美國國家航空航天局「信使」號水星探測器發射升空 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
沿著內太陽系向外 Beyond the inner solar system...
穿過小行星帶 ..past the asteroid belt...
木星便映入眼簾 ..lies Jupiter.
木星 距離太陽7.8億公里
它是太陽系中體積最大的行星 一顆氣態巨行星 The largest of the planets is a giant swirling ball of gas...
它表面斑駁的花紋是肆虐的風暴 ..its marbled appearance generated by violent winds
經過木星雲層時形成的 that rage through its clouds.
木星是一個既陌生又遙遠的世界 Jupiter is a world as strange as it is remote.
如果你向上空飛行大約100千米左右 If you fly upwards, only about 100km or so,
你就能到達大氣層邊緣和漆黑的太空 you reach the edge of our atmosphere and the blackness of space.
距離並不遙遠 It's really not that far.
可一旦置身太空 But once you're in space,
衡量距離的尺度就變得超乎想像 the distance scales are sort of incomprehensible.
金星是距離地球最近的行星 大約為4000萬公里 I mean, Venus, the closest planet, is over 40 million kilometres away.
木星離地球大約為6.5億公里 Jupiter around 650 million kilometres.
飛行最快的探測器也要數年才能到達 It takes our fastest spacecraft years to get there.
所以其它行星可能會影響地球 So, the idea that those planets could have any influence on us
人類的想法似乎有些異想天開 here on Earth seems fanciful.
事實上 如果你說的是 And, indeed, if you're talking about
遇到陌生帥哥的幾率 your chances of meeting a handsome stranger
或者需要在週三時調整未來一周的生活安排 or your life plans requiring a moderate reconfiguration
那確實不會有影響 about a week on Wednesday, then you would be right.
但是如果要涉及到更深刻 更深層次的問題 However, if you ask more profound questions, deeper questions like,
比如地球為什麼是這樣 "Why is the Earth the way that it is?
地球上為何存在生命 "Why is there life on Earth?
人類為何存在 "Why do we exist at all?"
那麼事實證明這些行星 特別是木星 then it turns out that the planets, and Jupiter in particular,
對地球具有深遠影響 have had a profound effect.
在生命初期 年輕的木星就開始橫衝直撞 Early in its life, the young Jupiter went on the rampage.
這顆氣態巨行星開始了穿越太陽系的 The giant planet embarked on a voyage of destruction
毀滅之旅 across the solar system...
它改寫了太陽系各大行星的命運 ..that transformed the destiny of the planets,
改變了地球上的生命歷程 and the course of life on Earth.
木星是太陽系的守護者 Jupiter is the godfather of the planets.
對木星的探測研究有助於我們瞭解整個太陽系的形成 Understand it and you understand how the solar system came to be.
教父 木星
在地球上 我們能夠一瞥木星的巨大威力 On Earth, we can see glimpses of Jupiter's power...
這些就是它在地球表面 ..in the scars it's left...
留下的傷疤 ..on the face of the planet.
這是美國亞利桑那州的巴林傑隕石坑 This is the famous Barringer Meteor Crater in Arizona.
它的直徑大約是1000米 It is about a kilometre across,
從火山口邊緣到底部深170米 170 metres from the rim to the crater floor
大約5萬年前 and it was created about 50,000 years ago
一顆直徑50米的隕石以每秒13公里的速度 when a meteorite, 50 metres across, entered the Earth's atmosphere
撞入地球大氣層 travelling at about 13km per second.
這就意味著它從進入地球大氣層 That means it would have taken around, what, seven seconds
到落地的時間大約需要7秒鐘 to go from the top of the atmosphere to the ground
它撞擊地球的力度很大 釋放出的能量相當於 and it hit with such force that the energy released
1000萬噸炸藥爆炸的當量 was equivalent to ten megatons of TNT.
它就像一枚巨大的核彈 And that is a very large nuclear bomb.
科學界認為 The meteorite that hit the Earth here
這顆撞擊地球的隕石來自小行星帶 is thought to have come from the asteroid belt...
就是圍繞內太陽系邊緣 ..the ring of rocky debris that orbits at the edge
運行的岩石殘骸環帶 of the inner solar system.
它很可能是在木星 And it was deflected from its orbit
引力的作用下偏離了運行軌道 most likely by the gravitational influence of Jupiter.
木星與地球是截然不同的兩類行星 Jupiter is a completely different class of planet to the Earth.
它是氣態巨行星 A gas giant.
一個由氫和氦組成的巨大漩渦 它的體積巨大 A swirling ball of hydrogen and helium so large
足以容納1300個地球 you could fit 1,300 Earths inside.
木星能夠對小行星產生巨大的影響 Jupiter can exert such a powerful influence on the asteroids
因為它的質量大得驚人 because it's so massive.
大約是太陽系中其它所有行星 It's about two-and-a-half times the mass of all the other planets,
衛星和小行星總質量的2.5倍 moons and asteroids in the solar system combined.
所以它能夠產生巨大的引力 And, therefore, it has a strong gravitational pull.
也就是說 And this means that Jupiter exerts an influence
木星對整個太陽系的影響之大 是僅次於太陽的 across the entire solar system that's second only to the sun.
這種影響不只是製造出像這樣奇怪的隕石坑 And that influenced us far more than create the odd crater.
它還能夠改變行星的歷史 It can change the history of worlds.
要瞭解木星的重要地位 To understand how Jupiter rose to such dominance,
我們必須回溯歷史 甚至是太陽系誕生之前 you have to go back to a time before the solar system even existed.
50億年前
近50億年前 Nearly five billion years ago,
一顆遙遠的恆星爆炸 在整個銀河系掀起一股強烈的衝擊波 a distant exploding star sent a shock wave across the galaxy...
結果導致形成太陽系的 ..causing the cloud of gas and dust
氣體和塵埃雲大量坍縮 that would become our solar system to collapse...
太陽由此開始形成 ..as the sun began to form.
但是在更遠處 也有其它氣體在逐漸聚集 But further out, something else was growing.
大約5000萬年後 After 50 million years...
太陽的核熔爐燃起熊熊烈火 ..the sun's nuclear furnace ignited.
當第一束陽光灑落時 The light of its first dawn...
太陽系的第一顆行星 ..revealing Jupiter...
木星赫然呈現在眼前 ..the solar system's first world.
這顆行星誕生得很早 吸收了太陽形成過程中 A planet born so early, it swept up most of the material
留下的大部分殘骸 left over from the formation of the sun.
木星憑借其優勢地位 對新形成的太陽系 Because of its dominance, Jupiter had a profound effect
產生了深遠影響 on the newly forming solar system
並為我們地球的誕生鋪平了道路 and paved the way for our living world to form.
這是我們太陽系的模型 This is a model of our solar system.
這是太陽 然後是4個內太陽系的岩石行星 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.
接著是小行星帶 Then comes the asteroid belt,
一個圍繞太陽運行的 由數百萬顆小塊岩石 the ring of millions of smaller pieces of rock
組成的環帶 orbiting around the sun.
然後是氣態巨行星 And then the gas giants.
包括木星 土星 天王星和海王星 Jupiter, Saturn, Uranus and Neptune.
現在它有了一個令人滿意的規則結構 Now, this has a pleasing regular structure about it.
所有岩石行星靠近太陽 All the rocky planets close to the star
氣態巨行星則相距甚遠 and the gas giants further out.
我們認為這應該是行星形成的自然規律 And we thought that this must be the natural order of things,
太陽系的佈局上就應是這樣的 the way that solar systems have to form,
可是在探測遙遠恆星周圍的行星後 until we started to detect planets around distant stars
我們才發現這根本不是典型的佈局 and then we found that this arrangement is not typical at all.
銀河系有大約3000億顆恆星 太陽只是其中之一 Our sun is just one of around 300 billion stars in our galaxy...
幾乎每顆恆星 ..and almost every one of those stars
都有自己的行星系統 is home to its own system of planets.
在其它大多數行星系統中 我們地球的公轉區域是一片空曠的空間 In most other systems, the region where our planet orbits is empty.
而在更靠近恆星的地方 出現了許多「超級地球」 Instead, closer to the star, we see super-Earths,
行星：波江座40B 星座：波江座 質量：8.5個地球
是比太陽系的地球更大的類地行星 vast rocky planets many times bigger than our own.
但關鍵在於 這些行星據估計 But, crucially, these worlds are thought
覆蓋著厚厚的有毒大氣 to have thick toxic atmospheres,
行星：詹森 星座：巨蟹座 大氣：氫和氦
因此根本不適宜生命存在 making them completely inhospitable to life.
這就提出了一個很有意思的問題 And that raises a very interesting question.
為什麼我們的太陽系是這種佈局呢 Why, then, is our solar system the way that it is?
為了尋找答案 To answer that question,
我們向太陽系的所有行星都發射了探測器 we've sent spacecraft to every one of the planets...
它們已經發現的各種異常現象 ..and they've uncovered strange anomalies
揭示了我們太陽系久遠的歷史 that reveal our solar system's past.
金星探測器揭示 它曾經擁有的水量遠遠超出了 Our missions to Venus found that it once had far more water
我們對這顆近日行星的預期 than you'd expect for a planet so close to the sun...
它曾經可以匹敵地球 ..just as Earth does today.
當探測器在火星降落時 The spacecraft we've sent to Mars
眼前的世界令人大吃一驚 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.
在小行星帶 And in the asteroid belt,
我們發現這裏是許多消亡世界的墓地 we've uncovered a graveyard of failed worlds...
它們在形成時遭到了神秘的打斷 ..their growth mysteriously cut short.
據說所有這些異常現象 To cause all these anomalies,
很可能是太陽系誕生初期發生的 it's thought that something catastrophic must have happened
某個災難性事件造成的 very early in the solar system's history.
所有證據表明大約45億年前 All the evidence suggests that around 4.5 billion years ago,
木星軌道開始發生移動 Jupiter's orbit began to change,
由此引發了一段前所未見的狂暴時期 triggering a period of unprecedented violence
徹底改變了年輕太陽系的面貌 which completely transformed the face of the young solar system.
我們知道這點 是因為這顆四處掠奪的行星 And we know this because the marauding planet
留下了一連串的毀滅痕跡 left a trail of destruction in its wake.
木星在其生命早期 開始向內太陽系移動 Early in its life, Jupiter began to move inwards towards the sun...
這種內向遷移的影響至今仍清晰可見 ..and the effects of that journey can be seen to this day.
小行星帶 現在
小行星帶位於火星和木星的 In between the orbits of Mars and Jupiter...
軌道之間 ..lies the asteroid belt...
它是一片充斥著 ..a desolate wasteland of debris
太陽系形成初期殘留碎片的荒蕪之地 left over from the beginning of the solar system.
這些岩石星體個頭太小 本身無法成為行星 Rocky bodies too small to be planets in their own right.
科幻電影中經常把小行星帶描繪成 In science fiction films, the asteroid belt is often depicted
一堆無法通航的翻滾碎石 as an un-navigable mass of tumbling rubble.
但事實並非如此 But it's not like that at all.
事實上 現代探測器能夠 So much so, in fact, that modern spacecraft engineers
在無需修正航線的情況下 順利穿過小行星帶 can fly a spacecraft through without making any course corrections.
原因就在於小行星帶的物質非常稀薄 The reason for that is there's not much mass in the asteroid belt.
所有這些小行星的質量總和只有月球質量的4%左右 A sum total of all of them is only about 4% the mass of the moon
而且它們廣泛分佈在 and they're spread out in a huge sort of ring,
火星軌道外的巨大圓環內 所佔的空間十分廣闊 out beyond the orbit of Mars. So, it's a vast amount of space.
這意味著任何兩顆大型小行星間的平均距離 That means that the average distance between any two large asteroids
大約是地球和月球之間距離的8倍 is about eight times the distance between the Earth and the moon.
所以我可以站在一顆巨型小行星上 So, I could stand on one of those large asteroids
遠眺太空 and look out into space
我最近的鄰居可能只是黑暗中一顆暗淡的星星 and my nearest neighbour would just be a dim star in the dark.
但是散落在小行星帶的 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 主發動機啟動 1 0 two, main engine start, one, zero and lift off
美國國家航空航天局 「黎明」號探測器
德爾塔二號火箭升空 of the Delta II Rocket.
2007年 美國國家航空航天局的「黎明」號探測器 In 2007, Nasa's Dawn mission
前往小行星帶探索最大的兩顆小行星 was sent to explore the two largest objects in the asteroid belt.
在環繞巨型小行星灶神星運行一年後 After a year in orbit around the giant asteroid Vesta...
2015年3月 ..in March 2015...
「黎明」號探測器最終靠近這顆質量 ..Dawn made its final approach on a body so large
超過整個小行星帶三分之一的巨大天體 it makes up almost a third of the mass of the entire asteroid belt...
谷神星 ..Ceres.
「黎明」號傳回地球的第一批照片 On arrival, the first images Dawn sent back to Earth
包含一個完全出人意料的發現 contained something entirely unexpected...
美國國家航空航天局 「黎明」號拍攝圖像
谷神星最大的一個隕石坑中存在神秘的亮斑 ..mysterious bright patches in one of Ceres' largest craters.
這些照片的光譜分析結果顯示 Spectral analysis of the images
這些亮斑其實是 showed that the patches were, in fact,
液態水留下的鹽漬 the salty residue left behind by liquid water...
這說明它的地殼深處可能隱藏著 ..suggesting there must be large amounts of ice
大量的水冰 just beneath the crust.
「黎明」號探測器隨後發現谷神星地表存在300多個亮點 Dawn went on to discover over 300 bright spots all over the surface.
這說明在薄薄的地殼下 And this means that beneath this thin crust,
谷神星的岩石內核周圍是厚厚的 富含水冰的地幔層 Ceres has a thick ice rich mantle surrounding its rocky core...
換句話說 這顆矮行星存在分層結構 ..evidence that the dwarf planet is made up of multiple layers.
谷神星的內部與小行星帶的其它任何天體都不同 The interior of Ceres is like nothing else in the asteroid belt.
「黎明」號所發現的這種分層結構 The differentiation, that separation into layers, observed by Dawn
更像是行星 而不是小行星的特徵 is more characteristic of a planet than an asteroid.
所以45億年前 谷神星正處於 So, 4.5 billion years ago, Ceres was well on its way
成熟醞釀階段 to becoming a fully-fledged world.
谷神星 45億年前
據說谷神星在嬰兒時期就表現得與眾不同 It's thought that's in its infancy Ceres was very different.
如今凍結在其內部的水冰曾經是大量的液態水 The water that now lies frozen within its interior was once liquid.
表面僅有一層薄冰覆蓋 Protected beneath a thin layer of ice...
谷神星可能曾擁有遍佈全球的咸水海洋 ..Ceres was once covered by a deep saltwater ocean.
谷神星還沒來得及釋放潛能 Before Ceres had reached its full potential,
一場巨型騷動引發的衝擊波 a great disturbance sent shock waves through
穿過後來的小行星帶襲來 what would one day become the asteroid belt
使它的成長戛然而止 and cut its development short.
小行星帶 45億年前
木星在圍繞年輕的太陽公轉時 As Jupiter circled the young sun,
一路披荊斬棘 在覆蓋早期太陽系的氣體和塵埃中 it started to clear a path through the gas and dust
清理出了一條通道 that shrouded the early solar system...
這個過程中它的表現令人擔憂 ..but that process caused it to do something alarming.
它與這些氣體的相互引力作用 使這顆氣態巨行星 Gravitational interactions with the gas made the giant planets
向著太陽內側呈螺旋運動 spiral inwards towards the sun...
它直接穿過後來成為 ..ploughing straight through the region of space
小行星帶的空間區域 that would become the asteroid belt...
將谷神星原本積蓄的形成物質 ..scattering the material from which Ceres
徹底擊散 would otherwise have grown.
早期太陽系的計算機模擬結果顯示 Computer simulations of the early solar system
小行星帶曾經獲得了足夠物質 suggest that the asteroid belt once contained enough material
來形成一個地球大小的行星 to build a planet the size of the Earth.
那也許曾經是谷神星的命運 And perhaps that was Ceres's destiny.
可是當木星經過時 But when Jupiter passed through,
它99.9%的形成物質都散失到了太空中 it scattered 99.9% of the material away,
谷神星的命運已然注定 and Ceres's fate was sealed.
在之後的一億年裏 谷神星的海洋完全凍結 Within 100 million years, Ceres's ocean froze
並深埋於地殼之下 and was buried beneath its crust.
這顆年輕的行星還沒等踐行諾言 The young planet's development cut short
生命的腳步就夏然而止 before it could fulfil its promise.
但是木星的恐怖統治還遠遠沒有結束 But Jupiter's reign of terror was far from over.
它繼續向著太陽內側 It would continue its journey inwards
朝我們地球即將形成的地方前進 towards the place our planet was beginning to form...
嚴重威脅地球的存在 ..threatening the very existence of Earth.
木星憑借其強大的引力場對年輕的太陽系 Jupiter had such an overwhelming effect on the young solar system
產生了震憾性的影響 because of its powerful gravitational field...
這些影響至今仍舊清晰可見 ..the effects of which we can still witness today.
木星通過它的引力場對整個太陽系 Jupiter exerts its influence across the solar system
施加了影響 through its gravitational field...
它是迄今為止所有行星中最強大的一顆 ..which is by far the most powerful of all the planets,
因為木星在所有行星中質量最大 because Jupiter is the most massive of all the planets.
大約是地球質量的320倍 It's about 320 times the mass of the Earth.
這就是它產生驚人破壞力的原因所在 That's why it was so destructive in the past.
如今 我們可以看到它的引力場 And we see the power of that gravitational field today
對木星最近的衛星木衛一的影響 in its influence on the closest of Jupiter's largest moons, Io.
木衛一 現在
木衛一是太陽系中火山活動最活躍的星球 Io is the most volcanic world in the solar system.
它的表面覆蓋著成百上千座活火山 Its surface covered with hundreds of active volcanoes...
還有眾多的熔岩湖 ..and lakes of molten lava.
其中最大的熔岩湖名為洛基火山口 The largest, known as Loki Patera,
直徑超過了200公里 is more than 200km in diameter.
是地球上任何熔岩湖面積的100萬倍 A million times the area of any lava lake on Earth.
四處流竄的熔岩流不斷侵襲著木衛一的表面 Its surface tormented by waves of molten rock.
這裏儼然就是人間地獄 Io is a vision of hell...
而始作俑者就是強大的木星引力 ..created by the moon's proximity to Jupiter.
地球上所有火山活動的能量都來自地下深處的 Volcanism here on Earth is powered by the internal heat
內部熱量 down below the surface.
現在這些地熱 Now, much of that is residual heat
大約有一半來自 left over from the Earth's formation
45億年前地球形成時產生的餘熱 另一半則來自 four-and-a-half billion years ago, about half of it, and the other half
地核周圍各種化學元素的放射性衰變 is down to radioactive decay of elements around the Earth's core.
然而 木衛一的情況卻截然不同 Now, on Io it's different.
它是一顆較小的衛星 Io's a much smaller world
肯定不會保留太多餘熱 and so it didn't retain much residual heat.
所以木衛一的火山能量來自不同的過程 So, there, the volcanoes are powered by a different process.
就是所謂的「潮汐加熱」 It's known as tidal heating.
在木衛一上驅動火山活動的 The energy that drives Io's volcanism
並非衛星內部的熱能 doesn't come from heat stored within the moon.
而是引力作用 It's generated by gravity...
因為木衛一的運行軌道 ..because Io orbits just 350,000km
距離木星的雲層頂端只有35萬公里 from the tops of Jupiter's clouds.
木衛一到木星的距離 Io orbits at about the same distance from Jupiter
與月亮到地球的距離差不多 as our moon orbits the Earth.
但是因為木星的質量更大 But because Jupiter is so much more massive,
木衛一的公轉速度更快 Io goes around much more quickly.
事實上它每42小時就能運行一周 In fact, it goes around once every 42 hours.
如果木衛一是木星唯一的衛星 Now, if Io were Jupiter's only moon,
其運行軌道可能呈圓形 that orbit would be circular,
但並非如此 but it isn't.
美國國家航空航天局 「卡西尼」號拍攝圖像
木星的第二顆衛星木衛二 每公轉一周 The next moon out - Europa - goes round Jupiter precisely once
木衛一正好公轉兩周 for every two orbits of Io...
也就是說木衛一每公轉到第二周時 ..which means that every second orbit,
就會和木衛二呈一直線 Io and Europa fall into alignment.
這就是所謂的「軌道共振」 It's what's known as an orbital resonance.
在重力彈射效應的作用下 That gives it a gravitational kick
木衛一的運行軌道變成了橢圓形 and that moves Io's orbit into an ellipse.
這意味著木衛一受到的引力 Now, that means that the gravitational force's on Io
在不斷變化並發生位移 are constantly shifting and changing
衛星本身不斷受到拉伸擠壓 and that stretches and squashes the moon,
摩擦過程就產生了熱量 這被稱為潮汐加熱 and heats it up - by friction. Now, that is called tidal heating
也是木衛一上火山活動頻繁的根源 and that is the origin of Io's volcanoes.
木衛一的地殼深處可能處於冰凍狀態 This process raises the temperature in Io's interior,
潮汐加熱過程使木衛一的內部溫度 which would otherwise be frozen solid,
升高到了1000多攝氏度 to more than 1,000 degrees Celsius...
由此創造出了熔岩湖 ..creating its lava lakes...
還有巨大的火山羽流 ..and powering immense volcanic plumes...
它們能從木衛一表面向上噴射將近300千米 ..that rise up to 300km from the moon's surface...
最終消散在太空之中 ..and out into space.
木衛一為太陽系提供了真切的提醒 Io provides the solar system with a vivid reminder...
這顆氣態巨行星威力強大 ..of the giant planet's power.
木星強大的引力場 Jupiter's intense gravitational field...
是如今木衛一火山活動的源頭 ..is the source of Io's volcanism today.
但我們在地球上感受不到這股引力 But we don't feel that gravitational pull here on Earth,
是因為木星距離我們很遠 because Jupiter is so far away,
可是在45億年前 but four-and-a-half billion years ago,
木星向內太陽系不斷遷移 Jupiter was migrating inwards towards the inner solar system,
漸漸逼近火星與地球即將形成的區域 approaching the region where Mars and Earth were forming.
在穿越後來會成為小行星帶的區域後 After passing through what would become the asteroid belt...
木星進入了太陽系內層 ..Jupiter entered the inner solar system...
內太陽系 45億年前
它繼續以螺旋方式奔向太陽 ..continuing its journey, spiralling towards the sun.
當時 火星和地球的運行軌道附近 Back then, the area where Mars and Earth orbit today
層層密佈著氣體和石塊 was densely packed with gas and rock.
木星靠近時造成了巨大破壞 But as Jupiter approached, it wrought havoc...
迫使岩石物質向四散各處 ..scattering the rocky material in all directions...
有些一頭衝向太陽 ..some sent careering into the sun...
其它的則被拋入星際空間 ..others thrown out into interstellar space.
太陽系擁有不同尋常的行星佈局 原因或許就在於此 And it's this that may explain our solar system's unusual structure.
這是如今的太陽系 Here's the solar system today.
太陽 然後是4顆岩石行星 眾多小行星和木星 The sun, the four inner rocky planets, the asteroids and Jupiter.
我們認為可能發生的情形是 木星穿越了 And what we think may have happened is Jupiter made it inwards
當時小行星帶的位置 最遠到達了火星軌道 through where the asteroids are, as far in as the orbit of Mars.
在這個過程中它捲走了內太陽系的大量物質 And that would have cleaned out quite a lot of the material
只留下了少量物質用於行星的形成 in the inner solar system, leaving less for the formation of planets.
這就是太陽系不存在超級類地行星的原因 And that's why we don't see super-Earths in our solar system.
而在其它許多恆星周圍 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.
這或許也能破解火星的偏小之謎了 This also might explain why Mars is so small.
如果木星當時靠近過火星形成的區域 See, if Jupiter was orbiting in the region that Mars was forming,
這裏的物質自然會變少 there would have been much less material here.
這就能夠解釋為什麼火星的質量 And that might explain why Mars
只有金星和地球質量的10%了 is only a tenth of the mass of Venus and Earth.
如果木星繼續向內遷移 Had Jupiter continued to move inwards,
它很可能會對地球產生類似的影響 it would have had a similar effect on the Earth...
也就是說我們居住的地球可能永遠都不會形成 ..meaning the world we inhabit might never have formed.
但就在木星看似勢不可擋 長驅直入時 But just as it looked as if Jupiter would sweep everything away,
這顆氣態巨行星突然遭遇了障礙 something stopped the giant planet in its tracks...
因為在太陽系外層的陰影中 ..because in the shadows of the outer solar system,
有另一顆行星正在形成 another planet was forming.
它就是太陽系中的第二顆氣態巨行星 The solar system's second gas giant...
土星 ..Saturn...
土星的誕生改變了一切 ..and its birth changed everything.
當行星在恆星周圍的物質盤內逐漸形成時 When a planet forms in a disk of material around a star,
就像木星在太陽系內形成時那樣 as Jupiter did in our solar system,
它通常會在物質盤內清出一片空間 it tends to clear out a gap in the disk.
然後周圍物質會朝向中心恆星塌陷 Now, the material tends to fall inwards towards the star.
這叫作「吸積」 It's called the accretion
這會導致整個行星向內側移動 and that drags the whole thing inwards.
木星的情況就是如此 And that's what happened to Jupiter.
但是接著一顆質量較小的行星 土星在更遠處形成了 But, then, a less massive planet, Saturn, formed further out.
它也清理出自身的圓盤 It cleared out its own disk
並朝向太陽移動 and it too fell inwards towards the sun,
但速度比木星快得多 but more quickly than Jupiter.
這意味著土星與木星產生了軌道共振 That meant that Saturn got into a resonance with Jupiter.
它圍繞太陽每公轉一周 It went round once in orbit around the sun
木星正好公轉兩周 for every two orbits of Jupiter
結果導致這兩顆行星間的整個空間 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,
複雜的引力相互作用下 through a series of complicated gravitational interactions,
它們的內遷速度減慢 吸積過程終止 of slowing and stopping the in-fall
兩顆行星最終再次向外移動 and eventually causing the two planets to move back out again.
這就是我們太陽系中木星和土星所發生的情況 And that is what happened to Jupiter and Saturn in our solar system.
土星的出現迫使木星開始回撤 Saturn caused Jupiter to retreat...
它離開後留下的物質 ..leaving behind just enough material
勉強只夠太陽系內層行星的形成 from which the inner planets could form.
它們包括水星 Mercury.
金星 Venus.
火星 Mars.
還有我們人類的家園 And our home...
地球 ..the Earth.
木星阻止了產生更大的超級類地行星 By preventing the formation of much larger super-Earths,
保障了我們地球的形成 Jupiter allowed our planet to grow.
木星在其恐怖統治即將結束時 And even as Jupiter's reign of terror was drawing to a close,
還為我們地球留下了最後的告別禮物 it provided one last parting gift to our world.
年輕的地球形成於太陽系內層的乾旱地帶 The young Earth formed in an arid region of the inner solar system.
靠近太陽的地方幾乎沒有水 There was very little water that close to the sun,
可是當地球形成時 木星已經開始向外遷移 but as the Earth was forming, Jupiter was already tacking back
返回太陽系外層 outwards again into the outer solar system
並穿過我們現在所稱的小行星帶 through the region that we now call the asteroid belt,
這裏充斥著大量冰質 和富含水的彗星和小行星 a region populated by many icy, water rich comets and asteroids.
當木星向外遷移時 它們再次被撞飛 And they were scattered back inwards again,
把水重新帶回了太陽系內層 bringing water back into the inner solar system.
這形成了一個很奇妙的理論 So, I think it is quite a wonderful thought,
地球之所以能成為「水世界」 完全要得益於這場 that Earth is a water world today because of the motion inwards
先向內後向外的木星大遷移過程 and then back outwards again of the massive planet Jupiter.
這個想法給人的感覺確實很不真實 像是天方夜譚 This idea does seem quite contrived, almost fantastical,
但當我們對太陽系的形成瞭解得越多 but the more we learn about the formation of solar systems,
越深入嘗試建立這種 and the more we try to model a system like ours,
4顆富含水的類地行星在內 氣態巨行星在外的 with four terrestrial, water-rich planets close to the star
星系佈局模型時 and then the gas giants further out,
我們就越清晰地認識到或許這些事情的確發生過 the more we learn that perhaps all these things had to happen,
行星之間這些看似不可能的運動和相互作用 these unlikely movements and interactions between the planets,
最終創造出了類似太陽系 還有類似我們地球的系統 in order to produce a system like ours and a planet like ours.
所以像這樣的地方可能極其罕見 So, places like this may be extremely rare.
如今木星已經進入固定軌道 Today, Jupiter has settled into a regular orbit
重新回到了小行星帶的外邊緣 back beyond the far edge of the asteroid belt...
它在太陽系四處劫掠的日子終於結束了 ..its days of marauding through the solar system at an end.
木星已經在固定軌道內 Jupiter has been established in a stable orbit
運行了將近40億年 for almost four billion years.
如果在38億年前生命剛剛誕生時 If I was to sit here on Earth 3.8 billion years ago
我坐在這裏仰望夜空 when life began and look up into the night sky,
就可能會看到它跟今天一樣 I would have seen it shining there as a point of light
在靜謐的星空中閃耀 遙遠又超然 the same as it looks today, distant and seemingly detached.
在漫長的時間裏它始終未變 而地球則經歷了 And it's remained that way for the vast expanse of time it's taken
自然選擇的漫長進化過程 for evolution by natural selection
將最初產生的有機物變成了現在的紛繁生命 to transform those first populations of organisms into all this,
把地球變成了太陽系無垠荒漠中的 to transform the Earth into an oasis of life
一片生命綠洲 in the desert of the solar system.
但木星對地球的影響至今依然存在 But Jupiter's influence over the Earth remains to this day...
因為儘管它與地球相距甚遠 鞭長莫及 ..and that's because, despite its great distance from us...
但它卻牢牢掌控著小行星帶 ..it retains a vice-like grip over the asteroid belt.
我們往住會很自然地 It's easy, I think quite natural,
把小行星帶看作一個單一結構 to think of the asteroid belt as a single structure.
一個圍繞太陽的岩石環 A sort of ring of rock surrounding the sun.
但它現在的模樣並非如此 But that's not what it's like at all.
事實上 那裏存在不計其數的岩石碎塊 In reality, each one of those millions and millions of pieces
它們是沿著各自不同的軌道運行的 of rock is following its own individual orbits.
這段生動的模擬動畫融合了 And this remarkable animation
人們10年來的天文觀測結果 is made up of ten years of astronomical observations.
動畫中的每個點都代表 And every point you see on this animation...
一顆小行星 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 圍繞太陽急速旋轉 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...
它就在小行星帶外側公轉著 ..orbiting just outside the asteroid belt.
你可以看到小行星帶是跟隨著 What you can see is that the asteroid belt
木星的節奏律動的 dances to Jupiter's tune.
可以說木星就是小行星帶的指揮 It's the conductor of the asteroid belt, if you like.
這裏有許多複雜的模式 但也有其內在結構 There are complex patterns here, but there's also structure.
產生這一切的原因就在於 And the reason for that is the delicate interplay
太陽引力和木星引力之間 between the gravitational pull of the sun
十分微妙的相互作用 and the gravitational force from Jupiter.
可能出現的情況是 Now, what can happen is that
由於兩顆小行星的相互作用 perhaps because of an interaction between two asteroids,
也許是相互碰撞 perhaps they collide with each other,
也許是在各自軌道與木星排成一條直線 or perhaps on their orbit they line-up perfectly with Jupiter
由此獲得額外的重力彈射 and get an extra gravitational kick,
這種結構勢必會擾亂小行星的軌跡 those asteroids can be disturbed from this structure
將它們送入太陽系內層 and be sent inwards to the inner solar system.
木星正是通過這一機制實現了對靠近太陽的 And by that mechanism, Jupiter has a profound influence
幾大行星的深遠影響 on the planets closer to the sun.
大約一億年前 Around 100 million years ago,
一顆直徑大約10公里的小行星從小行星帶被撞飛 an asteroid 10km across was ejected from the asteroid belt.
在木星引力的作用下 Dislodged by Jupiter's gravity,
它被送上一條與地球相撞的軌道 it was set on a collision course with the Earth.
小行星撞擊地球形成了一團熾熱的火球 When it struck, it generated a fireball so hot,
方圓1000公里內的所有生命頃刻間灰飛煙滅 anything within a 1,000km radius would have died instantly.
這次撞擊導致3000億噸硫磺 The impact threw 300 billion tonnes of sulphur
進入大氣 into the atmosphere.
在接踵而至的「核冬天」 And during the nuclear winter that followed,
地球上75%的物種徹底走向滅絕 75% of all species were wiped from the face of the Earth.
強大的木星 In one fell swoop,
一下改變了地球的歷史進程 Jupiter changed the course of our planet's history.
如今在地球上幾個地方 There are a few places on Earth today
仍舊能看到這些失落世界的影子 where you can catch a glimpse of lost worlds,
那裏看起來仍像數百萬年前的地球 you can see Earth as it was millions of years in the past
可以一睹地球曾經的模樣 and perhaps glimpse the Earth as it might have been.
這裏就是其中一個去處 And this is one of them.
這裏現在是美國科羅拉多平原 Today, this is the Colorado Plain,
海拔超過1000米 over a kilometre in altitude,
位於丹佛市以南 靠近落基山脈 south of Denver close to the Rocky Mountains,
可是如果在兩億年前 這裏處於海平面高度 but 200 million years ago, this was at sea level.
是一個古老的湖泊 而那些失落世界的幽靈 It was an ancient lake and the ghosts of those lost worlds,
那些過去的印記仍能看到 the imprints of the past, can be seen over there,
因為在這裏能發現成千上萬的恐龍腳印 because there are literally thousands of dinosaur footprints.
這些就是恐龍的腳印 And here they are, the dinosaur footprints.
感覺這真的很不可思議 I find this absolutely remarkable.
這些是大型的蜥腳類恐龍腳印 This is the footprint of a sauropod dinosaur.
它屬於大型食草恐龍 脖子很長 That's one of the big ones. The big herbivores with the long necks.
它們重量在30噸左右 This animal would have weighed about 30 tonnes.
身高差不多有兩層樓那麼高 It was tall enough to peer over a two-storey house.
我們可以想像的是 當時可能有一群蜥腳類恐龍 What happened here is, probably a herd of them, a group of them
行動笨拙地穿越湖床 隨後 came lumbering across this lake bed and, then,
也許就在當天下午 緊盯這群恐龍的 perhaps that same afternoon, predators came,
捕食者尾隨而來 maybe following the herd.
這些腳印就是異特龍留下 And that's these footprints here.
這是三趾腳印 The allosaurus', these three-toed footprints.
異特龍的體形要小得多 大概是我身高的兩倍 Much smaller animal, maybe about twice the height of me,
體重大約兩噸 非常靈活敏捷 about two tonnes, very nimble and agile.
你在這裏相當於看到了一個被時間凍結的完整故事 So, you see a whole story played out here, frozen in time.
如今的地球上只留下了它們的腳印 Today, just their traces remain...
但如果不是木星的緣故 ..but were it not for Jupiter...
它們或許依舊倘佯在地球各處 ..they might still be here.
在漫長的地球歷史上 There are so many chance events,
甚至是長達138億年的宇宙歷史上 not only throughout the history of Earth,
發生過許多偶然事件 but also spanning the entire history of the universe
如果沒有這些偶然事件 我們可能根本不存在 for 13.8 billion years, without which we wouldn't exist.
地球生命自從40億年前誕生以來 There's an unbroken chain of life stretching back
就始終繁衍延續 four billion years here on this planet.
如果中間出現任何中斷或干擾 You interrupt or interject at any point
地球生命就會發生變化 and life on Earth is different.
當然就像所提到的 還會有一些影響生命的重大事件發生 But having said that, there are major events that affected life.
其中之一就是小行星的撞擊導致了恐龍的滅絕 And one of them is the asteroid that wipes out the dinosaurs.
從這個意義上我們可以說 And, in that sense, it is certainly true to say
如果沒有木星 人類就不可能存在 that without Jupiter, we wouldn't be here.
這位太陽系的守護者冥冥之中為人類統治地球 The godfather of the planets paved the way for us
鋪平了道路 to inherit the Earth.
雖然它偶爾還是會從小行星帶 And although it occasionally flings rocks
向我們拋擲幾顆石塊 from the asteroid belt our way...
但它也在保護著我們 ..it also protects us...
對於那些從太陽系最遠 ..because for objects heading towards the Earth
衝向地球的天體來說 from the far reaches of the solar system,
木星的引力場發揮著屏障般的作用 Jupiter's gravitational field acts as a shield.
大約100年前 一顆直徑4000米 Around a century ago, a lump of rock and ice
重170億噸 由岩石和冰組成的彗星 4km across and weighing 17 billion tonnes...
朝著太陽系內層猛衝過來 ..was hurtling towards the inner solar system...
此時木星大顯威力 ..until Jupiter intervened.
5 4 3 2 1 Five, four, three, two, one...
我們已經點火並發射「亞特蘭蒂斯」號 We have ignition and lift off of Atlantis
搭載「伽利略」號前往木星 and the Galileo Spacecraft bound for Jupiter.
70年後 我們親眼目睹了木星的 70 years later, we witnessed just how effective a shield
有效屏障作用 Jupiter can be.
美國國家航空航天局 「亞特蘭蒂斯」號航天飛機 1989年
「亞特蘭蒂斯」號航天飛機搭載的是 Onboard the space shuttle Atlantis...
「伽利略」號軌道探測器 ..the Galileo orbiter.
蘇梅克-列維9號彗星
在「伽利略」號探測器發射3年後 Three years after Galileo launched,
蘇梅克列維9號彗星被木星的引力俘獲 comet Shoemaker-Levy-9 had been captured by Jupiter's gravity.
它落入了這顆氣態巨行星的懷抱 Locked in the giant planet's embrace...
並在潮汐力的作用下變得四分五裂 ..tidal forces now began to tear it apart.
這顆彗星的旅程戛然而止 Its journey cut short...
等待它的是毀滅的結局 ..the comet now faced annihilation.
1994年7月 距離木星2.4億公里
「伽利略」號飛出內太陽系 After crossing the inner solar system,
穿過小行星帶 Galileo passed through the asteroid belt...
逐漸接近即將見證這顆彗星 ..approaching the spots from where it would witness
最後毀滅的地方 the comet's final moments.
美國國家航空航天局 「伽利略」號拍攝圖像
7月16日 「伽利略」號觀測到這顆彗星的首批碎片 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.
蘇梅克列維9號彗星的碎片 Pieces of comet Shoemaker-Levy-9
撞擊木星的過程持續了6天時間 struck Jupiter over the course of six days.
這是人類第一次直接觀測到彗星撞擊事件 It was the first time a comet strike had ever been witnessed.
這次最具破壞性的撞擊產生的威力 The most destructive impact released energy
相當於6萬億噸TNT炸藥的當量 equivalent to six million megatons of TNT...
由此造成了直徑12000公里的巨大黑雲層 ..leaving behind a giant dark cloud 12,000km across.
通過俘獲天體並以撞擊方式將其焚燬 By capturing objects and incinerating them on impact...
木星成功清除了那些可能撞擊地球的 ..Jupiter sweeps up bodies from the outer solar system...
來自太陽系之外的天體 ..that might otherwise collide with Earth.
木星 Jupiter,
這顆最古老 最大的行星 the oldest and largest of the planets,
是我們太陽系的守護者 is the godfather of our solar system.
它在年輕時 In youth...
喜歡橫衝直撞 ..it went on the rampage.
它給一些年輕行星帶來了滅頂之災 For some young planets, it spelt disaster.
但同時它為另一些行星 But for others, like our own world,
比如地球的形成掃除了障礙 it cleared the way for their formation.
成年的木星為我們人類在地球的崛起 And in adulthood, it created the conditions
創造了條件 that allowed us to rise...
所以我們欠了木星一份大人情 ..so we owe Jupiter a great debt.
但是在恐龍付出沉重代價後 But as the dinosaurs found to their cost,
我們才發現木星隨時都可能向我們討債 it's a debt that could be recalled at any time.
我們用肉眼看上去 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,
在小望遠鏡裏它是美麗的帶狀世界 and through a small telescope, it is a beautiful banded world.
但它看起來即遙遠又永恆 But it feels distant, eternal,
彷彿與各種地球事件毫不相關 disconnected from events here on Earth.
但我們對太陽系的歷史瞭解得越多 But the more we've understood about the history of the solar system,
就越能理解事實並非如此 the more we've come to understand that that is not the case.
木星在包括地球在內的所有行星故事中 Jupiter has played an important and perhaps decisive role
扮演著非常重要甚至是決定性角色 in the stories of all the planets, including Earth.
太陽系就是這樣一個錯綜複雜 So, the solar system is just that. It's a system.
相互聯繫而又相互依存的系統 Complex, interconnected and interdependent.
所以下次你看到木星時 So, next time you see Jupiter, just hold your gaze.
就多端詳它一會 因為它不僅是個亮點 Maybe think for a minute, because it is so much more than just a point
一顆行星 of light, or a planet, even.
它是太陽系偉大的雕塑家 It is the great sculptor of the solar system,
這個世界的毀滅者和創造者 the destroyer and creator of worlds.
《行星》幕後故事
我覺得木星之所以迷人 I think people are drawn in by Jupiter
就在於它很神秘 because it's very mysterious.
海蒂·貝克 「朱諾」號任務科學家
厚厚的雲層掩蓋了它表面的一切 It's covered by clouds that hide what's underneath.
它是一顆狂暴 It's very violent.
令人畏懼的行星 And it's very intimidating.
它也很漂亮 It's also very beautiful.
而且所有事件都在這裏發生 It has all these things going on
很難不被它吸引 and it's hard not to be taken in.
倒計時 10 9 8 7 6 5 T-minus ten, nine, eight, seven, six...
正是木星的神秘莫測 Such is Jupiter's mystique,
才讓人們一直將其作為太空探索的目標 it's been a recurring target for space exploration.
發射升空 「朱諾」號前往木星 And lift off of the Atlas V with Juno on a trek to Jupiter.
2011年 美國國家航空航天局發射「朱諾」號執行一項新太空任務 In 2011, Nasa launched its latest mission - Juno.
美國國家航空航天局 「朱諾」號探測器
我們當初從地球向木星 When we launched the Juno spacecraft
發射「朱諾」號探測器時 away from the Earth out towards Jupiter,
它自身的飛行速度根本不足以讓它擺脫太陽的引力 we didn't have enough speed to get away out of the gravity of the sun,
弗朗·巴格納爾教授 「朱諾」號任務科學家
我們只能讓它重返地球 so we actually had to come back to Earth,
在地球引力的彈射作用下獲得速度增量 get a gravity assist from Earth,
然後再飛往木星 and then go out to Jupiter.
經過5年的長途旅行 「朱諾」號終於進入環木星軌道 After travelling for five years, Juno finally arrived.
這次木星探測任務是有史以來 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.
距離木星的雲層頂端只有幾千公里 它的速度非常非常快 Only a few thousand kilometres from the cloud tops and very, very fast.
在兩個小時內就完成兩極間移動 We go from pole to pole in two hours,
劃過雲層頂部的輻射帶 slipping between the radiation belts in the cloud tops,
盡快獲取數據 然後離開 getting the data as fast as we can and getting out.
所以從各方面來說 「朱諾」號都是開創性的 So, in every way, Juno is breaking new ground
它讓我們看到了許多無法想像的事情 and that's allowed us to see things that we couldn't have ever imagined.
「朱諾」號的使命就是對木星展開全面深入的探索 Juno's mission is to explore the planets inside and out.
它攜帶的科學儀器中 And amongst the many scientific instruments it has on board
包含朱諾相機 is its camera, JunoCam.
我們看到了所有那些漩渦 還有各種斑點 You see all these swirls, you see all sorts of spots coming up.
可以看到所有這些漩渦 我們還看到相互作用的劇烈風暴系統 You see all these vortices, you see dramatic storm systems interacting.
這台小照相機拍攝的圖像 It's mind-blowingly beautiful pictures
簡直美得令人震撼 that this little camera has been taking.
朱諾相機從上方近距離拍到了大紅斑 JunoCam was able to see the Great Red Spot from up close.
我們能看到雲層的高度 We can see height to the clouds.
也能看到酷似風暴的特徵 We can see features that look like storms.
木星上也許正在下冰雹或者下氨雪 Maybe it's hailing or snowing ammonia on Jupiter.
在朱諾相機拍到的圖像中最令人吃驚的 And the most startling thing that we saw from JunoCam's imagery
就是木星的兩極其實是藍色的 was that the poles of Jupiter are actually blue.
它和我們小時候想像中的 They are nothing like the orange and white planet
橙白相間的星球截然不同 that we grew up thinking about as children.
「朱諾」號探測器才剛剛開始破解木星的秘密 Juno has just begun to unlock Jupiter's secrets.
這位太陽系的守護者 And so, at last,
終於向我們敞開了心扉 the godfather of the planets has begun to talk.
下集預告
一顆在誕生時期並不起眼的岩石星球 A planet that began life as an unremarkable rocky world...
卻轉變成太陽系里的一顆明珠 ..but transformed into one of the jewels of the solar system...
在它閃耀的冰環裏或許隱藏著生命的潛在家園 ..where shimmering rings of ice harbour a potential home for life.
土星 Saturn.
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