行星（2019）

静谧的夜空中繁星闪烁
The night sky is ablaze with stars...
单纯我们银河系里的恒星就有数千亿颗
..hundreds of billions in our galaxy alone...
其中有些比太阳更大 更亮 也更辉煌
..many larger, brighter and more majestic than our sun.
从银河系和恒星的角度说 太阳系中的行星
On the scale of galaxies and stars, the planets of our solar system
不过是阳光偶然掠过的
are little more than grains of sand caught momentarily
一颗沙粒
in the light of the sun.
但是40多亿年来 这些微尘之上却写就了
But on those motes of dust, for over four billion years,
许多鲜为人知的壮丽史篇
great stories have played out unseen.
这是关于行星的诞生
Stories of worlds born...
还有消亡的故事
..and worlds lost.
行星在沉寂平静中孕育
Planets forged amongst the calm...
在混沌中成形
..and the chaos.
它们的命运纠缠关联 超乎我们的想象
Their destinies more entwined than we ever imagined.
我们知道这些
We know this...
是因为在过去的数十年间
..because in the last few decades...
我们向太阳系中地球以外的其它7大行星
..we've sent spacecraft to all seven...
都发射过探测器
..of the worlds beyond our own.
我们这里要讲述的就是它们发送回地球的故事
These are the stories that they return to Earth,
也就是行星的故事
the stories of the planets.
行星 第1集
46亿年前
在太阳诞生后的最初数百万年里
For the first few million years after the sun formed,
它的周围还没有行星出现
there were no planets to see it rise...
只有无尽的尘埃和气体
..just clouds of dust and the gas...
这些是太阳诞生时残留的材料
..the leftovers from the birth of the sun.
经过上千万年的时间 这些尘埃开始慢慢结合聚集
Over tens of millions of years, the dust began to stick together...
形成了最早的岩石
..and form the first rocks.
最终这些岩石在引力作用下
Eventually, gravity assembled the rocks
创造出了行星的胚胎
to create planetary embryos...
随后催生出了距离太阳最近的4颗行星
..that in time formed the four closest planets to the sun.
如今水星成为离太阳最近的行星
Today, Mercury is the closest of all,
承受着强烈的太阳光照
enduring the sun's full glare.
从水星继续向外
Further out...
是金星
..lies Venus...
它的表面包裹着浓密的大气层
..chocked by a thick atmosphere.
金星向外的邻居就是我们的地球
Then Venus's neighbour, Earth.
4颗行星中距离太阳最远的是火星
And farthest of all, Mars...
一个寒冷荒凉的世界
..a cold desert world.
它们共同构成了太阳系中仅有的岩石行星
Together, they formed the only rocky so-called terrestrial planets
即“类地行星”
in the solar system.
在这4颗行星中
And of the four...
有一颗显得独一无二
..one is unique.
大家只要放眼四周
Just look at this...
聆听一番
..and listen to it.
一颗行星在经历了
This is what a planet looks and sounds like
40亿年的自然进化后 便有了现在的音容外貌
after four billion years of evolution by natural selection.
太阳系中再也找不到
There is nowhere else in the solar system
与之相似的行星了
that looks and sounds like this,
这一点思索起来很有意思
which is interesting, when you think about it,
因为所有的行星和卫星都是由相同物质构成的
because all the planets and moons and are made out of the same stuff -
包括碳 氮 氧 铁
they're carbon, nitrogen, oxygen, iron.
45亿年前坍缩形成太阳系的尘埃云里
All those atoms were present in the cloud that collapsed
就包含所有这些原子
to form the solar system, four-and-a-half billion years ago.
然而地球却显得格外独特
And yet Earth appears to be exceptional -
它是荒芜太阳系中唯一一颗有生命的行星
a lone living planet in an otherwise desolate solar system.
到底是什么原因让地球显得如此特别呢
So what is it that makes this place so special?
是命中注定 还是巧合
Is it fate? Is it chance?
这些问题非常重要
These are important questions
因为地球是目前我们人类已知的
because Earth is the only place we know of
宇宙中存在的最复杂的现象
where the most complex phenomena in the universe exists,
它赋予了宇宙的意义 那就是生命
the thing that brings meaning to the universe - life.
第一集 沐浴阳光 类地行星
地球是太阳系中一个特别的世界
Earth is a special world in our solar system
甚至在数千光年的范围内也是如此
and perhaps even for thousands of light years beyond.
我们的世界确实有其独特之处
Our world certainly has unique properties.
地球的大小适当 与太阳的距离恰到好处
It's the right size and distance from the sun
这使它在数十亿年里能够保持大气层
to have retained an atmosphere that's protected its oceans
进而保护了地球上赋予生命的海洋
of life-giving water for billions of years.
可当我们离开这颗蓝色星球
But as we've left the blue planet,
去探索其它姊妹行星时
and explored our sister worlds...
我们发现每颗类地行星似乎都有过
..we've discovered that each appears to have had a moment
酷似地球的环境
when it enjoyed almost Earth-like conditions.
每颗类地行星都曾有过生命诞生的机会
Every one of our rocky neighbours has a story of what might have been.
水星 距离太阳5800万公里
水星是一颗备受摧残的小个行星
Mercury is a small, tortured world.
数十亿年的光阴中
More than any other planet,
它始终承受着比其它所有行星更加狂暴的太阳炙烤
it's endured the unflinching glare of the sun for billions of years.
水星是个充满谜团与矛盾的世界
Mercury is a world of mystery and apparent contradictions.
它的运行轨道呈椭圆形
It's in quite an elliptical orbit,
这意味着它在远日点 离太阳是7000万公里
which means it can be as far away from the sun as 70 million km,
近日点却只有4600万公里
but as close as 46 million.
所以正午时
That means that temperatures at midday
水星的地表温度高达430摄氏度
can rise to 430 degrees Celsius on the surface,
到了夜晚因为它很小 本身没有大气层
but, at night, because it's a small planet and it's got no atmosphere,
温度会骤降至零下170摄氏度
temperatures fall to minus 170 degrees.
它也受到了所谓“轨旋共振”的困扰
It's also locked into what's called the spin-orbit resonance,
换句话说 水星每公转两周
which means the planet spins precisely three times on its axis
就可以完成自转三周
for every two orbits
这意味着水星上的一天几乎相当于两个水星年
and that in turn means that its day is twice as long as its year.
也就是说 我以每小时3.2公里的速度
That means that I could walk over the surface like this
在水星表面行走
about 2mph
太阳在空中的位置将始终不变
and keep the sun at the same point in the sky.
我能在水恒的暮色中一直走下去
I could stroll in eternal twilight.
水星是迄今为止人类探索最少的太阳系内层类地行星
Mercury is the least explored of the inner rocky worlds...
因为水星的公转轨道呈奇特的椭圆形
..because getting to a planet in such a strange oval-shaped orbit,
距离太阳太近
so close to the sun...
人类探测水星存在巨大挑战
..is a tremendous challenge.
5 4 3 Five, four, three,
引擎点火 2 1 0
main engine start, two, one and zero.
美国国家航♥空♥航♥天♥局的“信使”号♥探测器升空
And lift off of Messenger on Nasa's mission to Mercury...
“信使”号♥水星探测器 2004年8月
它是太阳系中一颗充满迷雾的行星
..a planetary enigma in our inner solar system.
现在 探测器穿越音障
Now going through the sound barrier.
直接飞向水星明显不切实际
A direct route to Mercury is impractical.
现在要进入最大动压阶段
Now going through the period of maximum dynamic pressure.
探测器抵达目的地时的速度可能太大
A spacecraft would arrive with so much speed
需要大量燃料用于减速
that it would need vast amounts of fuel to slow down
并进入绕水星轨道
and enter orbit around Mercury.
火箭分离成功
We just had spacecraft separation.
“信使”号♥探测器
So Messenger controlled its trajectory
以各行星作为跳板 控制飞行轨道
by stepping from one planet to the next,
同时借助引力降低速度
using gravity to slow itself,
呈螺旋形靠近目标
spiralling inwards towards its target.
一次飞掠地球
两次飞掠金星
即便如此 “信使”号♥接近水星的速度依旧很高
Even so, Messenger approached Mercury at such high speed
不得不三次飞过水星
that it was forced to fly past the planet three times...
通过每次掠过实现减速
..slowing on each pass...
经过将近7年准确无误的飞行后
..until, after almost seven years of flawless navigation,
“信使”号♥终于安全进入绕水星轨道
it arrived safely in orbit.
“信使”号♥探测器的使命是探测水星表面
Messenger set about its mission to map Mercury's surface...
同时它将以前所未有的特写镜头 揭开这颗太阳系中
..and began revealing the secrets of the most cratered planet
陨石坑最密集行星的秘密
in the solar system in exquisite new detail.
柯特兹撞击坑 直径33公里
凝固的岩浆流
卡洛里盆地 最大的撞击坑 1550公里
“信使”号♥探测器能做的
Messenger was able to do much more
不只是拍摄水星表的照片而已
than just take images of Mercury's surface.
通过追踪探测器发射的无线电♥信♥♥号♥♥
By tracking radio signals emitted by the spacecraft,
我们能够从地球上看到绕水星轨道的
we're able to see very slight changes in the orbital path
所有细微变化
around Mercury, as seen from Earth,
由此绘制出水星的引力场
and that allows us to map out Mercury's gravitational field.
探测器上的仪器
There are also instruments that allow us
还能让我们看到水星自转时的
to see how the planet wobbles around
晃动情况
as it spins on its axis.
我们把所有测量数据集中起来