了解宇宙是如何运行的（2010）

How the Universe Works S06E04

Part 4 Dec. 22, 2021, 7:22 p.m.

甲烷会被分解
that the methane breaks up,
甲烷是由碳和氢组成
and methane is made of carbon and hydrogen,
所以如果你把碳压缩到极致
so if you take carbon and you compress it a lot,
你可以得到钻石
you could get diamond formation,
所以完全有可能
and so it is entirely possible
在海王星的液体地幔的海洋里
that literal diamonds are raining down
下着钻石的倾盆大雨
in this ocean of the mantle fluid on Neptune.
从超级风暴到钻石雨
From superstorms to diamond rain,
奇异的海王星，超出了我们的预期
Neptune is strange, dynamic beyond expectation,
但天王星才真正的神秘者
but Uranus is the real mystery,
在于它是太阳系中不同于其他任何事物的
the victim of a cosmic one-two punch with seasons
两轮冲击的受害者
unlike anything else in the solar system.
1986年一月份……
January 1986...
旅行者2号♥ 以每小时超过40000英里的速度接近天王星
Voyager 2 approaches Uranus at over 40,000 miles per hour.
天文学家等待这一刻已经8年了
Astronomers have been waiting for this moment for 8 years,
因为在“旅行者”号♥抵达前
but on voyager's arrival,
我们所知道的只是一个平淡、苍白的蓝色球体
all that's revealed is a bland, pale, blue ball.
作为一个研究地球大气层的
That was a little bit disappointing
科学家
from my perspective
我觉得这有点令人失望
as a scientist studying the atmosphere of the planet.
20年后，一切都变了
20 years later, everything changes.
望远镜显示有巨大的风暴在星球上肆虐
Telescopes reveal huge storms raging across the planet.
为什么会有如此巨大的差异呢？
Why the enormous difference?
答案在于星球极端的轴向倾斜
The answer lies in the planet's extreme axial tilt.
如果海王星和天王星是兄弟姐妹
If Neptune and Uranus are siblings,
天王星绝对是不稳定的兄弟姐妹
Uranus is definitely the wonky sibling.
所有的行星♥相♥对于太阳系都是倾斜的
All the planets are tilted with respect to the solar system.
地球是23度
The Earth is 23 degrees.
木星只有几度
Jupiter is just a handful of degrees,
但天王星实际上是侧躺着
but Uranus is actually on its side.
它倾斜了98度
It's tipped 98 degrees.
天王星的倾斜度几乎是
Uranus' tilt is almost four times more extreme
太阳系中其他行星的四倍
than any other planet in the system.
它平躺着，所以它的两极是水平的
It's lying so its poles are horizontal,
它的环和卫星♥相♥对于
and its rings and moons are vertical relative
太阳系的平面是垂直的
to the plane of the solar system.
地球的倾斜使得四季分明
Earth's tilt gives it seasons.
天王星的极端倾斜给了它极端的季节
Uranus' extreme tilt gives it extreme seasons.
它的两极每年有两次直接指向
Twice a year, its poles are pointed directly towards
或远离太阳
or away from the Sun,
所以每个极地都有一个非常强烈的午夜太阳
so each pole has a very intense period of midnight sun
和一个黑暗寒冷的极地之夜
and a dark, cold polar night.
天王星绕太阳公转需要84年
It takes Uranus 84 years to orbit the Sun,
所以这些季节会持续很长时间
so those seasons last for a very long time.
比如，在绕太阳公转的过程中
You get, like, 20 years of sunlight
当北半球有20年的日照时
in the northern hemisphere as its going around the Sun
而南半球则有20年的黑暗
and 20 years of darkness in the Southern hemisphere.
天王星有点像“权力的游戏”
Uranus is kind of like "game of thrones."
你等了很久的冬天的到来了
You're waiting ages for winter to come,
然后冬天却持续了20年
and then winter lasts 20 years.
一个持续了几十年的
A winter's night or a summer's day
冬夜或夏日
that lasts for decades.
这就意味着，在公转期间，如果太阳光照射到它旋转的赤道
But what happens in the interim when the orbit of the planet
而不是它的一个极点时
means the Sunlight hits its spinning equator
会发生什么呢？
rather than one of its poles?
当它移到另一边时，整个星球都被照亮了
When it's off to the side, the whole planet's lit up.
在它旋转的过程中，星球的每一块都暴露在阳光下
As it spins, every piece of the planet is exposed to sunlight.
阳光照射到旋转行星的赤道
Sunlight hits the equator of the spinning planet,
将能量泵入表面，使大气变暖
pumping energy into the surface, warming the atmosphere
并驱动星球周围的气流
and driving air currents around the planet.
其结果……就是春天和秋天的暴风雨
The result... Spring and Autumn storms.
天王星大气层中阳光分布的
That extreme change in how much sunlight is distributed
极端变化可能对
across that planet's atmosphere
我们在天王星大气层中看到的
probably has an important role
这种显著的季节变化
in driving this remarkable seasonal change
起着重要作用
we see in Uranus' atmosphere.
与它的冰巨人兄弟海王星不同
Unlike its ice giant sibling, Neptune,
天王星的风暴是有季节性的而不是恒定的风暴
Uranus has seasonal storms rather than constant ones,
那么为什么天王星是这样绕着太阳转
so why does Uranus roll around the Sun
而其他行星却像陀螺一样旋转呢？
while other planets spin like tops?
这与我们所知的行星形成过程背道而驰
It goes against everything we know about planetary formation.
从某些方面来说，在太阳系中形成新行星
In some ways, forming new planets in the solar system
很像制♥作♥棉花糖
was a lot like making cotton candy.
有一个方向，所有的东西都在一起
There was a direction that everything was coming together.
如果你把一根棍子放进去
If you put a stick down in it,
物质会以一定的方向聚集在它周围
the material would accumulate around it
这就是为什么所有行星都有
in a certain direction, so that's why all the planets
大致相同的轨道轴的原因
have roughly the same orbital axes.
如果天王星一开始有一个垂直的轨道轴
If Uranus started out with a vertical orbital axis,
那它是如何翻转过来的呢？
how did it end up flipped on its side?
我们知道在早期的太阳系中
We know there were a lot of collisions between planets
有很多行星或行星大小的物体之间会相互碰撞
or planet-sized objects in the early solar system.
人们很自然地认为天王星可能是
It's natural to assume that Uranus probably got hit
受到了另一个巨大物体的轻微撞击
as a grazing impact from another giant object,
导致它向一侧倾斜
which tipped it over on its side.
但是这个假设有一个问题
But there's a problem with this assumption.
如果你对天王星进行一次简单的撞击
If you hit Uranus with a single impact to knock it over
把它撞翻到98度
to 98 degrees,
那么实际上你所期望的是，剩下的光环
then actually what you expect is that the rings left over
相对于行星的自转方向
would be orbiting in the wrong direction
将是错误的
relative to the spin of the planet.
什么样的事件可以强大到
What event could be powerful enough
足以翻转一颗行星
to flip a planet,
但又温和到可以把所有围绕它的东西
but gentle enough to bring everything in orbit around it
都带到轨道上？
along for the ride?
一次单独的大碰撞
A single big collision
不可能会发生在天王星上
is probably not what happened to Uranus
因为那会造成太大的破坏
because that would've been too disruptive.
有点像拳击
It's kind of like boxing.
不是一次致命一击，而是弱的一拳二拳
Instead of one big knockout blow, it was the old one-two.
一种理论认为
One theory suggests that
新形成的天王星被一颗地球大小的
the newly formed Uranus is hit by a protoplanet
原行星撞击
the size of Earth.
这一击只是掠过
The blow is only glancing.
天王星被撞向它目前的倾斜方向
Uranus is knocked partway towards its current tilt.
它的环系统经受住了撞击
Its ring system survives the impact
停留在赤道附近的轨道上
and stays in orbit around the equator.
当第二个天体撞击天王星时，天王星一路倾斜
As the second object hits, Uranus is tipped all the way,
光环随之变化
and the rings follow.
天王星被戳了一下，然后撞到了一边
Uranus got jabbed and then knocked on its side.
虽然天王星侧躺着绕太阳运行
Uranus may orbit the Sun sideways,
但是海王星的卫星，海卫一，有一个更奇怪的轨道
它反向绕海王星运行，但更奇怪的是，它似乎正在喷发
甚至可能孕育生命
but Neptune's moon, Triton, has an even stranger trajectory.
It travels around Neptune in reverse.
But weirder than that, it seems to be erupting,
and it could even harbor life.
无论我们在哪里看到行星，我们都希望看到卫星
Wherever we see planets, we expect to see moons.
似乎行星越大，围绕它运行的卫星就越多
It seems the larger the planet, the more moons orbit around it.
木星有69个土星61个
Jupiter has 69. Saturn, 61.
接下来是冰巨人
Next come the ice giants.
到目前为止，天文学家已经在天王星周围发现了27颗卫星
Astronomers have so far detected 27 moons around Uranus
在海王星周围发现了13颗
and 13 around Neptune.
但有一个完全脱颖而出……
But one stands out completely...
海王星的卫星，海卫一特里同
Neptune's moon, Triton.
海卫一有点奇怪
Triton is a bit of an oddball
因为它不是沿海王星自旋的
because instead of orbiting Neptune in the same direction
同一方向运行
that Neptune spins,
而是沿相反的方向运行
it orbits in the opposite direction,
我们称之为逆行轨道
what we call a retrograde orbit.
一个巨大的行星和它的卫星
A giant planet and its moons
是由相同的气体、尘埃和岩石物质
form out of the same swirling disk of gas,
组成的漩涡盘形成的