宇宙（2007）

The Universe S01E11

Part 4 April 22, 2021, 8:13 p.m.

The time for Uranus To orbit the Sun Is about 84 years,
绕太阳一周需要84年
Which means that For half of that time Of 40 years,
这意味着
One hemisphere is in sunlight,
一边大气是阳光照射一边是一遍黑暗
And the other hemisphere Is in dark.
It's like the arctic circle On Earth, except for It's the whole planet.
就像地球上的两极地区一样
有时我们的星球
That tilt is so extreme that, In a sense,
南极是白天
The whole northern hemisphere Is the arctic
北极是黑夜
And the whole Southern hemisphere Is the antarctic.
大气是不时变化的
天王星吸收太阳光
Uranus owes its cool Bluish-green color to methane.
表面只吸收红色光
The methane absorbs Red and orange wavelengths From sunlight
但反射了蓝色光、绿色光
But reflects blue and green.
And its soft appearance Is due to something
这种做法就相似于
That's familiar to anyone Who lives in a big city--smog.
住在大城市里面的人一样
所以加利福尼亚曾经很小
In southern California, We're used to smog,
Which is Photochemically produced Haze material
要生产更多的东西艾德?斯通加州理工大学／喷气推进实验室
Which gives a hazy appearance In the atmosphere.
以求更快的发展
This is similar To the atmospheres Of the four gas giants.
这就是相似于天王星上面的大气
其他的行星没有这种大气
In the outer planets,
There's methane, Which is natural gas.
Sunlight converts it To complex particles as well,
太阳光直射过来很猛烈
Which forms a haze,
Which is the reason That planets don't have A very sharp
所以就没有看起来这么舒服了
But have a fuzzy look to them.
Scientists speculate That Uranus And its celestial neighbor,
科学家推测天王星
和它的太阳系邻居一海王星
Neptune, formed the same way.
性质是一样的
As the early Proto-planetary disc of gas
在早期太阳系刚形成的时候
And dust In our solar system settled,
木星汇集了大量的物质
Jupiter and Saturn gathered up The most material
And became the largest Of the gas giants.
变成了最大的行星
As Jupiter And Saturn's orbits grew,
在木星变大的时候
They destabilized The planetary system as a whole.
太阳系不断发生变化
Dynamic interactions Pushed Uranus and Neptune
占了太阳系的主导力量
把许多物质吸引到太阳系中来
Outward to the edge Of the solar system At an accelerated rate
形成了许多风暴
Where they feasted On icy objects.
还有许多冰冷的天体
They have a lot Of that initial gas,
它吸引了许多气体
But they also gathered A lot of icy material
气体又变成冰物质
And some rocky material In their formation.
许多冰物质构成了许多天体
So consequently,
所以结果就是
Although they have this Surrounding envelope of hydrogen
形成了一些气态行星
And helium gas and some methane, Some nitrogen, some other stuff,
就像天王星一样
They also have A lot of icy material In the inside.
它同样在里面聚集了许多的冰物质
这些冰物质让天王星和海王星成为了气态行星
These icy interiors Have led some
To call Uranus and Neptune The ice giants.
但它们的相互碰撞中
But it's incorrect To imagine them As balls of solid ice
有产生了一些特别的行星
That an astronaut Could walk across.
我都不敢想象
Well, if we dropped An astronaut or a probe
Towards the center of Uranus Or Neptune,
上亿年前事情
Well, first of all,
搞明白是很困难的
They'd be in a lot of trouble.
There's really no solid surface That they could stand on.
我们只知道一些表面的东西
There may be a small rocky core At the center of these planets,
也许是其他的一些东西形成这行星的
But the pressure That they would be experiencing
但压力是很重要的因素
From the atmosphere overhead
And this liquidy icy region Would crush them,
这些冰物质受到压力
Would be millions of times The pressure that we have
上百万吨♥的冰物质在这压力之下
From our own atmosphere For example.
So they would be flattened
所以我们看到它们的表面这个样子
Well before they ever reached The solid surface.
While the other gas giants Have wild weather patterns,
其他的气态行星又是另一番模式
天王星是很典型的
Uranus seems to be Relatively calm,
and scientists Think they know why.
科学家现在还想着这是为什么啊
天王星是个气态行星
Uranus is unique Among the gas giant planets
In that it is the only one That doesn't have
它是唯一可以吸引热量的
An internal heating source.
Jupiter, Saturn, and Neptune All have heat coming
还可以吸引其他行星的热量
From deep within the planet,
And that helps Drive the circulation
它们之间热量互相交换
And explains why we see A lot of the banded structure
这就解释了为什么天王星上面有光环了
That we do On those other three planets.
天王星没有其他的热源
Uranus doesn't have This internal heating source.
天王星的发现也是很特别的
Uranus has another claim To fame, The way in which
是由威廉?赫歇耳在1781年发现的
It was discovered By astronomer William Herschel In 1781.
当时，被人所知的行星就是
At the time,
The only known planets
Were the six visible To the naked eye from Earth,
距离地球都不太远
But Herschel first laid eyes On Uranus through a telescope.
但赫歇耳首先用望远镜发现了这个行星
Herschel Was an amateur astronomer,
赫歇耳是多才多艺的
Professional musician And an optician,
So he had the knowledge And ability to generate
他在那时有能力制♥造♥先进的望远镜赫歇耳望远镜
The best telescopes in the world At that time.
The discovery of Uranus Was incredibly significant
天王星的发现意义是重大的
In the history of humanity
Because it was the first planet Discovered by telescope,
是第一个是由望远镜发现的行星
The first planet That the ancients Didn't know about.
是第一个人们那时对它一无所知的行星
在1977年
In 1977, Nasa's Kuiper Airborne observatory
美国宇航局的科学家又有令人兴奋的发现
Made another exciting discovery
When astronomers Aimed their telescope at Uranus.
他们把天文望远镜对准了天王星
They were planning to watch A fairly common Astronomical event,
他们就要观看天王星的经过一颗星星
The passage of the planet In front of a star.
天王星就要挡住那颗星星
But as Uranus closed in, The star suddenly winked.
但当天王星靠近时
这行星突然出现了光环
实际上，掩星前出现5次
In fact, it seem to flicker On and off five times As it neared the planet
以及掩星后出现5次忽暗忽亮现象
And then several more times As it emerged on the other side.
出现了几次之后就走到一边去了
What was the cause Of this strange phenomenon?
天王星的光环是怎么形成的呢
经过天文学家们的分♥析♥确认天王星也有光环
The flickering star Was actually passing Behind five planetary rings
是9条细环宽度约10万千米
Features that had Only previously been seen On Saturn.
Subsequent observations From the ground
还有进一步的研究
还有利用到了航♥天♥器
And then the Voyager spacecraft,
Confirmed the rings' existence.
证实了天王星光环的存在
And observations made in 2005 From the Hubble Space Telescope
再进一步用哈勃望远镜观察
观察到在天王星的外面
Found a second set of rings Orbiting almost twice
As far away from the planet As the previously known rings.
同时存在着多条光环
Unlike Saturn's Thick, icy rings,
不像其他的冰光环
天王星的光环是厚，粗
Uranus' are dim and thin,
暗色的光环
Comprised of dark rocky dust.
Some of uranus' dusty rings Were likely formed by the impact
有些暗色光环
也许就是由一些陨石
Of a meteor or a comet With one of the planet's 27 moons.
或者彗星组成的
The inner rings Could be the result
在里面的光环
Of collisions Between the moons themselves,
间隔着行星本身和它的卫星
Especially the 13 that orbit In the planet's Kinetic inner swarm.
可能是卫星旋转的轨道
There are a lot Of inner moons around Uranus,
许多内卫星都会产生光环的
Moons that are very small And close to the planet.
许多这种卫星都是小的和行星很近
They tend to have Very fast orbits On the order of maybe a day.
它们转得非常快有的也许一天就可以绕行星一周
其他的卫星旋转天王星一周
Other moons zip around uranus In just 12 hours.
只要12小时
By comparison,
和我们的月球比较
Our moon circles a planet Four times as small,
And takes 28 days to do it.
月球要花至少28天才能绕地球一周
With Uranus' moons Speeding around the planet Like race cars,
天王星的卫星绕着天王星转就像赛车了
It's only a matter of time Before two of them end up
这样的话，两个卫星之间
In another cosmic collision.
迟早会发生碰撞的
Circling the planet Uranus Is a swirling system of moons.
研究行星体系
要涉及到卫星的体系
Even within the last decade,
即使过去十年之内
Substantial changes Have been detected In their unruly orbits.
因为轨道交叉发生碰撞现象
时有被观察到
Scientists believe
科学家认为
It's only a matter of time Before two of them cross paths.
其中两个迟早会发生碰撞的
You can be very certain
你能和上百万年比较艾德?斯通加州理工大学／喷气推进实验室
That in the period of a million Or a few million years
That some of them Will collide with each other.
宇宙中发生过多少碰撞事情啊
I'm thinking particularly Of Cupid and Belinda,
我想着特别是那两个小卫星迈克尔?密斯察纳喷气推进实验室
Which are two small moons
That happen to be orbiting Very close to each other.
碰巧互相靠的很近
Travelling at just A few hundred miles apart,
一极高的速度前进
科学家预料到
Scientists expect That at some point, these moons,
在某一地方，只是时间问题这些卫星会与越来越近
Due to gravitational forces That they impart Upon each other,
Will eventually collide And rip each other apart.
最后发生碰撞
把一个卫星撞去一大块
It will be a bad day For the moons,
这就是卫星的死亡之日