宇宙（2007）

Vasimr's ion engine gets an added
等离子体火箭的离子引擎增添了
radio frequency generator and a second stage.
射频发生器和二级推进器
One of the key things is it works kind of like a microwave oven.
很重要的一点是它的工作原理有点像微波炉
Just like a microwave beams electromagnetic energy
微波炉发出电磁波
into the food to superheat it.
来加热食物
As the plasma gets superheated,
等离子体被加热后
then it's got way more energy,
它获得了多得多的能量
It's got this really strong magnetic field that takes
加热过的等离子体贮存在
that superheated plasma
探测器的很强的磁场中
And shoots it out the back end at really high velocities.
并以极快的速度从其尾部喷射出来
The ions can be superheated to about one million degrees.
离子能够被加热到大约一百万度
That's enough to send a probe far beyond our solar system.
那足以将一个探测器送到我们太阳系之外很远
As rocket technology advances,
随着火箭技术的发展
the gates of deep space are swinging open to exploration.
深空探索的大门正在打开
All we need is a destination.
我们需要的只是目的地
One space probe is right now
一个空间探测器此刻
scanning the heavens for that destination:
正在宇宙中仔细寻找那个目的地
a new earth, and possibly a new form of life.
一个新的地球 很有可能一种新的生命形式
Space probes are on the cutting edge of one of astronomy's oldest quests:
空间探测器正站在天文学最古老追求之一的最前沿
the search for another earth.
寻找另一个地球
Now, a new generation of robotic explorers
现在 新一代的机器人探测器
seeks evidence of extrasolar planets.
找到了太阳系外行星的证据
And we're finding them.
我们正在寻找它们
An extrasolar planet is simply
太阳系外行星简单来说
a planet that orbits another star.
就是一颗绕另一颗恒星运转的行星
We have eight major planets orbiting our sun,
我们太阳系有八大行星
and our sun is a typical star.
而太阳是一颗典型的恒星
And so a question that has loomed for centuries is
几个世纪以来一直存在的一个问题是
whether there are planets that orbit the stars that we see at night.
是否有行星围绕我们在夜空中看到的星星运转
Since the days of Galileo,
自伽利略时代♥开♥始
scientists have believed there must be other planets
科学家们就相信在天空中的亿万颗星中
among the billions of stars in the sky.
一定存在其他行星
But the quest for extrasolar or exoplanets
但对太阳系外行星的探寻
wasn't successful until 400 years after Galileo.
直到伽利略之后四百年才得以成功
In 1995, in the Pegasus constellation,
一九九五年 在仅仅离地球五十光年的
just 50 light-years from earth,
飞马星座
Scientists discovered the first true
科学家们发现了第一颗真正的
extrasolar planet, 51 Pegasi b.
太阳系外行星 飞马座51b
It was found only through indirect clues.
它仅仅是通过间接的线索发现的
We were only being able to find these extrasolar planets
我们只有通过一种"恒星摇摆法"
using a technique called star wobble.
才能找到这些太阳系外行星
If you have a big planet like a Jupiter out there,
如果有一颗像木星一样的大行星存在
it would cause the star's motion to wobble.
它会引起恒星的运动出现摇摆
But you couldn't really sort of directly tell it was there.
但你不能直接说它就在那里
Also called the Doppler effect,
也称为多普勒效应
The wobble is observed through a telescope.
摇摆是通过望远镜发现的
If the star's light regularly shifts
如果恒星的光波有规律地
toward red or blue wavelengths and then back again,
反复发生红移和蓝移
Then an orbiting planet must be causing the light to shift.
那么围绕其运行的行星一定是引起光波偏移的原因
In the last decade or so, astronomers have been extremely lucky
在过去的十多年 天文学家很幸运地
to find hundreds of planets around other stars.
发现了围绕其他恒星运行的上百颗行星
But the planets we've been finding are the large ones:
但我们发现的行星是巨行星
the Jupiters, the Saturns, some Neptunes.
像木星 土星和海王星那种
We have not been able to find the earth-like planets,
我们还不能够发现类似地球大小的行星
if they're out there.
如果它们存在的话
There are now hundreds of verified extrasolar planets.
人类已经发现了数百颗太阳系外行星
But are any of these planets close enough for mankind to explore?
但它们中存在离地球足够近可以供人类探索的吗
That's what Annabelle C. From Erie, Pennsylvania,
来自宾夕法尼亚州伊利的安娜贝尔·C
wanted to "Ask the universe," when she texted us...
向《宇宙解密》这样问道
How long would it take for a space probe reach the nearest explanet?
利用当今最先进的推进系统
Using theest propulsion available today?
空间探测器要花多久才能到达最近的系外行星
Annabelle, that's a really interesting question,
安娜贝尔 很有意思的问题
And, in fact, there's no set answer.
而事实上 没有既定的答案
Using today's technology,
使用今天的技术
A space probe could reach another star in about 100,000 years.
空间探测器花大约十万年才能到达另一颗恒星
The nearest known exoplanet is about 10 1/2 light-years away,
已知最近的太阳系外行星距地球10.5光年
But there might be a more nearby one,
但有可能存在离地球更近的
or we might improve space propulsion technology in the near future.
或者我们可以在不久的将来改进推进技术
So maybe we could get that down to about 10,000 years
所以在相对不久的将来 也许我们能够
in the relatively near future,
把时间缩短到大约一万年
But something like 50,000 to 200,000 years
但对于现在来说 五万到二十万年
is a good answer for right now.
是一个比较好的答案
Finding the earth-like planets means looking deeper into the cosmos,
寻找类地行星意味着到宇宙更深处探索
at dimmer and more distant stars.
去寻找更模糊和更遥远的恒星
A revolutionary method of watching these dim stars
一种革命性的观察遥远恒星的技术
could soon pinpoint the first new earth.
有可能会很快找出第一颗类地行星
It's called the transit technique,
这种技术被称为凌日法
and it offers a dead giveaway that an orbiting planet
这种技术在行星绕过
is crossing between the star and our viewpoint from earth.
我们视角下的恒星盘面时发现行星
So, let's imagine this reflector is like the face of a star
我们假设这个反射镜是恒星的盘面
and a bug flying in front of that reflector is like the planet.
而在反射镜前面飞行的昆虫就像那颗行星
As the bug goes in front of and around this reflector,
随着虫子围绕着反射镜前飞过时
it will block a little bit of the light from the reflector,
它会挡住反射镜一部分的光
just as would happen when a planet crosses
就同一颗行星运转时经过
in front of a sun-like star.
恒星前面时发生的情况一样
The amount of dimming
光的减弱程度
is often less than 1/10 of 1% of the star's light output.
往往小于恒星发出光强度的千分之一
Barely noticeable, but it's more than enough
很难注意到 但对于一个在宇宙中探索的
for one far-sighted space probe that's now scouting the cosmos.
拥有千里眼的空间探测器来说已经很足够了
We'd love to know if there's another earth-like planet
我们很想知道宇宙中是否存在一颗
out there somewhere, and the Kepler mission
类似地球的行星 如果有的话
has a good chance of being able to see it if there is one.
开普勒计划大有可能找到它
The Kepler space probe is the powerful eye
卡普勒号♥宇宙探测器是
scientists will use to find the earth-like planets,
科学家们用以发现类地行星的强有力工具
the proverbial needles in the haystack.
如谚语说的大海捞针
The probe's telescope is using a 95-megapixel camera
探测器的望远镜使用九千五百万像素的摄像机
to watch for the transiting planets.
来观察经过的行星
The Kepler mission is using the so-called transit technique
开普勒计划用所谓的"凌日法"
to search for new extrasolar planets.
来寻找新的太阳系外行星
With the transit technique,
使用凌日法
Kepler is watching thousands of stars,
开普勒号♥探测器能够观察成千上万的恒星
Waiting for their light to slightly dim
捕捉它们在行星经过时
When a planet passes in front of the star.
亮度的轻微减弱
The milky way is composed of billions of stars,
银河系中有几十亿颗恒星
And potentially, billions of earth-like planets.
也可能有几十亿颗类地行星
The odds of finding one earth
能都找到一颗类地行星
orbiting one particular star are very low.
围绕某颗恒星运转的几率很低
So, Kepler will train its unblinking eye
所以 开普勒会同时日夜不停地
on many thousands of stars at the same time.
观测数千颗恒星
Here I have a DVD to represent a planetary system
我这有张光盘用来代表一个行星系
with the star in the center and a planet going around the outside,
其恒星在中间 一颗行星在外♥围♥绕它运转
And of course, most of the time,
当然 大部分时间
the planetary system is tilted to our line of sight.
该行星系同我们的视线平行
And so, as the planet goes around,
所以随着行星的运转
it never crosses in front of the star, blocking the starlight.
它永远不会经过恒星前面 挡住星光
But if we're lucky,
但如果我们幸运的话
and the orbital plane of the planet is seen edge on,
能够看到行星的轨道面
then the planet crosses in front of the star,
当行星运转经过恒星前面时
blocking some of the starlight, and dimming the star.
挡住了部分光线 使恒星变得暗淡
And so, you have to be watching
所以 你得观察数万
tens or even hundreds of thousands of stars
甚至数十万的恒星
to be lucky enough to catch a few planets
才能有幸捕捉到一些行星
that happen to cross right in front of the star.
刚好运行在恒星前面
As the world waits, kepler watches
全世界在等待的同时 开普勒号♥探测器
the distant stars moment by moment.
每时每刻都在关注着遥远的恒星
But if it does find a new earth,
但如果它真的找到一颗新的地球
What can we actually find out about it?
我们能够真正意义上地发现什么呢
What will it look like?
它看上去会像什么
Could there be life?
那里会有生命吗
Once Kepler finds earth-like planets,
一旦开普勒发现像地球一样的行星