美国国家航空航天局“信使”号水星探测器发射升空 Lift off of Messenger on Nasa's mission to Mercury.
水 星
金 星
火 星
木 星
土 星
天 王 星
海 王 星
行星 第3集
沿着内太阳系向外 Beyond the inner solar system...
穿过小行星带 ..past the asteroid belt...
木星便映入眼帘 ..lies Jupiter.
木星 距离太阳7.8亿公里
它是太阳系中体积最大的行星 一颗气态巨行星 The largest of the planets is a giant swirling ball of gas...
它表面斑驳的花纹是肆虐的风暴 ..its marbled appearance generated by violent winds
经过木星云层时形成的 that rage through its clouds.
木星是一个既陌生又遥远的世界 Jupiter is a world as strange as it is remote.
如果你向上空飞行大约100千米左右 If you fly upwards, only about 100km or so,
你就能到达大气层边缘和漆黑的太空 you reach the edge of our atmosphere and the blackness of space.
距离并不遥远 It's really not that far.
可一旦置身太空 But once you're in space,
衡量距离的尺度就变得超乎想象 the distance scales are sort of incomprehensible.
金星是距离地球最近的行星 大约为4000万公里 I mean, Venus, the closest planet, is over 40 million kilometres away.
木星离地球大约为6.5亿公里 Jupiter around 650 million kilometres.
飞行最快的探测器也要数年才能到达 It takes our fastest spacecraft years to get there.
所以其它行星可能会影响地球 So, the idea that those planets could have any influence on us
人类的想法似乎有些异想天开 here on Earth seems fanciful.
事实上 如果你说的是 And, indeed, if you're talking about
遇到陌生帅哥的几率 your chances of meeting a handsome stranger
或者需要在周三时调整未来一周的生活安排 or your life plans requiring a moderate reconfiguration
那确实不会有影响 about a week on Wednesday, then you would be right.
但是如果要涉及到更深刻 更深层次的问题 However, if you ask more profound questions, deeper questions like,
比如地球为什么是这样 "Why is the Earth the way that it is?
地球上为何存在生命 "Why is there life on Earth?
人类为何存在 "Why do we exist at all?"
那么事实证明这些行星 特别是木星 then it turns out that the planets, and Jupiter in particular,
对地球具有深远影响 have had a profound effect.
在生命初期 年轻的木星就开始横冲直撞 Early in its life, the young Jupiter went on the rampage.
这颗气态巨行星开始了穿越太阳系的 The giant planet embarked on a voyage of destruction
毁灭之旅 across the solar system...
它改写了太阳系各大行星的命运 ..that transformed the destiny of the planets,
改变了地球上的生命历程 and the course of life on Earth.
木星是太阳系的守护者 Jupiter is the godfather of the planets.
对木星的探测研究有助于我们了解整个太阳系的形成 Understand it and you understand how the solar system came to be.
教父 木星
在地球上 我们能够一瞥木星的巨大威力 On Earth, we can see glimpses of Jupiter's power...
这些就是它在地球表面 ..in the scars it's left...
留下的伤疤 ..on the face of the planet.
这是美国亚利桑那州的巴林杰陨石坑 This is the famous Barringer Meteor Crater in Arizona.
它的直径大约是1000米 It is about a kilometre across,
从火山口边缘到底部深170米 170 metres from the rim to the crater floor
大约5万年前 and it was created about 50,000 years ago
一颗直径50米的陨石以每秒13公里的速度 when a meteorite, 50 metres across, entered the Earth's atmosphere
撞入地球大气层 travelling at about 13km per second.
这就意味着它从进入地球大气层 That means it would have taken around, what, seven seconds
到落地的时间大约需要7秒钟 to go from the top of the atmosphere to the ground
它撞击地球的力度很大 释放出的能量相当于 and it hit with such force that the energy released
1000万吨炸药爆炸的当量 was equivalent to ten megatons of TNT.
它就像一枚巨大的核弹 And that is a very large nuclear bomb.
科学界认为 The meteorite that hit the Earth here
这颗撞击地球的陨石来自小行星带 is thought to have come from the asteroid belt...
就是围绕内太阳系边缘 ..the ring of rocky debris that orbits at the edge
运行的岩石残骸环带 of the inner solar system.
它很可能是在木星 And it was deflected from its orbit
引力的作用下偏离了运行轨道 most likely by the gravitational influence of Jupiter.
木星与地球是截然不同的两类行星 Jupiter is a completely different class of planet to the Earth.
它是气态巨行星 A gas giant.
一个由氢和氦组成的巨大旋涡 它的体积巨大 A swirling ball of hydrogen and helium so large
足以容纳1300个地球 you could fit 1,300 Earths inside.
木星能够对小行星产生巨大的影响 Jupiter can exert such a powerful influence on the asteroids
因为它的质量大得惊人 because it's so massive.
大约是太阳系中其它所有行星 It's about two-and-a-half times the mass of all the other planets,
卫星和小行星总质量的2.5倍 moons and asteroids in the solar system combined.
所以它能够产生巨大的引力 And, therefore, it has a strong gravitational pull.
也就是说 And this means that Jupiter exerts an influence
木星对整个太阳系的影响之大 是仅次于太阳的 across the entire solar system that's second only to the sun.
这种影响不只是制造出像这样奇怪的陨石坑 And that influenced us far more than create the odd crater.
它还能够改变行星的历史 It can change the history of worlds.
要了解木星的重要地位 To understand how Jupiter rose to such dominance,
我们必须回溯历史 甚至是太阳系诞生之前 you have to go back to a time before the solar system even existed.
50亿年前
近50亿年前 Nearly five billion years ago,
一颗遥远的恒星爆炸 在整个银河系掀起一股强烈的冲击波 a distant exploding star sent a shock wave across the galaxy...
结果导致形成太阳系的 ..causing the cloud of gas and dust
气体和尘埃云大量坍缩 that would become our solar system to collapse...
太阳由此开始形成 ..as the sun began to form.
但是在更远处 也有其它气体在逐渐聚集 But further out, something else was growing.
大约5000万年后 After 50 million years...
太阳的核熔炉燃起熊熊烈火 ..the sun's nuclear furnace ignited.
当第一束阳光洒落时 The light of its first dawn...
太阳系的第一颗行星 ..revealing Jupiter...
木星赫然呈现在眼前 ..the solar system's first world.
这颗行星诞生得很早 吸收了太阳形成过程中 A planet born so early, it swept up most of the material
留下的大部分残骸 left over from the formation of the sun.
木星凭借其优势地位 对新形成的太阳系 Because of its dominance, Jupiter had a profound effect
产生了深远影响 on the newly forming solar system
并为我们地球的诞生铺平了道路 and paved the way for our living world to form.
这是我们太阳系的模型 This is a model of our solar system.
这是太阳 然后是4个内太阳系的岩石行星 So, here's the sun, and then we have the four inner rocky planets,
包括水星 金星 地球和火星 Mercury, Venus, Earth and Mars.
接着是小行星带 Then comes the asteroid belt,
一个围绕太阳运行的 由数百万颗小块岩石 the ring of millions of smaller pieces of rock
组成的环带 orbiting around the sun.
然后是气态巨行星 And then the gas giants.
包括木星 土星 天王星和海王星 Jupiter, Saturn, Uranus and Neptune.
现在它有了一个令人满意的规则结构 Now, this has a pleasing regular structure about it.
所有岩石行星靠近太阳 All the rocky planets close to the star
气态巨行星则相距甚远 and the gas giants further out.
我们认为这应该是行星形成的自然规律 And we thought that this must be the natural order of things,
太阳系的布局上就应是这样的 the way that solar systems have to form,
可是在探测遥远恒星周围的行星后 until we started to detect planets around distant stars
我们才发现这根本不是典型的布局 and then we found that this arrangement is not typical at all.
银河系有大约3000亿颗恒星 太阳只是其中之一 Our sun is just one of around 300 billion stars in our galaxy...
几乎每颗恒星 ..and almost every one of those stars
都有自己的行星系统 is home to its own system of planets.
在其它大多数行星系统中 我们地球的公转区域是一片空旷的空间 In most other systems, the region where our planet orbits is empty.
而在更靠近恒星的地方 出现了许多“超级地球” Instead, closer to the star, we see super-Earths,
行星：波江座40B 星座：波江座 质量：8.5个地球
是比太阳系的地球更大的类地行星 vast rocky planets many times bigger than our own.
但关键在于 这些行星据估计 But, crucially, these worlds are thought
覆盖着厚厚的有毒大气 to have thick toxic atmospheres,
行星：詹森 星座：巨蟹座 大气：氢和氦
因此根本不适宜生命存在 making them completely inhospitable to life.
这就提出了一个很有意思的问题 And that raises a very interesting question.
为什么我们的太阳系是这种布局呢 Why, then, is our solar system the way that it is?
为了寻找答案 To answer that question,
我们向太阳系的所有行星都发射了探测器 we've sent spacecraft to every one of the planets...
它们已经发现的各种异常现象 ..and they've uncovered strange anomalies
揭示了我们太阳系久远的历史 that reveal our solar system's past.
金星探测器揭示 它曾经拥有的水量远远超出了 Our missions to Venus found that it once had far more water
我们对这颗近日行星的预期 than you'd expect for a planet so close to the sun...
它曾经可以匹敌地球 ..just as Earth does today.
当探测器在火星降落时 The spacecraft we've sent to Mars
眼前的世界令人大吃一惊 它的大小只有姊妹行星 touched down on a world that is curiously just half the size
地球和金星的一半大 of her sister planets Earth and Venus.
在小行星带 And in the asteroid belt,
我们发现这里是许多消亡世界的墓地 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...
因为木卫一的运行轨道 ..because Io orbits just 350,000km
距离木星的云层顶端只有35万公里 from the tops of Jupiter's clouds.
木卫一到木星的距离 Io orbits at about the same distance from Jupiter
与月亮到地球的距离差不多 as our moon orbits the Earth.
但是因为木星的质量更大 But because Jupiter is so much more massive,
木卫一的公转速度更快 Io goes around much more quickly.
事实上它每42小时就能运行一周 In fact, it goes around once every 42 hours.
如果木卫一是木星唯一的卫星 Now, if Io were Jupiter's only moon,
其运行轨道可能呈圆形 that orbit would be circular,
但并非如此 but it isn't.
美国国家航空航天局 “卡西尼”号拍摄图像
木星的第二颗卫星木卫二 每公转一周 The next moon out - Europa - goes round Jupiter precisely once
木卫一正好公转两周 for every two orbits of Io...
也就是说木卫一每公转到第二周时 ..which means that every second orbit,
就会和木卫二呈一直线 Io and Europa fall into alignment.
这就是所谓的“轨道共振” It's what's known as an orbital resonance.
在重力弹射效应的作用下 That gives it a gravitational kick
木卫一的运行轨道变成了椭圆形 and that moves Io's orbit into an ellipse.
这意味着木卫一受到的引力 Now, that means that the gravitational force's on Io
在不断变化并发生位移 are constantly shifting and changing
卫星本身不断受到拉伸挤压 and that stretches and squashes the moon,
摩擦过程就产生了热量 这被称为潮汐加热 and heats it up - by friction. Now, that is called tidal heating
也是木卫一上火山活动频繁的根源 and that is the origin of Io's volcanoes.
木卫一的地壳深处可能处于冰冻状态 This process raises the temperature in Io's interior,
潮汐加热过程使木卫一的内部温度 which would otherwise be frozen solid,
升高到了1000多摄氏度 to more than 1,000 degrees Celsius...
由此创造出了熔岩湖 ..creating its lava lakes...
还有巨大的火山羽流 ..and powering immense volcanic plumes...
它们能从木卫一表面向上喷射将近300千米 ..that rise up to 300km from the moon's surface...
最终消散在太空之中 ..and out into space.
木卫一为太阳系提供了真切的提醒 Io provides the solar system with a vivid reminder...
这颗气态巨行星威力强大 ..of the giant planet's power.
木星强大的引力场 Jupiter's intense gravitational field...
是如今木卫一火山活动的源头 ..is the source of Io's volcanism today.
但我们在地球上感受不到这股引力 But we don't feel that gravitational pull here on Earth,
是因为木星距离我们很远 because Jupiter is so far away,
可是在45亿年前 but four-and-a-half billion years ago,
木星向内太阳系不断迁移 Jupiter was migrating inwards towards the inner solar system,
渐渐逼近火星与地球即将形成的区域 approaching the region where Mars and Earth were forming.
在穿越后来会成为小行星带的区域后 After passing through what would become the asteroid belt...
木星进入了太阳系内层 ..Jupiter entered the inner solar system...
内太阳系 45亿年前
它继续以螺旋方式奔向太阳 ..continuing its journey, spiralling towards the sun.
当时 火星和地球的运行轨道附近 Back then, the area where Mars and Earth orbit today
层层密布着气体和石块 was densely packed with gas and rock.
木星靠近时造成了巨大破坏 But as Jupiter approached, it wrought havoc...
迫使岩石物质向四散各处 ..scattering the rocky material in all directions...
有些一头冲向太阳 ..some sent careering into the sun...
其它的则被抛入星际空间 ..others thrown out into interstellar space.
太阳系拥有不同寻常的行星布局 原因或许就在于此 And it's this that may explain our solar system's unusual structure.
这是如今的太阳系 Here's the solar system today.
太阳 然后是4颗岩石行星 众多小行星和木星 The sun, the four inner rocky planets, the asteroids and Jupiter.
我们认为可能发生的情形是 木星穿越了 And what we think may have happened is Jupiter made it inwards
当时小行星带的位置 最远到达了火星轨道 through where the asteroids are, as far in as the orbit of Mars.
在这个过程中它卷走了内太阳系的大量物质 And that would have cleaned out quite a lot of the material
只留下了少量物质用于行星的形成 in the inner solar system, leaving less for the formation of planets.
这就是太阳系不存在超级类地行星的原因 And that's why we don't see super-Earths in our solar system.
而在其它许多恒星周围 Those big massive rocky worlds
都有大量巨型的岩石行星 that we see in orbit around so many other stars.
这或许也能破解火星的偏小之谜了 This also might explain why Mars is so small.
如果木星当时靠近过火星形成的区域 See, if Jupiter was orbiting in the region that Mars was forming,
这里的物质自然会变少 there would have been much less material here.
这就能够解释为什么火星的质量 And that might explain why Mars
只有金星和地球质量的10%了 is only a tenth of the mass of Venus and Earth.
如果木星继续向内迁移 Had Jupiter continued to move inwards,
它很可能会对地球产生类似的影响 it would have had a similar effect on the Earth...
也就是说我们居住的地球可能永远都不会形成 ..meaning the world we inhabit might never have formed.
但就在木星看似势不可挡 长驱直入时 But just as it looked as if Jupiter would sweep everything away,
这颗气态巨行星突然遭遇了障碍 something stopped the giant planet in its tracks...
因为在太阳系外层的阴影中 ..because in the shadows of the outer solar system,
有另一颗行星正在形成 another planet was forming.
它就是太阳系中的第二颗气态巨行星 The solar system's second gas giant...
土星 ..Saturn...
土星的诞生改变了一切 ..and its birth changed everything.
当行星在恒星周围的物质盘内逐渐形成时 When a planet forms in a disk of material around a star,
就像木星在太阳系内形成时那样 as Jupiter did in our solar system,
它通常会在物质盘内清出一片空间 it tends to clear out a gap in the disk.
然后周围物质会朝向中心恒星塌陷 Now, the material tends to fall inwards towards the star.
这叫作“吸积” It's called the accretion
这会导致整个行星向内侧移动 and that drags the whole thing inwards.
木星的情况就是如此 And that's what happened to Jupiter.
但是接着一颗质量较小的行星 土星在更远处形成了 But, then, a less massive planet, Saturn, formed further out.
它也清理出自身的圆盘 It cleared out its own disk
并朝向太阳移动 and it too fell inwards towards the sun,
但速度比木星快得多 but more quickly than Jupiter.
这意味着土星与木星产生了轨道共振 That meant that Saturn got into a resonance with Jupiter.
它围绕太阳每公转一周 It went round once in orbit around the sun
木星正好公转两周 for every two orbits of Jupiter
结果导致这两颗行星间的整个空间 and that has the effect of cleaning out the whole region
都被清空了 between the two planets.
在一系列 And that has the effect,
复杂的引力相互作用下 through a series of complicated gravitational interactions,
它们的内迁速度减慢 吸积过程终止 of slowing and stopping the in-fall
两颗行星最终再次向外移动 and eventually causing the two planets to move back out again.
这就是我们太阳系中木星和土星所发生的情况 And that is what happened to Jupiter and Saturn in our solar system.
土星的出现迫使木星开始回撤 Saturn caused Jupiter to retreat...
它离开后留下的物质 ..leaving behind just enough material
勉强只够太阳系内层行星的形成 from which the inner planets could form.
它们包括水星 Mercury.
金星 Venus.
火星 Mars.
还有我们人类的家园 And our home...
地球 ..the Earth.
木星阻止了产生更大的超级类地行星 By preventing the formation of much larger super-Earths,
保障了我们地球的形成 Jupiter allowed our planet to grow.
木星在其恐怖统治即将结束时 And even as Jupiter's reign of terror was drawing to a close,
还为我们地球留下了最后的告别礼物 it provided one last parting gift to our world.
年轻的地球形成于太阳系内层的干旱地带 The young Earth formed in an arid region of the inner solar system.
靠近太阳的地方几乎没有水 There was very little water that close to the sun,
可是当地球形成时 木星已经开始向外迁移 but as the Earth was forming, Jupiter was already tacking back
返回太阳系外层 outwards again into the outer solar system
并穿过我们现在所称的小行星带 through the region that we now call the asteroid belt,
这里充斥着大量冰质 和富含水的彗星和小行星 a region populated by many icy, water rich comets and asteroids.
当木星向外迁移时 它们再次被撞飞 And they were scattered back inwards again,
把水重新带回了太阳系内层 bringing water back into the inner solar system.
这形成了一个很奇妙的理论 So, I think it is quite a wonderful thought,
地球之所以能成为“水世界” 完全要得益于这场 that Earth is a water world today because of the motion inwards
先向内后向外的木星大迁移过程 and then back outwards again of the massive planet Jupiter.
这个想法给人的感觉确实很不真实 像是天方夜谭 This idea does seem quite contrived, almost fantastical,
但当我们对太阳系的形成了解得越多 but the more we learn about the formation of solar systems,
越深入尝试建立这种 and the more we try to model a system like ours,
4颗富含水的类地行星在内 气态巨行星在外的 with four terrestrial, water-rich planets close to the star
星系布局模型时 and then the gas giants further out,
我们就越清晰地认识到或许这些事情的确发生过 the more we learn that perhaps all these things had to happen,
行星之间这些看似不可能的运动和相互作用 these unlikely movements and interactions between the planets,
最终创造出了类似太阳系 还有类似我们地球的系统 in order to produce a system like ours and a planet like ours.
所以像这样的地方可能极其罕见 So, places like this may be extremely rare.
如今木星已经进入固定轨道 Today, Jupiter has settled into a regular orbit
重新回到了小行星带的外边缘 back beyond the far edge of the asteroid belt...
它在太阳系四处劫掠的日子终于结束了 ..its days of marauding through the solar system at an end.
木星已经在固定轨道内 Jupiter has been established in a stable orbit
运行了将近40亿年 for almost four billion years.
如果在38亿年前生命刚刚诞生时 If I was to sit here on Earth 3.8 billion years ago
我坐在这里仰望夜空 when life began and look up into the night sky,
就可能会看到它跟今天一样 I would have seen it shining there as a point of light
在静谧的星空中闪耀 遥远又超然 the same as it looks today, distant and seemingly detached.
在漫长的时间里它始终未变 而地球则经历了 And it's remained that way for the vast expanse of time it's taken
自然选择的漫长进化过程 for evolution by natural selection
将最初产生的有机物变成了现在的纷繁生命 to transform those first populations of organisms into all this,
把地球变成了太阳系无垠荒漠中的 to transform the Earth into an oasis of life
一片生命绿洲 in the desert of the solar system.
但木星对地球的影响至今依然存在 But Jupiter's influence over the Earth remains to this day...
因为尽管它与地球相距甚远 鞭长莫及 ..and that's because, despite its great distance from us...
但它却牢牢掌控着小行星带 ..it retains a vice-like grip over the asteroid belt.
我们往住会很自然地 It's easy, I think quite natural,
把小行星带看作一个单一结构 to think of the asteroid belt as a single structure.
一个围绕太阳的岩石环 A sort of ring of rock surrounding the sun.
但它现在的模样并非如此 But that's not what it's like at all.
事实上 那里存在不计其数的岩石碎块 In reality, each one of those millions and millions of pieces
它们是沿着各自不同的轨道运行的 of rock is following its own individual orbits.
这段生动的模拟动画融合了 And this remarkable animation
人们10年来的天文观测结果 is made up of ten years of astronomical observations.
动画中的每个点都代表 And every point you see on this animation...
一颗小行星 也包括了所有的行星 ..is a single asteroid, apart from all the planets.
你可以看到地球 火星和金星 围绕太阳急速旋转 And so you see Earth and Mars and Venus whizzing around the sun.
但有趣的是 你看木星 But the interesting one is Jupiter...
它就在小行星带外侧公转着 ..orbiting just outside the asteroid belt.
你可以看到小行星带是跟随着 What you can see is that the asteroid belt
木星的节奏律动的 dances to Jupiter's tune.
可以说木星就是小行星带的指挥 It's the conductor of the asteroid belt, if you like.
这里有许多复杂的模式 但也有其内在结构 There are complex patterns here, but there's also structure.
产生这一切的原因就在于 And the reason for that is the delicate interplay
太阳引力和木星引力之间 between the gravitational pull of the sun
十分微妙的相互作用 and the gravitational force from Jupiter.
可能出现的情况是 Now, what can happen is that
由于两颗小行星的相互作用 perhaps because of an interaction between two asteroids,
也许是相互碰撞 perhaps they collide with each other,
也许是在各自轨道与木星排成一条直线 or perhaps on their orbit they line-up perfectly with Jupiter
由此获得额外的重力弹射 and get an extra gravitational kick,
这种结构势必会扰乱小行星的轨迹 those asteroids can be disturbed from this structure
将它们送入太阳系内层 and be sent inwards to the inner solar system.
木星正是通过这一机制实现了对靠近太阳的 And by that mechanism, Jupiter has a profound influence
几大行星的深远影响 on the planets closer to the sun.
大约一亿年前 Around 100 million years ago,
一颗直径大约10公里的小行星从小行星带被撞飞 an asteroid 10km across was ejected from the asteroid belt.
在木星引力的作用下 Dislodged by Jupiter's gravity,
它被送上一条与地球相撞的轨道 it was set on a collision course with the Earth.
小行星撞击地球形成了一团炽热的火球 When it struck, it generated a fireball so hot,
方圆1000公里内的所有生命顷刻间灰飞烟灭 anything within a 1,000km radius would have died instantly.
这次撞击导致3000亿吨硫磺 The impact threw 300 billion tonnes of sulphur
进入大气 into the atmosphere.
在接踵而至的“核冬天” And during the nuclear winter that followed,
地球上75%的物种彻底走向灭绝 75% of all species were wiped from the face of the Earth.
强大的木星 In one fell swoop,
一下改变了地球的历史进程 Jupiter changed the course of our planet's history.
如今在地球上几个地方 There are a few places on Earth today
仍旧能看到这些失落世界的影子 where you can catch a glimpse of lost worlds,
那里看起来仍像数百万年前的地球 you can see Earth as it was millions of years in the past
可以一睹地球曾经的模样 and perhaps glimpse the Earth as it might have been.
这里就是其中一个去处 And this is one of them.
这里现在是美国科罗拉多平原 Today, this is the Colorado Plain,
海拔超过1000米 over a kilometre in altitude,
位于丹佛市以南 靠近落基山脉 south of Denver close to the Rocky Mountains,
可是如果在两亿年前 这里处于海平面高度 but 200 million years ago, this was at sea level.
是一个古老的湖泊 而那些失落世界的幽灵 It was an ancient lake and the ghosts of those lost worlds,
那些过去的印记仍能看到 the imprints of the past, can be seen over there,
因为在这里能发现成千上万的恐龙脚印 because there are literally thousands of dinosaur footprints.
这些就是恐龙的脚印 And here they are, the dinosaur footprints.
感觉这真的很不可思议 I find this absolutely remarkable.
这些是大型的蜥脚类恐龙脚印 This is the footprint of a sauropod dinosaur.
它属于大型食草恐龙 脖子很长 That's one of the big ones. The big herbivores with the long necks.
它们重量在30吨左右 This animal would have weighed about 30 tonnes.
身高差不多有两层楼那么高 It was tall enough to peer over a two-storey house.
我们可以想象的是 当时可能有一群蜥脚类恐龙 What happened here is, probably a herd of them, a group of them
行动笨拙地穿越湖床 随后 came lumbering across this lake bed and, then,
也许就在当天下午 紧盯这群恐龙的 perhaps that same afternoon, predators came,
捕食者尾随而来 maybe following the herd.
这些脚印就是异特龙留下 And that's these footprints here.
这是三趾脚印 The allosaurus', these three-toed footprints.
异特龙的体形要小得多 大概是我身高的两倍 Much smaller animal, maybe about twice the height of me,
体重大约两吨 非常灵活敏捷 about two tonnes, very nimble and agile.
你在这里相当于看到了一个被时间冻结的完整故事 So, you see a whole story played out here, frozen in time.
如今的地球上只留下了它们的脚印 Today, just their traces remain...
但如果不是木星的缘故 ..but were it not for Jupiter...
它们或许依旧倘佯在地球各处 ..they might still be here.
在漫长的地球历史上 There are so many chance events,
甚至是长达138亿年的宇宙历史上 not only throughout the history of Earth,
发生过许多偶然事件 but also spanning the entire history of the universe
如果没有这些偶然事件 我们可能根本不存在 for 13.8 billion years, without which we wouldn't exist.
地球生命自从40亿年前诞生以来 There's an unbroken chain of life stretching back
就始终繁衍延续 four billion years here on this planet.
如果中间出现任何中断或干扰 You interrupt or interject at any point
地球生命就会发生变化 and life on Earth is different.
当然就像所提到的 还会有一些影响生命的重大事件发生 But having said that, there are major events that affected life.
其中之一就是小行星的撞击导致了恐龙的灭绝 And one of them is the asteroid that wipes out the dinosaurs.
从这个意义上我们可以说 And, in that sense, it is certainly true to say
如果没有木星 人类就不可能存在 that without Jupiter, we wouldn't be here.
这位太阳系的守护者冥冥之中为人类统治地球 The godfather of the planets paved the way for us
铺平了道路 to inherit the Earth.
虽然它偶尔还是会从小行星带 And although it occasionally flings rocks
向我们抛掷几颗石块 from the asteroid belt our way...
但它也在保护着我们 ..it also protects us...
对于那些从太阳系最远 ..because for objects heading towards the Earth
冲向地球的天体来说 from the far reaches of the solar system,
木星的引力场发挥着屏障般的作用 Jupiter's gravitational field acts as a shield.
大约100年前 一颗直径4000米 Around a century ago, a lump of rock and ice
重170亿吨 由岩石和冰组成的彗星 4km across and weighing 17 billion tonnes...
朝着太阳系内层猛冲过来 ..was hurtling towards the inner solar system...
此时木星大显威力 ..until Jupiter intervened.
5 4 3 2 1 Five, four, three, two, one...
我们已经点火并发射“亚特兰蒂斯”号 We have ignition and lift off of Atlantis
搭载“伽利略”号前往木星 and the Galileo Spacecraft bound for Jupiter.
70年后 我们亲眼目睹了木星的 70 years later, we witnessed just how effective a shield
有效屏障作用 Jupiter can be.
美国国家航空航天局 “亚特兰蒂斯”号航天飞机 1989年
“亚特兰蒂斯”号航天飞机搭载的是 Onboard the space shuttle Atlantis...
“伽利略”号轨道探测器 ..the Galileo orbiter.
苏梅克-列维9号彗星
在“伽利略”号探测器发射3年后 Three years after Galileo launched,
苏梅克列维9号彗星被木星的引力俘获 comet Shoemaker-Levy-9 had been captured by Jupiter's gravity.
它落入了这颗气态巨行星的怀抱 Locked in the giant planet's embrace...
并在潮汐力的作用下变得四分五裂 ..tidal forces now began to tear it apart.
这颗彗星的旅程戛然而止 Its journey cut short...
等待它的是毁灭的结局 ..the comet now faced annihilation.
1994年7月 距离木星2.4亿公里
“伽利略”号飞出内太阳系 After crossing the inner solar system,
穿过小行星带 Galileo passed through the asteroid belt...
逐渐接近即将见证这颗彗星 ..approaching the spots from where it would witness
最后毁灭的地方 the comet's final moments.
美国国家航空航天局 “伽利略”号拍摄图像
7月16日 “伽利略”号观测到这颗彗星的首批碎片 On July 16th, Galileo saw the first fragments of the comet
落入了木星的南半球 enter Jupiter's southern hemisphere.
苏梅克列维9号彗星的碎片 Pieces of comet Shoemaker-Levy-9
撞击木星的过程持续了6天时间 struck Jupiter over the course of six days.
这是人类第一次直接观测到彗星撞击事件 It was the first time a comet strike had ever been witnessed.
这次最具破坏性的撞击产生的威力 The most destructive impact released energy
相当于6万亿吨TNT炸药的当量 equivalent to six million megatons of TNT...
由此造成了直径12000公里的巨大黑云层 ..leaving behind a giant dark cloud 12,000km across.
通过俘获天体并以撞击方式将其焚毁 By capturing objects and incinerating them on impact...
木星成功清除了那些可能撞击地球的 ..Jupiter sweeps up bodies from the outer solar system...
来自太阳系之外的天体 ..that might otherwise collide with Earth.
木星 Jupiter,
这颗最古老 最大的行星 the oldest and largest of the planets,
是我们太阳系的守护者 is the godfather of our solar system.
它在年轻时 In youth...
喜欢横冲直撞 ..it went on the rampage.
它给一些年轻行星带来了灭顶之灾 For some young planets, it spelt disaster.
但同时它为另一些行星 But for others, like our own world,
比如地球的形成扫除了障碍 it cleared the way for their formation.
成年的木星为我们人类在地球的崛起 And in adulthood, it created the conditions
创造了条件 that allowed us to rise...
所以我们欠了木星一份大人情 ..so we owe Jupiter a great debt.
但是在恐龙付出沉重代价后 But as the dinosaurs found to their cost,
我们才发现木星随时都可能向我们讨债 it's a debt that could be recalled at any time.
我们用肉眼看上去 To the naked eye,
木星是夜空中最亮的星星之一 Jupiter is one of the brightest points of light in the night sky,
在小望远镜里它是美丽的带状世界 and through a small telescope, it is a beautiful banded world.
但它看起来即遥远又永恒 But it feels distant, eternal,
仿佛与各种地球事件毫不相关 disconnected from events here on Earth.
但我们对太阳系的历史了解得越多 But the more we've understood about the history of the solar system,
就越能理解事实并非如此 the more we've come to understand that that is not the case.
木星在包括地球在内的所有行星故事中 Jupiter has played an important and perhaps decisive role
扮演着非常重要甚至是决定性角色 in the stories of all the planets, including Earth.
太阳系就是这样一个错综复杂 So, the solar system is just that. It's a system.
相互联系而又相互依存的系统 Complex, interconnected and interdependent.
所以下次你看到木星时 So, next time you see Jupiter, just hold your gaze.
就多端详它一会 因为它不仅是个亮点 Maybe think for a minute, because it is so much more than just a point
一颗行星 of light, or a planet, even.
它是太阳系伟大的雕塑家 It is the great sculptor of the solar system,
这个世界的毁灭者和创造者 the destroyer and creator of worlds.
《行星》幕后故事
我觉得木星之所以迷人 I think people are drawn in by Jupiter
就在于它很神秘 because it's very mysterious.
海蒂·贝克 “朱诺”号任务科学家
厚厚的云层掩盖了它表面的一切 It's covered by clouds that hide what's underneath.
它是一颗狂暴 It's very violent.
令人畏惧的行星 And it's very intimidating.
它也很漂亮 It's also very beautiful.
而且所有事件都在这里发生 It has all these things going on
很难不被它吸引 and it's hard not to be taken in.
倒计时 10 9 8 7 6 5 T-minus ten, nine, eight, seven, six...
正是木星的神秘莫测 Such is Jupiter's mystique,
才让人们一直将其作为太空探索的目标 it's been a recurring target for space exploration.
发射升空 “朱诺”号前往木星 And lift off of the Atlas V with Juno on a trek to Jupiter.
2011年 美国国家航空航天局发射“朱诺”号执行一项新太空任务 In 2011, Nasa launched its latest mission - Juno.
美国国家航空航天局 “朱诺”号探测器
我们当初从地球向木星 When we launched the Juno spacecraft
发射“朱诺”号探测器时 away from the Earth out towards Jupiter,
它自身的飞行速度根本不足以让它摆脱太阳的引力 we didn't have enough speed to get away out of the gravity of the sun,
弗朗·巴格纳尔教授 “朱诺”号任务科学家
我们只能让它重返地球 so we actually had to come back to Earth,
在地球引力的弹射作用下获得速度增量 get a gravity assist from Earth,
然后再飞往木星 and then go out to Jupiter.
经过5年的长途旅行 “朱诺”号终于进入环木星轨道 After travelling for five years, Juno finally arrived.
这次木星探测任务是有史以来 This is a mission that goes closer to the planet in its orbit
最靠近木星的 than any other mission ever has.
距离木星的云层顶端只有几千公里 它的速度非常非常快 Only a few thousand kilometres from the cloud tops and very, very fast.
在两个小时内就完成两极间移动 We go from pole to pole in two hours,
划过云层顶部的辐射带 slipping between the radiation belts in the cloud tops,
尽快获取数据 然后离开 getting the data as fast as we can and getting out.
所以从各方面来说 “朱诺”号都是开创性的 So, in every way, Juno is breaking new ground
它让我们看到了许多无法想象的事情 and that's allowed us to see things that we couldn't have ever imagined.
“朱诺”号的使命就是对木星展开全面深入的探索 Juno's mission is to explore the planets inside and out.
它携带的科学仪器中 And amongst the many scientific instruments it has on board
包含朱诺相机 is its camera, JunoCam.
我们看到了所有那些旋涡 还有各种斑点 You see all these swirls, you see all sorts of spots coming up.
可以看到所有这些旋涡 我们还看到相互作用的剧烈风暴系统 You see all these vortices, you see dramatic storm systems interacting.
这台小照相机拍摄的图像 It's mind-blowingly beautiful pictures
简直美得令人震撼 that this little camera has been taking.
朱诺相机从上方近距离拍到了大红斑 JunoCam was able to see the Great Red Spot from up close.
我们能看到云层的高度 We can see height to the clouds.
也能看到酷似风暴的特征 We can see features that look like storms.
木星上也许正在下冰雹或者下氨雪 Maybe it's hailing or snowing ammonia on Jupiter.
在朱诺相机拍到的图像中最令人吃惊的 And the most startling thing that we saw from JunoCam's imagery
就是木星的两极其实是蓝色的 was that the poles of Jupiter are actually blue.
它和我们小时候想象中的 They are nothing like the orange and white planet
橙白相间的星球截然不同 that we grew up thinking about as children.
“朱诺”号探测器才刚刚开始破解木星的秘密 Juno has just begun to unlock Jupiter's secrets.
这位太阳系的守护者 And so, at last,
终于向我们敞开了心扉 the godfather of the planets has begun to talk.
下集预告
一颗在诞生时期并不起眼的岩石星球 A planet that began life as an unremarkable rocky world...
却转变成太阳系里的一颗明珠 ..but transformed into one of the jewels of the solar system...
在它闪耀的冰环里或许隐藏着生命的潜在家园 ..where shimmering rings of ice harbour a potential home for life.
土星 Saturn.
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