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Listen to part of a lecture in an astronomy class.
聽下面天文課程講座的一部分。
Now astronomy didn't really bloom into the science it is today until the development of spectroscopy.
現在天文學直到光譜學得以發展才真正發展成為今天的科學。
Spectroscopy is basically the study of spectra and spectral lines of light,
而光譜學基本上是研究光的光譜和光譜線,
and specifically for us,the light from stars.
以及專門我們而言,來自恒星的光。
It makes it possible to analyze the light emitted from stars.
它可以分析來自恒星發出的光。
When you analyze this light, you can figure out their distance from the earth, and identify what they are made of, determine their chemical composition.
當你分析這道光,你可以計算出它們和地球的距離,并確定其組成成分及化學成分。
Before we get into that though, it's probably a good thing to back up a bit.
但在我們深入之前，溫習一下上節課的內容可能也不錯。
You all know how when you take a crystal prism and pass a beam of sunlight through it, you get a spectrum,
你們都知道當你用一個水晶棱鏡并讓一束陽光穿過,你就得到一個譜,
which looks like a continuous band of rainbow colors.
它看上去就像一條彩虹般連續的顏色組合帶。
The light that we see with our human eyes as a band of rainbow color falls in a range of what's called visible light.
而我們通過人類的肉眼所看到的彩虹顏色組合光是被成為可見光的范圍。
And visible light spectroscopy is probably the most important kind of spectroscopy.
而可見光光譜可能是光譜學最重要的一類。
Anyone want to take a stab at the scientific term for visible light?
有沒有人想要嘗試用科學術語定義下可見光?
And I'm sure all of you know this because you all did the reading for today.
我肯定所有人都知道，這是因為你們每人都為今天做了溫習。
Optical radiation.
光學輻射。
But I thought being exposed to radiation is dangerous.
但我認為暴露于輻射中是危險的。
Yes, and no.
是的,沒有。
If you are talking about radiation, like in the element Uranium, yeah, that's dangerous.
如果你在談論輻射,比如鈾元素,是的,那是危險的。
But radiation as a general term actually refers to anything that spreads away from its source.
但是作為總體術語的輻射實際上指的是從其源頭發散出的任何物質。
So optical radiation is just visible light energy spreading out.
所以光學輻射只是可見光能量的傳播。
OK, so we've got a spectrum of a beam of sunlight and it looks like the colors bleed into each other.
好的,所以我們現在這束太陽光的光譜,看起來顏色已經互相融合。
There are no interruptions,
沒有間斷,
just a band flowing from violet to green, to yellow, to… you get the idea.
只是一種從紫色到綠色,黃色的色帶…你懂的。
Well, what happens if the sunlight's spectrum is magnified?
嗯,如果放大太陽光光譜會發生什么?
Maybe you all didn't do the reading.
也許你們所有人都沒有提前讀書。
Well, here's what you'd see.
嗯,這就是你會看到的。
I want you to know this that this spectrum is interrupted by dark lines called spectral lines.
我想讓你們注意到的是這一光譜是被叫做光譜線的暗線所打斷。
If you really magnify the spectrum of the sunlight, you could identify more than 100,000 of them.
如果你真的放大太陽光的光譜，你可以分辨出多達10萬條的光譜線，
They may look like kind of randomly placed,
它們或許看起來是隨機分布，
but they actually form many distinct patterns.
但實際上有很多不同的模式，
And if you were looking at the spectrum of some other star, the colors would be the same.
如果你看一些別的恒星的光譜，顏色會是一模一樣的，
But the spectral lines would break it up at different places, making different patterns.
但是這些光譜線會在不同的地方斷裂，形成不同的模式。
Each pattern stands for a distinct chemical element, and so different sets or patterns of spectral lines mean that the star has a different chemical composition.
每種模式代表著特別化學元素，而光譜線這樣不同的屬性和模式意味著這個恒星有著不同的化學組成。
So how do we know which spectral patterns match up with which elements?
我們如何了解哪個光譜模式對應于哪種元素？
Well, a kind of spectroscopic library of elements was compiled using flame tests.
一種光譜線庫通過火焰測試累積起來。
A known element, say a piece of iron for example, is heated in a pure gas flame.
比如鐵這種熟悉的元素在純凈的氣體火焰中加熱，
The iron eventually heats to the point that it radiates light.
最終鐵被加熱到一個點，輻射出光。
This light is passed through a prism, which breaks it up into a spectrum.
這道光通過棱鏡被打斷形成光譜。
And a unique pattern, kind of like a chemical fingerprint of spectral lines for that element appears.
而一種獨一無二的模式，類似于那種元素指紋的化學光譜顯現出來。
This process was repeated over and over again for many different elements,
對于許多不同的元素而言，這個過程一遍又一遍地重復，
so we can figure out the chemical makeup of another star by comparing the spectral pattern it has to the pattern of the elements in the library.
所以通過比較它的光譜模式與庫里元素的光譜模式，我們能夠弄清另一個恒星的化學組成，
Oh, an interesting story about how one of the elements was discovered through spectroscopy.
哦，這里有個有趣的故事是關于一個元素是如何通過光譜被發現的。
There was a pretty extensive library of spectral line patterns of elements even by the 1860s.
即使是在1860年，就已經存在一個強大的元素光譜模式庫了。
A British astronomer was analyzing a spectrograph of sunlight, and he noticed a particular pattern of spectral lines that didn't match anything in the library.
一位英國天文學家在分析太陽光的光譜時注意到一種特殊的光譜線模式與庫里的任何模式都不匹配。
So he put two and two together, and decided there was an element in the sun that hadn't been discovered here on the earth yet.
于是他兩兩組合對比，并確定有太陽上的一種元素在地球上還未被發現。
Any guesses about what that element is?
有人能猜出是哪種元素嗎？
It actually turned out to be pretty common and I'm sure all of you know it.
實際上它很普通，我肯定你們都認識。
OK. Let's try something else.
好的，我們換個角度來試試。
Any of you happened to be familiar with the Greek word for sun by chance?
你們有人碰巧知曉太陽在希臘語里的說法嗎？
Something like Helius or something like that.
可能是helius ，或者類似的。
Oh it must be Helium.
哦，肯定是Helium。
So you are saying that Helium was discovered on the sun first.
你是說氦是首先在太陽中被發現的。
Yes, and this is a good example of how important spectroscopy is in astronomy.
是的，這是光譜學在天文學中何等重要的一個顯著例子。
