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People have been awed by the sky ever since there were people, and today's astronomers are heirs to that millennia-long tradition.
从人类诞生以来，就对天空充满了敬畏之情。今天的天文学家就是千年后追随这脚步的后继人。
But what's surprising is that the way modern researchers study the sky hasn't really changed in the last few centuries.
但让人意外的是：过去几个世纪以来，现代天文学家研究天空的方式并没有实质性的改变。
Sure, our methods have gotten better, and there's the odd cosmic ray to keep things interesting.
没错，我们的方法确实有精进，这过程中也一直有奇异的宇宙射线出现，让研究更有趣。
But for the most part, astronomers still study things by analyzing their light, in other words, by looking at them.
但总体来看，天文学家依然通过光来探究事物。换言之，就是通过观测的方式来研究。
They look at stars. They look at galaxies. They look at empty space.
他们观测的对象有恒星、星系和无垠的宇宙。
They even look at dark matter, and you can't see dark matter!
他们甚至也观测暗物质，但问题是暗物质是看不到的啊！
Still, in the end, light is all astronomers need to consistently blow everyone's minds, and there are three main ways they use it.
不过，归根结底，所有天文学家还是需要通过光来进行持续的研究，主要是有3种方式：
The most obvious way is just taking pictures of things, whether in visible light or another wavelength like infrared.
最明显的方法就是拍照片：看看是可见光还是另一种波，比如红外线。
Essentially, light comes into a camera, and the camera spits out some kind of picture.
原理大概是：当光摄入摄像机的时候，摄像机会以图片的形式反馈出来。
This technique is a major way we study things like Saturn, Pluto's famous heart, and even distant planets.
这种技术是我们研究土星、冥王星著名的心形特征、甚至是其他遥远行星的主要方式。
But it's not just about collecting pretty pictures.
但并不只是收集好看的图像那样简单。
Results from direct imaging build off each other just like any other scientific method.
从直接成像获得的结果可以彼此互补，就像其他科学方法一样。
For example, besides helping us understand Pluto's heart, this method is also a big reason why we don't call Pluto a planet anymore.
比如，除了帮我们理解冥王星的心形特征之外，该方法也是我们不再将冥王星称为行星的一个重要原因。
That argument hinged on what else we directly saw in its orbit.
这一论断是直接依据是我们在其轨道上直接观测到的结果。
There is a lot you can't see just by looking straight at something, though, so astronomers have also had to develop other techniques.
有很多无法通过直接观测看到的事物，所以天文学家需要研究其他方法。
Their second trick is investigating polarization, or how light waves wiggle, or oscillate, as they travel through space.
他们的第二种方法就是研究偏振，也就是光波是如何在太空中震动的。
Generally, light from stars and most other sources starts out randomly polarized, oscillating in all different directions.
总体而言，恒星等物体发出的光一开始都是偏振的，会在各个方向震动。
But a few things can change that, like if a star is spinning really quickly, if light goes through certain kinds of gas clouds, or if a star has a magnetic field.
但有一些情况也能改变这一点，比如一颗恒星转速极快、光穿过某种气体云，或者某颗恒星自带磁场。
These are all things that would be hard or impossible to pick out through more direct imaging, so by measuring light's polarization, scientists can research things that would otherwise be invisible
这些通过直接成像是很难甚至无法获取的，所以通过测量光波的偏振，科学家就能研究本来不可见的物体。
They study polarization by stretching long, thin strips of molecules across something like a lens, making a filter that lets through some polarizations and not others.
他们研究偏振的方式是通过镜片将分子拉伸变得又长又瘦，经过这番过滤，就能留下偏振的情况。
Between these effects, astronomers have measured the magnetic fields of planets, the Sun, nebulas, interstellar dust, pulsars, galaxies, the list goes on and on.
通过这些效果，天文学家测量出了许多行星、太阳、星云、星际尘埃、脉冲星等的磁场。
And these numbers aren't just for funsies.
一点都没有夸张。
Since magnetic fields come from moving charged particles, those measurements tell us how matter and the charges in it are distributed throughout the universe.
鉴于我们都知道移动的带电粒子会产生磁场，所以这些测量可以告诉我们物质及其中的电荷是如何分布在宇宙中的。
Polarization measurements can also produce some of the most beautiful images in all of science,
偏振测量也可以获得科学界中最美妙的一些图像，
like this stunning visual of the Milky Way's magnetic field,
比如银河系磁场惊人的美丽图像，
where the colors tell you about its strength and the lines tell you about the polarization direction.
图像上的美丽色彩让我们知道其强度，而线条则可以让我们了解到偏振的方向。
Most astronomical journals aren't dominated by direct observations or polarization measurements, though.
不过，大多数天文学期刊上大多不是直接的观测或者偏振测量。
They're all about colors. Lots and lots of colors.
而是基本都与颜色有关，是很多的色彩。
There are a few types of astronomy like this, and they're all fundamentally based on studying the colors that enter a telescope instead of the full picture.
有一些天文学研究是这样的：基本是基于对色彩的研究，这些色彩是呈现在望远镜中而非全图的。
One method comes from black-body radiation.
有一种方法来自于黑体辐射。
The hotter something is, the more randomly its atoms move, and the more light they give off especially at higher energies.
一个物体的温度越高，其分子的移动就会越随意，他们发出的光就会越多，尤其是在能量更高的时候。
Measurements of something's black-body radiation spectrum, then, tell us about how hot it is.
通过测量某个物体的黑体辐射，就知道它的温度。
Stars' light usually peaks somewhere in visible light, whether that's red for the coolest stars or blue for the hottest.
恒星的光通常会在可见光的某处达到最亮，无论是温度最低的恒星所散发出的红色，还是温度最高的恒星所散发出的蓝色。
But things like the accretion disks around black holes, where gas is falling in, are hotter than the hottest stars, and we know that because they emit lots of x-rays.
但有一些物体，比如黑洞附近的吸积盘，气体会流入，这里的温度要比温度最高的恒星还要高。我们之所以知道这一点是因为它们会释放出大量的X光射线。
Empty space, on the other hand, is much colder.
而空旷的空间里温度相对低很多。
And, again, we know because of its black-body spectrum, called the Cosmic Microwave Background.
我们知道这一点依然是因为其黑体辐射，也叫宇宙微波背景。
So just using light, we're able to get a pretty good idea of the temperature of things, no thermometer required.
所以，只需要通过光，我们就能充分了解物体的温度，根本不需要温度计。
A second way astronomers use color is through spectroscopy.
天文学家使用色彩的第二种途径是通过光谱学。
Every atom and molecule absorbs and emits light from some colors much better than others.
每个原子和分子吸收和释放某些颜色的光，要比吸收其他颜色光更容易。
And after years of study, scientists have figured out how many of those particles behave.
经过多年的研究，科学家弄清楚了分子的作用机制。
They can even graph their light patterns on a chart, kind of like a fingerprint.
他们甚至能在表格上绘制光带的光带，有点像手印。
So when they get new data from stars or interstellar dust or extrasolar planets, they can figure out what the objects are made of just by matching up sets of lines.
所以，他们从恒星、星际尘埃、系外行星那里获得新数据之后，就能通过给线组配对来了解物体的组成。
Well, almost. Often, when we're studying really distant objects, their spectral lines aren't the right colors.
基本上是这样。通常情况下，当我们研究遥远的物体时，它们的光谱线颜色都不太正常。
They're usually redder than we'd guess or sometimes they're bluer.
通常都要比我们猜想的更红或者更蓝。
And that's because of Doppler shifts, another one of the most fundamental tools in observational astronomy.
这是因为多普勒频移，这是观测天文学中另一种最为常见的工具。
Light gets stretched or compressed by movement, and the amount it's distorted tells you how fast it's moving toward or away from you.
光会因为移动而得到拉伸或者压缩，而其频移的程度可以告诉我们它运动的速度，无论是朝我们运动还是离我们远去。
Doppler shifts were used by Edwin Hubble to discover the universe is expanding,
爱德文·哈勃通过多普勒频移发现了宇宙在膨胀的事实。
they've been used in all sorts of ways to infer the existence of dark matter,
多普勒频移还用在了其他方面来推断暗物质的存在。
they've revealed hundreds of exoplanets, and they've been used for everything in between.
还揭示出了上百颗系外行星的存在，可以说，多普勒频移无处不在。
The fact that we've been able to do so much with light is pretty mind-blowing.
我们居然能用光做这么多事情，真是让人吃惊。
And it also helps explain why, as astronomers discover different ways of exploring the universe, like gravitational waves and neutrinos, they've been so excited.
也能助力解释为什么天文学家发现探索宇宙（比如引力波和中微子）不同方法的时候，会如此兴奋。
We've been using nothing but light for hundreds and hundreds of years.
近数万年来，我们一直在利用光来探索宇宙。
Imagine what we're going to be able to do learn with something new.
接下来我们会通过光来研究什么呢。
If you want to learn even more about those gravitational waves and what new things we might be able to learn from them, you can watch our episode about it.
如果大家想了解更多与引力波有关的知识或者其他新知识的话，可以观看我们相关的视频。
And as always, thanks for watching this episode of SciShow Space!
再次感谢所有粉丝对本节目的支持！
