里唯一的恶霸
narrator: Jupiter isn't the only
bully in the playground.
♪
泰勒:金星是一个与地球
thaller: Venus is
a fairly big planet
大小相当的星球
about the size of the earth
在其轨道上离我们最近
and also comes closest
to us in its orbit,
所以这两颗行星的相互作用使地球的轨道
so these two planets put just
a little tiny elongation
只稍微延长了一点
onto our earth's orbit,
但随着周期的继续，它变得越极端
and as the cycle continues,
the more extreme it gets,
我们实际上可以注意到
we can actually notice
a temperature difference
大约每405000年发生一次的温差
that happens about once
every 405,000 years.
♪
木星和金星在地球的引力作用下联合起来
narrator: Jupiter and venus gang
up on earth gravitationally,
把地球的轨道拉进一个更大的椭圆
pulling earth's orbit
into an even greater ellipse.
我们星球上炎热的天气变得更热
Our planet's hot weather
becomes hotter,
寒冷的天气变得更冷
and its cold weather
gets much colder.
♪
今天，我们正处于周期的中等阶段
today, we're in a moderate
part of the cycle,
但在短短6万年的时间里
but in just
60,000 years time,
我们可能会陷入另一个深度冻结
we could plunge
into another deep freeze.
这有点像宇宙蝴蝶效应
It's a little bit like
a cosmic butterfly effect.
我的意思是，即使是最小的影响
I mean, even
the smallest effects
随着时间的推移也会产生很大的影响