
Today that sounds ridiculous.
今日這種說法聽來荒唐
But two hundred years ago it didn't seem so unlikely.
但是兩百年前還頗言之成理
It was widely believed that
當(dāng)時一般人認為
the Earth was only a few thousand years old.
地球只有幾千年的歷史
But in the mid-nineteenth century a new science
但是19世紀中期
was emerging that was painting
一股新的科學(xué)勢力興起
a very different picture of the age of the Earth.
并對地球的年齡提出截然不同的見解
By looking at the deepest layers of rocks geologists
地質(zhì)學(xué)家研究深層巖石后
were discovering that the Earth was much older
發(fā)現(xiàn)地球年齡遠超出
than anyone had previously imagined.
一般人的預(yù)期
If that was true then the sun also had to
如果此言屬實
have been burning for much,much longer.
那么太陽燃燒的時間也應(yīng)該久得多
You can see the strata and the lines in the rock in back of you
后方巖石的地層和線條
that represent hundreds of
代表了
millions of years of geological history.
好幾億年的地質(zhì)歷史
The top of Sacramento Peak up beyond this,
我們在更后面的沙加緬度峰上
we find fossils that are 300 million years old.
找到了有三億年歷史的化石
Below Sacramento Peak you've got more than a kilometre
沙加緬度峰下方,有一公里多的地層
of these strata that are far older than that.
年代比三億年還久遠
From the age of these strata geologists knew
地質(zhì)學(xué)家藉由這些地層得知
that the earth was at least a billion years old.
地球的歷史至少有十億年
At the same time astronomers thought
但天文學(xué)家卻認為
the sun was only 10, 000 years old.
太陽只有一萬年的歷史
If the geologists were right then astronomers
如果地質(zhì)學(xué)家說得對,那么天文學(xué)家
had to find some other source for the Sun producing its energy.
必須另外想辦法解釋太陽能量的來源
The search for the source of energy
尋找支持了太陽
that could power the sun for billions of years
數(shù)十億年的能量來源
lasted for nearly a century.
持續(xù)了將近一個世紀
Eventually scientists would find the answer in the forces
最后科學(xué)家終于在凝聚原子的力量
that hold atoms together and in the nature of matter itself.
和物質(zhì)的本質(zhì)中找到答案
But first you have to know what the sun is made of.
但首先我們必須先搞清楚太陽的組成
To find that out you need to take a very close look at sunlight.
想要得到答案,必須仔細觀察陽光
When you take the light from the Sun and pass it through a prism,
若讓陽光穿過棱鏡
spread it out into the colours,
讓陽光分色排列
as you look through it you notice that it isn't uniform,
你會發(fā)現(xiàn)陽光的組成并不一致
that there are places that are darker.
有些地方比較暗
Each of those dark lines is due to a specific chemical element.
這些暗沉的線條都代表著特定的化學(xué)元素
Each element has its own series of lines that are specific to it.
每一種元素都擁有一系列專屬的線條
Each chemical element absorbs light at specific frequencies
每種化學(xué)元素都會吸收特定頻率的光線
removing a strip from the spectrum.
進而移除光譜上的特定區(qū)塊
As the light passes through the sun,
光線穿過太陽時
all the elements leave their mark.
所有的元素都會留下它們的印記
So when the light arrives at the Earth it contains
所以抵達地球的光線
the complete chemical formula of the sun.
包含了太陽的完整化學(xué)式
If we take the spectrum and spread it out to fine details
若是把光譜攤開…
and what we've done here is stacked up
我們在這里
pieces of the spectrum one on top of each other
把幾塊光譜上下堆疊
you see all of these dark areas.
你們可以看到這些暗色區(qū)域
The key to figuring out how much of these elements
至于判定元素含量的關(guān)鍵
are there is the breadth and the depth of the line;
則是這些線條的寬度和深度
how dark is the line and how broad is it.
也就是它們的深淺和寬窄