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Hello, and welcome to Crash Course Astronomy!
大家好，欢迎来到天文学速成班课堂！
I'm your host, Phil Plait, and I'll be taking you on a guided tour of the entire Universe.
我是主持人，菲尔·普莱特，我将带你游览整个宇宙。
You might want to pack a lunch.
你可能要带上午餐哦。
Over the course of this series we'll explore planets, stars, black holes, galaxies, subatomic particles, and even the eventual fate of the Universe itself.
在本系列的课程中，我们将探索行星、恒星、黑洞、星系、亚原子粒子，甚至宇宙本身的最终命运。
But before we step into space, let's take a step back.
但在我们进入太空之前，让我们先退一步。
I wanna talk to you about science.
我想先和你谈谈科学。
There are lots of definitions of science, but I'll say that it's a body of knowledge, and a method of how we learned that knowledge.
科学有很多定义，但我想说它是一个知识体系，是我们学习知识的一种方法。
Science tells us that stuff we think we know may not be perfectly known; it may be partly or entirely wrong.
科学告诉我们，我们所知道的东西可能并没有得到完全的认知；我们所知晓的只是一个部分，或完全就是错误的。
We need to watch the Universe, see how it behaves, make guesses about why it's doing what it's doing, and then try to think of ways to support or disprove those ideas.
我们需要观察宇宙，观察它是如何运转的，猜测它为什么这样做，然后试图找到支持或反驳这些观点的方法。
That last part is important.
最后一点很重要。
Science must be, above all else — honest, if we really want to get to the bottom of things.
如果我们真想弄清事情的真相，科学首先必须是诚实的。
Understanding that our understanding might be wrong is essential, and trying to figure out the ways we may be mistaken is the only way that science can help us find our way to the truth, or at least the nearest approximation to it.
认识到我们的认识可能是错误的这一点至关重要，而试图找出我们可能出的错是科学帮助我们找到通往真理的道路的唯一途径，或者至少是最接近真理的道路。
Science learns.
科学会自我纠正。
We meander a bit as we use it, but in the long run, we get closer and closer to understanding reality, and that is the strength of science.
每次运用它是我们都会蜿蜒前进一小步，长此以往，我们就会越来越接近真理，这就是科学的力量。
And it's all around us!
而它无处不在！
Whether you know it or not, you're soaking in science.
不管你是否意识到，你都沉浸在科学中。
You're a primate.
你是一个灵长类动物。
You have mass.
你有质量。
Mitochondria in your cells are generating energy.
你细胞中的线粒体正在产生能量。
Presumably, you're breathing oxygen.
相比你也正在呼吸着氧气。
But astronomy is different.
但天文学不同。
It's still science, of course, but astronomy puts you in your place.
当然，它仍然是科学，但天文学能让你找到自己所处的位置。
Because of astronomy, I know we're standing on a sphere of mostly molten rock and metal 13,000 kilometers across, with a fuzzy atmosphere about 100 km high.
因为天文学的缘故，我知道我们正站这样一个球体表面，它主要由熔化的岩石和金属组成，直径有13,000千米，被100千米厚的大气层环绕。
Surrounded by a magnetic field that protects us from the onslaught of subatomic particles from the Sun 150 million km away.
球体周围的磁场保护我们免受来自1.5亿公里外太阳的亚原子粒子的冲击。
Which is also flooding space with light that reaches across space, to illuminate the planets, asteroids, dust, and comets, racing out past the Kuiper Belt, through the Oort Cloud, into interstellar space, past the nearest stars, which orbit along with gas clouds and dust lanes in a gigantic spiral galaxy we call the Milky Way that has a supermassive black hole in its center.
这些粒子与光一起冲向宇宙，照亮了行星、小行星、星尘、彗星，冲过柯伊伯带、穿过奥尔特星云、进入星际空间、经过最近的恒星，而这些恒星正随着气体云和星尘绕着螺旋状的银河转动，银河系的中心还有一个黑洞。
And is surrounded by 150 globular clusters and a halo of dark matter and dwarf galaxies, some of which it's eating, all of which can be seen by other galaxies in our Local Group like Andromeda and Triangulum.
有150个球状星团、一个暗物质晕和一些矮星系正绕着这个黑洞转，而这些矮星系中的一部分正在被黑洞吞噬，这都可以在我们的本星系群中被观察到，比如仙女座和三角座星系。
And our group is on the outskirts of the Virgo galaxy cluster, which is part of the Virgo supercluster, which is just one of many other gigantic structures that stretch most of the way across the visible Universe, which is 90-billion light years across and expanding every day, even faster today than yesterday due to mysterious dark energy, and even all that might be part of an infinitely larger multiverse that extends forever both in time and space.
而我们的本星系群处于处女座星系团，而处女座星系团又处于处女座超星系团，超星系团又仅是无数铺展在可见宇宙中的巨型结构中的一个，我们的可见宇宙直径900亿光年，并每天都在暗能量的作用下加速膨胀，而所有的这一切又有可能只是无限大的在时间和空间中无限膨胀的多重宇宙中的一部分。
See?
看到了吧？
Astronomy puts you in your place.
天文学让你知道了你所处的位置。
But what exactly is astronomy?
但天文学到底是什么？
This isn't necessarily an obvious thing to ask.
这并不是一个简单的问题。
When I was a kid, it was easy: Astronomy is the study of things in the sky.
当我还是个孩子的时候，觉得这很简单：天文学是研究天空中事物的科学。
The sun, moon, stars, galaxies, and stuff like that.
比如太阳、月亮、恒星、星系等等。
But it's not so easy to pigeonhole these days.
不过现在却没那么容易区分开来。
Take, for example, Mars.
拿火星举个例子吧。
When I haul my scope out to the end of my driveway and look at Mars, that's astronomy, right?
当我拿着望远镜在家门口观察它时，这就是天文学了，对吧？
Of course!
没错！
But what about the rovers there?
不过那些探测器又如何？
Those machines aren't doing astronomy, surely.
它们显然不在从事天文学研究。
They're doing chemistry, geology, hydrology, petrology. . . everything but astronomy!
它们研究化学、地理、水文、岩石等等，总之都不是天文学！
So nowadays, what's astronomy?
那么现在，什么是天文学呢？
I'd say it's still studying stuff in the sky, but it's branched out quite a bit from there.
我会说它仍然是研究太空中物体的学科，但它也拓展了很多。
Borders between it and other fields of science are fuzzy. . . a theme I'll be hitting on several times over this series.
与其他学科的边界很模糊……在这个系列中我会多次触及这一点。
Humans might like firm, delineated boundaries between things, but nature isn't so picky.
人类可能喜欢在事物之间划定坚实的界限，但大自然并没有那么讲究。
And that brings us to our first edition of "Focus On. . ."
这就把我们带到第一个“焦点问题”……
This week's topic: Astronomers!
本周主题：天文学家！
Who are we?
天文学家都是谁？
What do we do?
做些什么？
I used to look through telescopes for a living, or at least study the data that came from detectors strapped onto them.
我本来以从太空望远镜中观察天体为生，或者至少也是研究它们携带的探测器所产生的数据。
But now I talk and write (and make videos) about astronomy, and relegate my viewing to my personal backyard telescope.
不过现在我做关于天文学的演讲、写作（以及视频制作），我仅仅使用我家后院的望远镜进行天文学观测了。
But I still consider myself an astronomer, so that should give you an idea that there's a lot of wiggle room in the profession.
不过我仍然认为我是一个天文学家，这应该可以给你们一些关于本专业回旋余地的概念了。
In fact, when I worked on Hubble Space Telescope, I was actually hired as. . . a programmer!
事实上，当我在哈勃太空望远镜工作的时候，我被雇佣的身份是……程序员！
I coded in the language used by the folks helping to build and calibrate a camera that was due to launch into space and be installed onto Hubble by an astronaut.
我编程所用的语言被用来帮助建立和校准一个相机，这个相机会被送入太空，由宇航员安装到哈勃望远镜上。
Once the data from that camera are taken and analyzed, you have to know what to do with them.
当我们从相机上获得数据后，你必须知道该如何处理它们。
Do the observations fit the physical model of how stars blow up, or how galaxies form, or the way gas flows through space?
这些观测结果是否符合恒星爆炸过程的物理模型？星系如何形成？气体如何在太空中流动？
Well, you better know your math and physics, because that's how we test our hypotheses.
你最好擅长数学和物理，因为那是我们检验假设的方式。
And someone who does that is generally called an astrophysicist.
做这些工作的人通常被称为天体物理学家。
Of course, those telescopes and detectors don't create themselves.
当然，这些望远镜和探测器不会自己产生。
We need engineers to design and build them and technicians to use them.
需要有工程师来设计和制造它们，还需要有技术人员来使用它们。
Most astronomers don't actually use the telescopes themselves anymore; someone who's trained in their specific use does that for them.
大多数天文学家实际上已经不再亲自使用望远镜了；另一些经过专业训练的人会为他们做这些。
Some of those instruments go into space, and some go to other worlds, like the moon and Mars.
这些仪器有的会进入太空，另一些会飞向其他星球，如月球和火星。
We need astronomers and engineers and software programmers who can build those, too.
我们也需要天文学家、工程师和软件程序员。
And then, at the end of all this, we need people to tell you all about it.
最后，我们还需要可以告诉大家这些的人。
Teachers, professors, writers, video makers, even artists.
老师、教授、作家、视频制作人，甚至艺术家。
So I'll tell you what: If you have an interest in the Universe, if you love to look up at the stars, if you crave to understand what's going on literally over your head, then who am I to say you're not an astronomer?
所以我要告诉你：如果你对宇宙感兴趣，如果你喜欢仰望星空，如果你渴望了解你头顶上发生的一切，谁又能说你不是个天文学家呢？
However you define astronomy, humans have been looking up at the sky for as long as we've been humans.
不管你如何定义天文学，人类从诞生之初就开始仰望星空。
Certainly ancient people noticed the big glowy ball in the sky, and how it lit everything up while it was up, and how it got dark when it was gone.
古人们注意到天空中那个发光的球体，注意到它如何在白天照亮一切，如何在夜晚变暗。
The other, fainter glowy thing tried, but wasn't quite as good as lighting up the night.
另一个发光的球体也试图照亮天空，不过效果就没那么好。
They probably took that sort of thing pretty seriously.
他们大概对那样的事特别重视。
They probably also noticed that when certain stars appeared in the sky, the weather started getting warmer and the days longer, and when other stars were seen, the weather would get colder and daytime shorten.
他们可能还注意到，当天空中出现某些星星时，天气会开始变暖，白天开始变长，而当看到其他星星时，天气就开始变冷，白天变短。
And when humans settled down, discovered agriculture, and started farming, noticing those patterns in the sky would have had an even greater impact.
当人类定居下来，发现农作物，并开始耕种时，关注这些天象有更重要的意义。
It told them when to plant seeds, and when to harvest.
这告诉他们何时播种、何时收获。
The cycles in the sky became pretty important.
天空中的轨道变得非常重要。
So important that it wasn't hard to imagine gods up there, looking down on us weak and ridiculous humans, interfering with our lives.
以至于不难想象有神的存在，他们俯视着脆弱滑稽的人类、干扰我们的生活。
Surely if the stars tell us when to plant, and control the weather, seasons, and the length of the day, they control our lives too. . . and astrology was born.
显然，如果星星告诉我们什么时候播种，控制天气、季节和一天的长短，那它们也就控制着我们的生活……于是占星术就诞生了。
Astrology literally means "study of the stars"; as a word it's been used before science became a formal method of studying nature.
占星术的字面意思是“关于星星的研究”；这个词在科学成为研究自然的正式方法之前就已经被使用很久了。
It irks me a bit, since it got the good name, and now we're stuck with "astronomy," which means "law or culture of the stars."
这让我不太高兴，占星术占了个好名字，而我们只能使用天文学（astronomy）这个词，意思是星星的规律。
That's not really what we do!
但这并不完全是我们所研究的内容。
But what the heck.
不过管他呢。
Words change meaning over time, and now it's pretty well understood that astronomy is science, and astrology. . . isn't.
词汇的意思经常改变，如今人们普遍理解天文学是科学，而占星术……不是。
Millennia ago, astrology was as close to science as you got.
几千年前，占星术士是最接近科学的了。
It had some of the flavors of science: astrologers observed the skies, made predictions about how it would affect people, and then those people would provide evidence for it by swearing up and down it worked.
它有一些科学的元素：占星术士观察天空，并预测它将如何影响人类，然后这些人会通过诅咒发誓它一定应验来提供证据。
The thing is, it really didn't; the fault of astrology lies in ourselves and not our stars.
但是它并不灵验；占星术的问题在于我们自己的偏见而不是星星。
People tend to remember the hits and forget the misses when predictions are made, which is why they sometimes sit in casinos pumping nickels into machines that are in proven to be nothing more than a method for reducing the number of nickels you have.
因为人们总是倾向于记住得到印证的语言而忘记那些没有实现的，这大概是问什么即使明知老*机虎**唯一的用处就是减少你金钱的数量，也总有些人会坐在*场赌**里不断给它们喂硬币的原因。
But astrology led to people to really study the sky, and find the patterns there, which led to a more rigorous understanding of how things worked in the heavenly vault.
但占星术引导人们真正地去研究天空，寻找星星排布的模式，最终形成了对苍穹中物体如何运行更严格的认识。
It wasn't overnight, of course.
这当然不是一蹴而就的。
This took centuries.
而是经过了几个世纪。
Before the invention of the telescope, keen observers built all sorts of odd and wonderful devices to measure the heavens, and in fact it was before the telescope was first turned to the sky that a huge revolution in astronomy took place.
在望远镜被发明之前，敏锐的观测者们建造了各种奇妙的仪器来丈量天空，事实上，天文学中的一次重大革命在天文望远镜被发明之前就发生了。
It is patently obvious that the ground you stand on is fixed, rooted if you will, and the skies turn above us.
很明显，我们立足的大地是固定不动的，而天空绕着我们旋转。
The sun rises, the sun sets.
太阳升起落下。
The moon rises and sets, the stars themselves wheel around the sky at night.
月亮也升起落下，星星也在夜空中旋转。
Clearly, the Earth is motionless, and the sky is what is actually moving.
显而易见，地球不动而天空在旋转。
In fact, if you think about it, geocentrism makes perfect sense that all the objects in the sky revolve about the Earth, and are fixed to a series of nested spheres, some of which are transparent, maybe made of crystal, which spin once per day.
实际上，如果你仔细想想，地心说是很有道理的，天空中所有的物体都绕着地球旋转，并固定在一系列嵌套的球体上，其中一些是透明的，可能是水晶做的，每天自转一次。
The stars may just be holes in the otherwise opaque sphere, letting sunlight though.
而星星也许就是一些原本不透明的天球上的孔洞，使得阳光可以穿透。
Sounds silly to you, doesn't it?
听着有点傻，不是么？
Well, here's the thing: If you don't have today's modern understanding of how the cosmos works, this whole multiple-shells-of-things-in-the-sky thing actually does make sense.
不过话说回来：如果你没有现代宇宙学知识，那么这个多层嵌套天球体系其实挺有道理的。
It explains a lot of what's going on over your head, and if it was good enough for Plato, Aristotle, and Ptolemy, then by god it was good enough for you.
它能解释我们头顶上空发生的现象，并且如果这个理论对柏拉图、亚里士多德和托勒密这样的人来说都足够好了，那估计对你来说也够好。
And speaking of which, it was endorsed by the major religions of the time, so maybe it's better if you just nod and agree and don't think about it too hard.
说起来这个理论还得到了当时主流宗教的支持，所以你最好也就点头接受，就别想太多了。
But a few centuries ago, things changed.
但几个世纪前，情况发生了变化。
Although he wasn't the first, the Polish mathematician and astronomer Copernicus came up with the idea that the sun was the center of the solar system, not the Earth.
虽然并不是第一个，但波兰数学家和天文学家哥白尼提出了太阳才是星系的中心而非地球的观点。
His ideas had problems, which we'll get to in a later episode, but it did an incrementally better job than geocentrism.
他的想法其实有些问题，我们将在以后的课程中讨论，不过已经比地心说进步很多了。
And then along came Tycho Brahe and Johannes Kepler, who modified that system, making it even better.
之后，布拉赫可开普勒修改了日心说体系，使之更完善。
Then Isaac Newton — oh, Newton — he invented calculus, partly to help him understand the way objects moved in space.
在之后，艾萨克·牛顿发明了微积分，部分被用于解释天体的运动。
Over time, our math got better, our physics got better, and our understanding grew.
随着时间的推移，我们的数学和物理越来越先进，我们的理解力也越来越强。
Applied math was a revolution in astronomy, and then the use of telescopes was another.
应用数学是天文学的一场革命，其次是望远镜的使用。
Galileo didn't invent the telescope, by the way, but made them better; Newton invented a new kind that was even better than that, and we've run with the idea from there.
顺便说一句，伽利略并没有发明望远镜，而只是改进了它；之后牛顿发明了一种更好的新望远镜，沿用至今。
Then, about a century or so ago, came another revolution: photography.
然后在大约一个世纪前，又有了另一场革命：摄影术。
We could capture much fainter objects on glass plates sprayed with light-sensitive chemicals, which revealed stars otherwise invisible to us, details in galaxies, beautiful clouds of gas and dust in space.
我们可以在喷洒了光敏化学物质的玻璃板上捕捉到更暗淡的天体影像，而这些本来是肉眼不可见的星星、星系的细节、太空中美丽的气体和尘埃星云。
And then in the latter half of the last century, digital detectors were invented, which were even more sensitive than film.
然后在上个世纪的后半叶，数字探测器被发明了出来，它甚至比胶片还灵敏。
We could use computers to directly analyze observations, and our knowledge leaped again.
我们可以用计算机直接分析观测结果，这使得我们的知识又一次产生飞跃。
When these were coupled with telescopes sent in orbit around the Earth — where our roiling and boiling atmosphere doesn't blur out observations — we began yet another revolution.
当它们与环绕地球的轨道上的望远镜结合在一起时——那里没有翻滚变动的大气层来模糊我们的视线——又一次革命开始了。
And where are we now?
所以我们现在在何处呢？
We've come such a long way!
我们已经走了很长一段路了！
What questions can we routinely ask that our ancestors would not have dared?
有些什么问题是我们现在常常会问起，而我们的祖先却不敢问的？
What statements made with a pretty good degree of certainty?
我们可以带着相当程度的确定性作出什么样的声明？
Think on this: The lights in the sky are stars!
想想这个：天空中的亮光来自恒星。
There are other worlds.
还有其他的世界存在。
We take the idea of looking for life on alien planets seriously, and spend billions of dollars doing it.
我们十分认真地寻找外星生命，并为此花费数十亿美元。
Our galaxy is one of a hundred billion others.
我们的星系只是千亿个星系中的一个。
We can only directly see 4% of the Universe.
我们只能直接看到4%的宇宙。
Stars explode, and when they do they create the stuff of life: the iron in our blood, the calcium in our bones, the phosphorus that is the backbone of our DNA.
恒星会爆炸，并在这个过程中创造出生命的基本元素：我们血液中的铁、骨骼中的钙、DNA的骨架中的磷。
The most common kind of star in the Universe is so faint you can't see it without a telescope.
宇宙中最常见的一种恒星非常暗淡，以至于不借助望远镜就无法观测。
Our solar system is filled to overflowing with worlds more bizarre than we could have dreamed.
我们的太阳系中充斥着只会在梦中见到的古怪世界。
Nature has more imagination than we do.
大自然远比人类更有想象力。
It comes up with some nutty stuff.
创造出各种疯狂的东西。
We're clever too, we big-brained apes.
我们这些大脑瓜的猿猴们也很聪明。
We've learned a lot. . . but there's still a long way to go.
我们已经学到了很多……但仍然前路漫漫。
So, with that, I think we're ready.
至此，我想我们已经准备好了。
Let's explore the universe.
让我们开始探索宇宙吧。
Today you learned what astronomy is, and that astronomers aren't just people who operate telescopes, but include mathematicians, engineers, technicians, programmers, and even artists.
今天你学习了什么是天文学，天文学家不仅仅是操作望远镜的人，还包括数学家、工程师、技术人员、程序员，甚至艺术家。
We also wrapped up with a quick history of the origins and development of astronomy, from ancient observers to the Hubble Space Telescope.
我们还总结了天文学的起源和发展的简史，从古代的观察者到哈勃太空望远镜。
Crash Course is produced in association with PBS Digital Studios.
Crash Course 是与 PBS 数字工作室联合制作的。
This episode was written by me, Phil Plait.
我是菲尔·普莱特，这一集是由我创作的。
The script was edited by Blake de Pastino, and our consultant is Dr. Michelle Thaller.
脚本由 Blake de Pastino 编辑，我们的顾问是 Michelle Thaller 博士。
It was co-directed by Nicholas Jenkins and Michael Aranda, and the graphics team is Thought Café.
本片由尼古拉斯·詹金斯(Nicholas Jenkins)和迈克尔·阿兰达(Michael Aranda)联合执导，视频画面团队是 Thought Cafe。