What the Discovery of Exoplanets Reveals About the Universe | Jessie Christiansen | TED

譯者: Winston Chung 審譯者: Shelley Tsang 曾雯海

I am a planet hunter

我是個行星獵人

and keeper of the keys at NASA's Exoplanet Archive.

也是NASA（美國太空總署） 太陽系外行星檔案保管鑰匙的人。

In March 2022, we reached a major milestone in space exploration:

在2022年3月，我們達到 太空探險的一個主要的里程碑：

5,000 known exoplanets.

5000個已知的系外行星。

For thousands of years,

幾千年來，

we've wondered about planets outside of our solar system,

我們一直都想知道太陽系外的行星，

now called exoplanets.

現在稱為系外行星。

But our technology only recently caught up with our imaginations.

但是我們的科技直到最近 才趕上我們的想像力。

And yes, 5,000 planets is incredible.

是的，5000個行星是很驚人的。

What's even more incredible

更驚人的是

is how space research will change as a result.

這結果將如何改變太空研究。

When I started grad school,

當我開始讀研究所時，

there were about 100 known exoplanets,

有100個已知的系外行星，

all radically different from the Earth and from each other.

每個都和地球截然不同， 而且它們彼此也截然不同。

I was determined to find more.

我下決心要找到更多。

I spent four years looking at nearly 87,000 stars, one by one.

我花了4年觀測幾乎87000個星球， 一個一個看。

Now you might have this romantic idea

也許你會浪漫地想

that I was gazing intently through a telescope,

我用望遠鏡仔細地觀察，

pondering some gorgeous view of the universe.

琢磨一些宇宙的美景。

I was not.

我不是。

I was looking at data like this,

我是看像這樣的數據，

measuring the brightness of each star over time.

衡量每個星球在不同時間的亮度。

If the brightness dipped, just briefly, just a little bit,

如果亮度只有在短時間 減低了只有一點，

it could be because a planet had orbited in front of that star,

那可能是因為有一顆行星 從這星球前面運行過去，

blocking some of the light from reaching my telescope.

擋住了一些射向我們望遠鏡的光線。

So I spent four years looking for decimal-level changes in these data.

所以我花了4年看這些數據裡 小數點以下的改變。

And after four years, I'd found ...

經過4年後，我找到

nothing.

什麼都沒有。

Zero exoplanets.

零顆系外行星。

Thankfully, they still gave me the PhD, I think, for effort.

很感謝地，他們仍然頒發博士學位給我， 我想，為了獎勵我的努力。

(Laughter)

（笑聲）

Then I moved to Harvard, where I worked on my first NASA mission, called EPOXI.

然後我搬到哈佛從事我第一個 太空總署的任務，叫做EPOXI。

I still didn't find any exoplanets.

我仍然沒有發現任何系外行星。

Then in March 2010, I joined the Kepler Mission,

然後在 2010 年 3 月 我參加開普勒任務，

NASA's grand experiment

那是太空總署的超大型試驗

with putting one of our planet-hunting instruments into space.

把其中一個追蹤行星的儀器放到太空。

Monday was my first day on the base in Silicon Valley.

星期一是我在矽谷基地 第一天上班。

It was mostly spent in HR.

大部分時間都花在人事作業。

Tuesday, I sat down and looked at the data for the first time,

星期二，我第一次坐下來 研讀那些數據，

and I found my first exoplanet.

我發現了我的第一個系外行星。

(Cheers)

（歡呼）

(Applause)

（鼓掌）

A few minutes later, I found another one.

過了幾分鐘，我找到另外一個。

There's a saying that we're the generation that was born too late to explore Earth

曾經流傳一句話， 我們這一代要去探險地球生得太晚，

and too soon to explore space.

但要去探險太空卻生得太早。

That's not true anymore.

這句話不再是真的。

That day and every day since, I've gotten to explore space.

從那一天起和之後的每一天， 我都在探險太空。

Kepler made it possible for us

開普勒讓我們能夠

to measure stellar brightness much more precisely

遠比以前更精準地衡量 星球的亮度。

than we had before.

And eventually I helped find thousands of exoplanets.

終於我幫助找到上千的系外行星。

And we've really only searched our local corner of the galaxy

而且我們只是在我們銀河系裡 鄰近的角落找到這些行星。

to find those planets.

That means there's likely tens of billions of planets just in our Milky Way.

這意味著在我們所屬的銀河 就可能有幾百億顆行星。

Now with so much data,

現在我們有這麼多數據，

we can start sorting and grouping and categorizing these planets

我們可以開始把這些行星 整理分類找到特性和趨勢。

to find trends.

Think of it this way:

用個比喻去了解：

if you wanted to learn about dogs and you had five dogs in your study,

如果你想研究狗 而你有五隻狗可供研究，

well, you'd learn a lot about those five dogs.

你就學到很多有關這五隻狗的事。

That they're all good dogs.

它們都是好狗。

But maybe not about dogs in general.

但是不見得是對一般狗都適用。

If you had 5,000 dogs in your study,

如果你有 5000 隻狗可研究，

then you’d start to see that there were German Shepherds and Dobermanns

你就開始看到有德國牧羊犬， 杜賓犬和小獵犬，

and beagles,

and that these different breeds have different features.

而這些不同種類的狗 有不同的特徵。

With demographic-level data on exoplanets,

有了系外行星基本屬性的數據，

we can start asking some of these big questions for the first time,

我們開始能問一些比較大的問題，

like: Of those thousands and billions of planets in our galaxy,

像：我們銀河系裡幾千幾億的行星裡，

how many are like the Earth, or like Jupiter?

有多少是像地球，或像木星？

How many planets does a typical star have?

一個恆星通常有幾個行星？

Can a planet orbit more than one star?

一個行星能繞行多於一個星星嗎？

Yes.

能的。

Can a planet exist without any star at all?

一個行星沒有恆星能存在嗎？

Also yes.

也能。

One surprising result from the study of planet populations

從這行星分佈研究得到 一個令人驚訝的結果

is that the most common kind of planet in our galaxy

就是在我們的銀河最常見的行星

might be one we don’t have in our solar system:

可能是我們在太陽系沒有的：

a super-Earth up to twice as big and ten times as heavy as our Earth.

一個比地球兩倍大 而十倍重的超級地球。

We've found evaporating planets, disintegrating planets,

我們曾發現正在蒸發的行星， 正在解體的行星，

planets clustered together in a clockwork dance,

聚集在一起有規律地跳舞的行星，

ultra-puffy planets, ultra-dense planets.

極端鬆散的行星，極端緊密的行星。

It's truly a wild and wonderful menagerie

我在太空總署收集的系外行星檔案 實在是荒野而奇妙的展覽場。

that I get to corral at the NASA Exoplanet Archive.

But it gets even more interesting than that.

有趣的不止於此。

With so much data, we might finally be able

有了這麼多數據，我們可能終於能

to figure out how planets are made.

明白行星是如何形成的。

We see baby stars being born in stellar nurseries

我們看到嬰兒星星在 恆星的育嬰室出生

surrounded by dust and gas.

有灰塵和氣體環繞。

And we see all the stars surrounded by completed planetary systems.

我們看到很多星星有 完整的行星系統圍繞著它們。

But we still don't really know what happens in between.

但是我們仍然不明白 這兩者之間發生了什麼事。

With more data, we might find planets

有了更多的數據， 我們可能發現一些行星

at some middle stage or many middle stages.

在兩者之間的 一個或許多階段。

And from there, be able to map out a timeline of planetary development.

從那裡，我們可能可以推導 行星隨時間的演化。

What triggers these diffused clouds of dust and gas to collapse and transform?

什麼事使這些游離的灰塵和氣體雲 聚集起來而有轉變？

And how does the chaos and turmoil of dust become pebbles,

這些散漫混亂的灰塵如何變成小石頭，

and pebbles become boulders, and boulders become planetesimals?

然後小石頭變成巨石， 而巨石變成板塊？

And from there,

而且從那裡，

after an intense series of bombardments

經過一系列的撞擊

eventually settle into an ordered series of planets.

終於穩定形成有規律的行星系。

How often is one of those planets solid and warm,

有多常見到一個行星是固態而溫暖，

with a water ocean lapping a sandy shore?

有水的海洋接連沙灘海岸？

Where do we come from, and how did we get here?

我們哪裡來的，怎麼來到這裡？

The more we learn about exoplanets,

我們學到愈多關於系外行星的事，

the easier it is to target the ones we want.

我們就更容易專注我們要的目標。

So far, we haven't found any planets that are like the Earth.

到目前為止，我們還沒有找到 像地球一樣的行星。

But I hope we will.

但我希望我們會找到。

NASA just spent the last few years

太空總署在過去這幾年

studying the idea of a very large telescope in space

一直在研究一個想法 要把一個非常大的望遠鏡放在太空

with next-generation technology that would allow us to take an image,

用新世代的科技可以直接

an actual photograph, of a planet like the Earth.

為像地球一樣的行星照相。

With that photo, we could search for biomarkers, signatures of life.

有了相片，我們可以尋找生物特徵， 生命的跡象。

I'll probably spend the rest of my career working on that mission.

我可能會把我往後所有的工作生涯 都投入那個任務。

I hope I get to take that photo.

我希望我有機會可以照那照片。

Thank you.

謝謝。

(Applause)

（掌聲）