了解宇宙是如何运行的（2010）

and then move it in
由此我们想到各种问题
and this had us asking all kinds of questions
如果其他星系有这种现象
if we see it going on elsewhere in the universe
我们的太阳系是不是也有？
is that how our own solar system worked, too?
现在 我们看着木星
so now, when we look at jupiter
我们对他木星的位置觉得是理所当然的
we think, all right, that's where it is today
但这并不意味着它一直都在那里
but it doesn't mean it's always been there
它有可能运动到各个地方
it could have moved all over the place
最后刚好停在现在
and it just ended up where it is
这个位置
where we find it today
问题是这颗气体巨行星是怎么来到现在的位置的？
the question is how how did this giant planet end up where it is today?
木星的运动又对其他行星有着什么影响？
and what effect did a migrating jupiter have on the other planets?
在2011年 沃尔什和他的团队模拟了太阳系的形成
in 2011, walsh and his team re-imagined the solar system
他们让木星四处漂移
they set jupiter adrift, and in the process
并在此过程中解开了太阳系的一个大谜团
they solve one of the solar system's greatest puzzles
我们使用模型进行模拟
we would build our models, would get a venus
结果金星会出现在现在的位置
right where the venus is supposed to be
地球也会出现在现在的位置
would get an earth right where the earth is supposed to be
但我们模拟的火星
but where mars is today
质量和金星或地球差不多
we were usually getting a venus or earth-massed planet
不管我们怎么改变模型
no matter what we did, no matter how we changed the model
都会模拟出一个超大的火星
we were always getting a really big mars
根据我们所有的模拟
all of our simulation
在原盘里的火星
showed that mars, where it is in the disk
质量至少是今日火星的十倍
should be at least ten times the mass that it is
一定是有人吃掉了火星的那份食物
something came in and literally ate mars' lunch
罪魁祸首就是木星
and that something was jupiter
45亿年前
four and a half billion years ago
木星形成 距离太阳有3.25亿英里（约5.23亿公里）
jupiter forms 325 million miles from the sun
比今日的距离短了三分之一左右
oughly a third closer than it is today
木星在运行时
the orbiting planet collides
撞上太阳形成后所留下的碎屑
with the debris left over from the sun's formation
这些撞击使得木星减速
and these collisions slow it down
木星失去动量
it loses momentum
并被太阳的引力拉近
and the sun's gravity pulls it closer
木星一边自转
jupiter spirals inwards
一边往太阳系内漂移 并吞掉了原本属于火星的物质
gobbling up the raw materials that should have made mars
火星为何会这么小的答案
so, seeing that result, seeing a great solution
其实是意外发现的
to the small mars problem was kind of the eureka moment
我们想 这也许是某种机制♥造♥成的
like, well, maybe there's a mechanism out there
既然行星会移♥动♥
we know that planets migrate
我们就把这个因素也一起考虑
so, let's put these two things together
或许会找到答案
and maybe this is going to work
木星向内移♥动♥时
as jupiter travels inwards
会推动前方的岩石物质
it bulldozes the rocky material that lies in its path
木星向内移♥动♥时 前方有很多物质
on the inward migration, there's a lot of material there
其中近八成的物质被往内推
it actually pushes almost all of that about 80 % of it, inward
在我们做出的模拟动画里
and when we make the movies in a certain way
木星某种程度上来看就像是铲雪车
it really looks like a snowplow
气体和尘埃压缩成
the gas and dust squeeze
环绕太阳系内部的圆盘
into an inner disk around the sun
木星运行时
as jupiter orbits
将圆盘挤出一块膨胀区
it pushes against this disk, creating a bulge
这块膨胀区会拖着木星沿着圆盘边缘移♥动♥
the bulge races round the disk, pulling jupiter with it
木星想要挣脱太阳的引力
jupiter accelerates and tries to pull away from the sun
但是木星后方的碎屑却继续往内推
but the debris behind jupiter continues pushing inwards
木星陷入了极大的僵局
it's a cosmic stalemate
它被困在内外两方的琐屑圆盘之间
with the planet trapped between the inner and outer disks
接着发生了不可思议的现象
then, something extraordinary happens
巨大的木星改变了方向
the giant planet changes direction
我们在建立这个模型时
as we're building this model
便推测木星会往内移♥动♥
we've had this vision of jupiter coming inwards
然后转向 向外移♥动♥
turning around and going outwards
就像帆船一样
and we thought of it as a sailboat
它会受风的影响 掉头然后改变航向
kind of tacking, coming about, turning through the wind
所以 大航向模型这个名字
so, the name the grand tack model
来自航海术语
it actually comes from sailing terminology
但是木星不是游艇
but jupiter is no yacht
而是个超级巨大的行星
it's a giant supertanker of a planet
要有十分强大的力量
changing its course is going to take something
才能改变它的运行方向
seriously powerful
此时 太阳系的第二大行星 土星登场了
enter the solar system's second largest planet saturn
和木星一样
like jupiter before it
土星也在向内运动 两者的距离越来越近
aturn has spiraled inwards, closing in on the giant planet
不可思议的是木星和土星在互相影响
amazingly, there was this wonderful interplay between jupiter and saturn
它们吞没了周围的所有物质
as they ate up all the material around them
于是圆盘出现了缺口
there was a gap in the disk left over
木星和土星后方的物质越来越少
with less material behind jupiter and saturn
牵制它们的引力就随着减弱
there's less holding the planets in place
结果膨胀圆盘的力量
allowing the force from the bulging disk
将木星往外甩
to fling jupiter back out
土星也跟着飞出去
with saturn hitching a ride
大航向模型中阻止木星向内移♥动♥的关键所在
the key for stopping jupiter's inward migration
就是土星
in the grand tack is saturn
土星形成的时间和地点恰好可以让它
saturn growing at the right time and at the right place
靠近木星并改变木星的方向
allowed it to migrate close to jupiter and change
阻止木星向内运动
and stop jupiter's inward migration
土星让木星免遭被烧毁的命运
saturn saves jupiter from a fiery fate
大航向漂移留下了一份赠别礼物 那就是地球
and this grand tack leaves a parting gift, the earth itself
木星向外运动的时候
because when jupiter migrates out
被它推动的岩石碎屑便留在原处
it leaves behind the rocky debris it bulldozed in
地球就诞生于这些碎屑中
it's from this debris that the earth forms
但是在火星以外的地带 木星的引力会吸引碎屑
but beyond mars, jupiter's powerful gravity
由此碎屑无法凝聚
pulls on the debris, preventing it from sticking together
只能四处散布 形成小行星带
leaving the rubble scattered as a band of asteroids
木星的引力如此强大 以至于它可以在某些方面
jupiter's gravity is so strong that it determines in some ways
决定什么天体可以在太阳系的何处形成 什么不可以
what can exist where in the solar system and what can't
像是岩石行星
the rocky planets
我们的地球
our planet
还有火星和以外的小行星带
and beyond mars the asteroid belt
都源自木星的伟大旅程
they all exist because of jupiter's epic journey
太阳系中最大的行星
when the biggest thing in the solar system
高速运动到远处
is moving this far this fast
它会改变周围的一切
it changes everything around it
木星在形成的500万年后
five million years after it first formed
它移♥动♥到我们现在观测到的轨道上
483 million miles from the sun jupiter reaches its present orbit
它的外移运动
its outward movement
和太阳的引力终于达成为妙的平衡
and the inward pull of the sun's gravity are finally balanced
但是这时的太阳系任然和我们现在的有所不同
but this is still not the solar system that we see today
大航向漂移的终点
the end point of the grand tack model
为太阳系的历史
was actually the ideal beginnings
写下了完美的序章
of what we think happened ater on in solar system history
但从这个稳定的轨道
but from this stable orbit
引发致命的多米诺骨牌效应
jupiter is about to trigger a deadly domino effect
让初生的地球面临夭折的危机
that threatens to destroy the infant earth
45亿年前
four and a half billion years ago
木星在岩石内行星
jupiter orbits between the rocky inner planets
和冰质外行星之间运行
and the icy outer planets
木星处于最有利的位置
from this strategic vantage point
这颗气体巨行星主宰着我们的行星系统
the gas giant dominates our planetary system
并引发地狱般的灾难
and unleashes hell
在太阳系刚形成时
in the early environment of the solar system
地球和太阳系周围的岩石碎屑
where there was a lot more junk surrounding the earth
比现在多很多
and in the inner solar system, the earth was bombarded
当时的地球和其他行星不断受到高速撞击
as were all other objects, at an incredible rate
这是一段在太阳系历史上 非常狂暴猛烈的时期
it's an incredibly violent time in solar system history
对于太阳系行星形成的几亿年后的时间段
we refer to that timescale about several hundred million years
我们有个专门的名称
after the planets actually formed
叫做“后期重轰炸期”
as the late heavy bombardment
这些都是大规模的撞击
these were very large-scale impacts
这些撞击使得产生的陨石坑的岩石