追逐冥王星（2015）

像冥王星，地球，木星，外星球这种星体
that objects like Pluto,the Earth,Jupiter,exoplanets
会以非常多样化的型态
come in a remarkable variety
和非常不同的结构布局
and in remarkably different configurations
存在于整个宇宙中
across the universe.
虽然冥王星不再是太阳系的第九颗行星
While Pluto may no longer be the solar system's ninth planet,
但它却多了很多伙伴
it turns out it's got plenty of company.
行星科学家继续发现更多矮行星
Planetary scientists continue to discover more dwarf planets,
并给它们取了暂时性的小名
giving them temporary nicknames
例如“圣诞老公公”或“复活节兔”
like "Santa" and "Easterbunny."
我们发现外太阳系里，到处都是小行星
We've discovered that the outer solar system is littered with small planets.
主要是一些岩石和冰组成的物体
These are typically rocky and icy objects.
其中许多具有大气层
Many have atmospheres.
可能大多数也拥有月球
Many,possibly most,have moons.
我们熟悉的行星所拥有的，它们也都有
All the things we're used to in the planets we're familiar with,
只是规模比较迷你
but in miniature.
我觉得可以拿吉娃娃狗做个比喻
I think a decent analogy is when you see a Chihuahua,
它确实是一只狗
it's still a dog
因为它具有狗这个物种的所有特征
because it has the characteristics of the canine species,
只不过很迷你
just in miniature.
不是所有人都同意艾伦史登拿狗做的比喻
Not everyone agrees with Alan Stern's canine analogy,
随着更多古柏带星体被发现
and as more Kuiper Belt objects are discovered,
问题出现了
the question arises:
外太阳系为什么会有这么多小侏星?
how did our outer solar system end up with these pint-sized dwarfs?
为了回答这个问题
To answer that,we may need to look back
我们可能需要回头看太阳系的肇始
at the birth of the solar system.
我们认为太阳系是在
We think that the solar system began to form
45到46亿年前开始形成
about 4.5 to 4.6 billion years ago
当时一个星云
when a cloud of nebula,
也就是气体和灰尘组成的云雾
a cloud of gas and dust,
因为自己的重力而塌缩
fell in on itself because of its own gravity.
星云在塌缩过程中变成
As it fell together,
绕着轨道旋转的巨大圆盘状物质
it began to turn into a great disc of orbiting,swirling material.
我们认为就是这个气体和灰尘组成的圆盘
It's that disc of gas and dust that we
逐渐演变成行星
think turns into planets.
物质慢慢黏结起来
You make a planet from material
变成越来越大的物体
sticking together and building larger
行星就形成了
and larger pieces.
科学家的理论是
Scientists theorize that
这个物质开始黏结以后
planets form when this material
行星就逐渐形成
starts to stick together.
小石头变成大石头
Pebbles turn into boulders,
大石头变成大山般的彗星
boulders into mountain-sized comets.
彗星变成原行星
Comets turn into protoplanets.
原行星变成行星
Protoplanets turn into planets.
物体质量达到某个门坎以后
After objects reach a certain threshold in their mass,
就会比以前增大得更快
they can grow more rapidly than they could before
因为它有了比较大的重力
because they have substantial gravity.
木星和土星等巨大气态星体
Gas giants like Jupiter and Saturn siphoned up
吸收大量的氢和氦
massive amounts of hydrogen and helium,
扫除周围的一切
sweeping up everything in sight.
我们可以合理推断
It seems plausible that Pluto
冥王星原本形成于比较接近太阳的位置
originally formed somewhat closer in to the Sun,
但随着那些大行星越来越巨大
but then as those major planets got larger and larger,
冥王星被挤到比较遥远的轨道
it got pushed to a more distant orbit.
我们认为冥王星和古柏带的其他物体
We think that objects like Pluto and the other Kuiper Belt bodies
其实是那个星球形成过程的残余物
are really the remains of that process of planet formation.
这些物体有时被称为微行星
They are sometimes called planetesimals,
因为某种原因不再成长的天体
celestial objects that somehow stopped growing.
矮行圣在行星成长过程中期，停止发展
Dwarf planets were arrested in the mid-stage of planetary growth.
它其实就像行星的胚胎
They are actually planetary embryos.
研究这些小型物体
And to study those objects
会比研究长成巨大规模的物体
rather than objects that grew to much larger scales
更能让我们进一步了解行星的形成过程
will give us a great window into the process of planetary formation.
或许我们可以在冥王星表面及它的组成中
Perhaps we can find clues in the surface of Pluto
找到一些关于那个遥远历史的线索
and its composition that point towards that deep history
让这些线索带领我们探索
and in turn tell us about the architecture
太阳系的现有架构
of the solar system as it is now.
它是怎么来的?
Where did that come from?
那一切是怎么发生的？
How did that happen?
冥王星甚至可能含有线索
Pluto may even hold clues
可供解开另一个大秘密
to unravel another great mystery.
就我们所知
As far as we know,the requirements for
生命的必要条件是水、能量和有机物质
life are water,energy,and organic matter.
许多矮行星可能拥有这所有成分
A large number of dwarf planets may have all of these ingredients.
有些著名的冥王星模型
There are very reputable models of Pluto
显示它的内部有巨大的海洋
that suggest that there's a vast interior ocean
而这可能普遍存在于其他矮行星
and that these may be common inside the dwarf planets.
只要有水，就会有生物存在的潜力
Wherever you have water,then you have the potential--
我特别强调潜力这个词
and I want to stress that word,"potential"-- for biology.
所以也许矮行星
So it may be that the dwarf planets
不只是太阳系中
are not only the most common kind of planet
最普遍的行星
in the solar system,
它可能是太阳系中最普遍的生命存在处所
they may be the most common abode for life in the solar system.
显然有机化学和碳化学作用
Clearly,organic chemistry,carbon chemistry
可能发生在彗星之类的物体表面
can take place on the surface of objects like comets
古柏带物体的表面也很有可能
and probably Kuiper Belt objects too.
这跟地球上的生命存在是否有关
Whether or not that relates to the existence of life on Earth
我认为是个完全开放的问题
I think is a totally open question.
但如果能了解太阳系及宇宙的化学丰富性
But just understanding the chemical richness of our solar system and the universe
就等于找到拼图的一大块
is a big piece of the puzzle,
而这一块是我们现在需要解决的部分
and it's a piece of the puzzle that we need to solve.
2008年6月8日
June 8,2008.
新视野号♥的太空航行已经超过两年
New Horizons has been soaring through space for more than two years.
今天它通过土星轨道
Today,it passes the orbit of Saturn.
再过三年它通过天王星
In three more years,it passes Uranus.
它已经在太空中航行五年
It's spent half a decade traveling through space,
依然如时钟般精准地往前移♥动♥
and it's still running like clockwork.
然后发生了意料之外的事
But then the unexpected happens,
使整个任务陷入危险
putting the entire mission at risk.
哈伯太空望远镜拍摄的影像
Images taken by the Hubble Space
显示冥王星的月亮不是只有一个
Telescope reveal Pluto has not one,
也不是两个，三个或四个
not two,not three,not four,
而是五个
but five moons.
这些月亮很可能都形成于同一次巨大宇宙撞击
All of these moons probably all formed in the same big cosmic collision taking place
发生时间是46亿年前
about 4.6 billion years ago,
两颗冥王星大小的物体对撞
where two Pluto-sized objects rammed into each other,
我们现在看到的是那次撞击的后果
and now we're seeing the aftermath of that.
撞击之后冥王星维持原状
In the end,Pluto remained intact,
但另一个星体破成碎块
but the other object broke into pieces,
形成我们所知的五个月球
forming the five moons that we know of,
其中有些形状非常怪
some very oddly shaped.
这些小月球都是“碎片产生器”
All of these small moons are debris generators,
可以使毫米直径的尘埃
creating the potential of millimeter-sized dust
在冥王星周围形成一个环
forming a ring around Pluto.
宇宙飞船通过冥王星系统时，飞得非常快
The spacecraft is flying so fast through the Pluto system,
时速大约3万英里
roughly 30,000 miles per hour,
因此即使是1毫米的微粒
that if it hit even a millimeter-sized particle,
都可能在船体上撞出一个洞
it could blow a hole in the spacecraft
使探测任务付诸东流
and it could destroy the mission.
1967年间
Back in 1967,
火星探测船“水手四号♥”
this almost happened to the
差点发生这样的意外
Mars probe Mariner 4.
水手四号♥飞进一片太空尘云
It ran into a cloud of space dust.
在45分钟时间中
And over the course of about 45 minutes,
船体上发生数以千计的撞击
they were seeing thousands of impacts on the spacecraft,
完全出乎意料
completely unexpected.
显然太空中有我们无法探测到的微粒
Clearly,there are particles out there that we can't detect
可能导致任务失败
that could potentially cause a loss of mission.
新视野号♥，可以承受多大的撞击?
How much of a beating can New Horizons take?
我们即将知道答案
We're about to find out