行星（2019）

we've uncovered a graveyard of failed worlds...
它们在形成时遭到了神秘的打断
..their growth mysteriously cut short.
据说所有这些异常现象
To cause all these anomalies,
很可能是太阳系诞生初期发生的
it's thought that something catastrophic must have happened
某个灾难性事件造成的
very early in the solar system's history.
所有证据表明大约45亿年前
All the evidence suggests that around 4.5 billion years ago,
木星轨道开始发生移♥动♥
Jupiter's orbit began to change,
由此引发了一段前所未见的狂暴时期
triggering a period of unprecedented violence
彻底改变了年轻太阳系的面貌
which completely transformed the face of the young solar system.
我们知道这点 是因为这颗四处掠夺的行星
And we know this because the marauding planet
留下了一连串的毁灭痕迹
left a trail of destruction in its wake.
木星在其生命早期 开始向内太阳系移♥动♥
Early in its life, Jupiter began to move inwards towards the sun...
这种内向迁移的影响至今仍清晰可见
..and the effects of that journey can be seen to this day.
小行星带 现在
小行星带位于火星和木星的
In between the orbits of Mars and Jupiter...
轨道之间
..lies the asteroid belt...
它是一片充斥着
..a desolate wasteland of debris
太阳系形成初期残留碎片的荒芜之地
left over from the beginning of the solar system.
这些岩石星体个头太小 本身无法成为行星
Rocky bodies too small to be planets in their own right.
科幻电影中经常把小行星带描绘成
In science fiction films, the asteroid belt is often depicted
一堆无法通航的翻滚碎石
as an un-navigable mass of tumbling rubble.
但事实并非如此
But it's not like that at all.
事实上 现代探测器能够
So much so, in fact, that modern spacecraft engineers
在无需修正航线的情况下 顺利穿过小行星带
can fly a spacecraft through without making any course corrections.
原因就在于小行星带的物质非常稀薄
The reason for that is there's not much mass in the asteroid belt.
所有这些小行星的质量总和只有月球质量的4%左右
A sum total of all of them is only about 4% the mass of the moon
而且它们广泛分布在
and they're spread out in a huge sort of ring,
火星轨道外的巨大圆环内 所占的空间十分广阔
out beyond the orbit of Mars. So, it's a vast amount of space.
这意味着任何两颗大型小行星间的平均距离
That means that the average distance between any two large asteroids
大约是地球和月球之间距离的8倍
is about eight times the distance between the Earth and the moon.
所以我可以站在一颗巨型小行星上
So, I could stand on one of those large asteroids
远眺太空
and look out into space
我最近的邻居可能只是黑暗中一颗暗淡的星星
and my nearest neighbour would just be a dim star in the dark.
但是散落在小行星带的
But scattered amongst the rubble are objects
不只是岩石
that are far more than mere rocks.
5 4 3 Five, four, three,
2 主发动机启动 1 0
two, main engine start, one, zero and lift off
美国国家航♥空♥航♥天♥局 “黎明”号♥探测器
德尔塔二号♥火箭升空
of the Delta II Rocket.
2007年 美国国家航♥空♥航♥天♥局的“黎明”号♥探测器
In 2007, Nasa's Dawn mission
前往小行星带探索最大的两颗小行星
was sent to explore the two largest objects in the asteroid belt.
在环绕巨型小行星灶神星运行一年后
After a year in orbit around the giant asteroid Vesta...
2015年3月
..in March 2015...
“黎明”号♥探测器最终靠近这颗质量
..Dawn made its final approach on a body so large
超过整个小行星带三分之一的巨大天体
it makes up almost a third of the mass of the entire asteroid belt...
谷神星
..Ceres.
“黎明”号♥传回地球的第一批照片
On arrival, the first images Dawn sent back to Earth
包含一个完全出人意料的发现
contained something entirely unexpected...
美国国家航♥空♥航♥天♥局 “黎明”号♥拍摄图像
谷神星最大的一个陨石坑中存在神秘的亮斑
..mysterious bright patches in one of Ceres' largest craters.
这些照片的光谱分♥析♥结果显示
Spectral analysis of the images
这些亮斑其实是
showed that the patches were, in fact,
液态水留下的盐渍
the salty residue left behind by liquid water...
这说明它的地壳深处可能隐藏着
..suggesting there must be large amounts of ice
大量的水冰
just beneath the crust.
“黎明”号♥探测器随后发现谷神星地表存在300多个亮点
Dawn went on to discover over 300 bright spots all over the surface.
这说明在薄薄的地壳下
And this means that beneath this thin crust,
谷神星的岩石内核周围是厚厚的 富含水冰的地幔层
Ceres has a thick ice rich mantle surrounding its rocky core...
换句话说 这颗矮行星存在分层结构
..evidence that the dwarf planet is made up of multiple layers.
谷神星的内部与小行星带的其它任何天体都不同
The interior of Ceres is like nothing else in the asteroid belt.
“黎明”号♥所发现的这种分层结构
The differentiation, that separation into layers, observed by Dawn
更像是行星 而不是小行星的特征
is more characteristic of a planet than an asteroid.
所以45亿年前 谷神星正处于
So, 4.5 billion years ago, Ceres was well on its way
成熟酝酿阶段
to becoming a fully-fledged world.
谷神星 45亿年前
据说谷神星在婴儿时期就表现得与众不同
It's thought that's in its infancy Ceres was very different.
如今冻结在其内部的水冰曾经是大量的液态水
The water that now lies frozen within its interior was once liquid.
表面仅有一层薄冰覆盖
Protected beneath a thin layer of ice...
谷神星可能曾拥有遍布全球的咸水海洋
..Ceres was once covered by a deep saltwater ocean.
谷神星还没来得及释放潜能
Before Ceres had reached its full potential,
一场巨型骚动引发的冲击波
a great disturbance sent shock waves through
穿过后来的小行星带袭来
what would one day become the asteroid belt
使它的成长戛然而止
and cut its development short.
小行星带 45亿年前
木星在围绕年轻的太阳公转时
As Jupiter circled the young sun,
一路披荆斩棘 在覆盖早期太阳系的气体和尘埃中
it started to clear a path through the gas and dust
清理出了一条通道
that shrouded the early solar system...
这个过程中它的表现令人担忧
..but that process caused it to do something alarming.
它与这些气体的相互引力作用 使这颗气态巨行星
Gravitational interactions with the gas made the giant planets
向着太阳内侧呈螺旋运动
spiral inwards towards the sun...
它直接穿过后来成为
..ploughing straight through the region of space
小行星带的空间区域
that would become the asteroid belt...
将谷神星原本积蓄的形成物质
..scattering the material from which Ceres
彻底击散
would otherwise have grown.
早期太阳系的计算机模拟结果显示
Computer simulations of the early solar system
小行星带曾经获得了足够物质
suggest that the asteroid belt once contained enough material
来形成一个地球大小的行星
to build a planet the size of the Earth.
那也许曾经是谷神星的命运
And perhaps that was Ceres's destiny.
可是当木星经过时
But when Jupiter passed through,
它99.9%的形成物质都散失到了太空中
it scattered 99.9% of the material away,
谷神星的命运已然注定
and Ceres's fate was sealed.
在之后的一亿年里 谷神星的海洋完全冻结
Within 100 million years, Ceres's ocean froze
并深埋于地壳之下
and was buried beneath its crust.
这颗年轻的行星还没等践行诺言
The young planet's development cut short
生命的脚步就夏然而止
before it could fulfil its promise.
但是木星的恐怖统治还远远没有结束
But Jupiter's reign of terror was far from over.
它继续向着太阳内侧
It would continue its journey inwards
朝我们地球即将形成的地方前进
towards the place our planet was beginning to form...
严重威胁地球的存在
..threatening the very existence of Earth.
木星凭借其强大的引力场对年轻的太阳系
Jupiter had such an overwhelming effect on the young solar system
产生了震憾性的影响
because of its powerful gravitational field...
这些影响至今仍旧清晰可见
..the effects of which we can still witness today.
木星通过它的引力场对整个太阳系
Jupiter exerts its influence across the solar system
施加了影响
through its gravitational field...
它是迄今为止所有行星中最强大的一颗
..which is by far the most powerful of all the planets,
因为木星在所有行星中质量最大
because Jupiter is the most massive of all the planets.
大约是地球质量的320倍
It's about 320 times the mass of the Earth.
这就是它产生惊人破坏力的原因所在
That's why it was so destructive in the past.
如今 我们可以看到它的引力场
And we see the power of that gravitational field today
对木星最近的卫星木卫一的影响
in its influence on the closest of Jupiter's largest moons, Io.
木卫一 现在
木卫一是太阳系中火山活动最活跃的星球
Io is the most volcanic world in the solar system.
它的表面覆盖着成百上千座活火山
Its surface covered with hundreds of active volcanoes...
还有众多的熔岩湖
..and lakes of molten lava.
其中最大的熔岩湖名为洛基火山口
The largest, known as Loki Patera,
直径超过了200公里
is more than 200km in diameter.
是地球上任何熔岩湖面♥积♥的100万倍
A million times the area of any lava lake on Earth.
四处流窜的熔岩流不断侵袭着木卫一的表面
Its surface tormented by waves of molten rock.
这里俨然就是人间地狱
Io is a vision of hell...
而始作俑者就是强大的木星引力
..created by the moon's proximity to Jupiter.
地球上所有火山活动的能量都来自地下深处的
Volcanism here on Earth is powered by the internal heat
内部热量
down below the surface.
现在这些地热
Now, much of that is residual heat
大约有一半来自
left over from the Earth's formation
45亿年前地球形成时产生的余热 另一半则来自
four-and-a-half billion years ago, about half of it, and the other half
地核周围各种化学元素的放射性衰变
is down to radioactive decay of elements around the Earth's core.
然而 木卫一的情况却截然不同
Now, on Io it's different.
它是一颗较小的卫星
Io's a much smaller world
肯定不会保留太多余热
and so it didn't retain much residual heat.
所以木卫一的火山能量来自不同的过程
So, there, the volcanoes are powered by a different process.
就是所谓的“潮汐加热”
It's known as tidal heating.
在木卫一上驱动火山活动的
The energy that drives Io's volcanism
并非卫星内部的热能
doesn't come from heat stored within the moon.
而是引力作用
It's generated by gravity...