The story of 'Oumuamua, the first visitor from another star system | Karen J. Meech | TED

譯者: Helen Chang 審譯者: SF Huang

NASA's always on the lookout for possible asteroid collision hazards,

美國太空總署一直小心觀察著 潛在小行星碰撞的危險，

so the Pan-STARRS telescope is scanning the sky every night.

所以泛星計畫的望遠鏡 每晚都在掃描天空。

Each morning, candidate objects are examined by Pan-STARRS staff

每天早上，泛星計畫的工作人員 會檢查候選的對象，

and usually discovered to be no big deal.

通常沒發現什麼大不了的狀況。

But on October 19, 2017,

但是在 2017 年 10 月 19 日，

Pan-STARRS spotted an object moving rapidly between the stars,

泛星計畫發現一顆 在恆星之間快速移動的物體，

and this time the usual follow-up measurements of position and speed

而這次例行的後續追蹤 所測量出的位置和速度，

showed something completely different.

顯示出完全不同的東西。

By October 22nd, we had enough data

到 10 月 22 日，我們有足夠的數據

to realize that this object wasn't from our solar system.

瞭解到這物體並非來自我們太陽系。

Holy cow.

天啊。

That's when I got the phone call,

我接到電話，

the phone call that all solar system astronomers are waiting for.

是所有太陽系的天文學家 都在等待的電話。

Let me tell you how exciting this was.

讓我告訴你這多麼令人興奮。

(Laughter)

（笑聲）

NASA's been expecting to see an interstellar comet

美國太空總署一直期待看到 穿過太陽系的星際彗星，

pass through the solar system since the 1970s,

但自 20 世紀 70 年代 以來直到現在，

but until now, we'd never seen anything.

我們未曾見過任何東西。

Our own solar system is huge,

我們自己的太陽系很巨大，

so even getting a package from the nearest star system

即使從距離 4.4 光年的 最近星系接收包裹

4.4 light years away

would take over 50,000 years.

也需要 5 萬年。

So this is a really big deal.

所以這事至關重要。

The interstellar visitor entered our solar system

星際訪客從黃道面的上方

from above the plane of the planets,

進入我們的太陽系，

coming from the direction of the constellation Lyra,

來自天琴座（Lyra）的方向，

and it passed closest to the Sun on September 9th,

於 9 月 9 日經過近日點，

passing inside the orbit of Mercury.

經水星軌道內側穿越。

Now this isn't a particularly close approach or unusual distance.

這距離不算特別接近， 也不算非比尋常，

It's just much easier to see objects close by.

只是近距離觀察物體要容易得多。

On October 14th,

在我們發現它之前，

before we discovered it, it made its closest approach to the Earth,

它在 10 月 14 日最接近地球，

within about 15 million miles.

距離約在 1500 萬英里內。

This is really close by astronomical standards.

以天文的標準而言，是非常近的。

Now rather than call this by its unwieldy catalog name,

我們不用難懂的目錄名稱來稱呼它，

we briefly called it "Rama,"

我們簡稱它為「拉瑪」，

after the cylindrical spacecraft that passed through the solar system

那是亞瑟·查理斯·克拉克 1973 年的經典科幻小說裡

in Arthur C. Clarke's classic science fiction story in 1973.

穿過太陽系的圓柱形太空船的名字。

But this wasn't quite right either,

但這也不那麼合適，

so in honor of it being discovered by a telescope in Hawaii,

所以為了紀念夏威夷的望遠鏡發現它，

we consulted two experts on Hawaiian culture --

我們諮詢了兩位夏威夷文化專家，

a Hawaiian navigator and a linguist --

他們是夏威夷航海家和語言學家，

to propose a name.

提出一個名字。

And they suggested "'Oumuamua,"

他們建議「斥侯星」，

which means scout or messenger from the distant past reaching out to us.

意思是來自遙遠的過去， 向我們伸手的偵察員或使者。

Now this discovery was important for many reasons,

這個發現很重要的原因相當多，

but to me the most significant is for what 'Oumuamua can tell us

但對我而言，最重要的是

斥侯星可以告訴我們太陽系的過去。

about the past of our solar system.

The process of the birth of a new solar system and the growth of planets

新太陽系的誕生和行星生成的過程

can be a violent and messy business.

可能很猛烈、很混亂。

Leftover icy and rocky debris gets ejected from the new solar system

當巨大的行星穿過 形成它們的塵埃盤時，

as the giant planets migrate through the dusty disk

殘餘的冰冷岩石碎片

便被逐出這個新生的太陽系。

out of which they're formed.

Now have you ever felt an emotional chill,

你有沒有感受到一種情緒的寒意？

something that's so exciting that a shiver runs up and down your spine?

一種令人興奮的東西 讓你的脊椎上下顫抖？

Or something that's very emotionally moving?

或是某種情緒激動？

Well this was it for me.

對我來說就是這樣。

This was my wow moment.

這是我的驚嘆時刻。

We actually had a piece of material from another solar system

我們實際上有一塊 來自另一個太陽系的物質

coming close enough for us to observe.

近到讓我們能夠觀察它。

So what would you like to know about 'Oumuamua,

你想了解斥侯星

the very first visitor from another star system?

這另一星系的首位訪客那些事呢？

Well, I could think of a million things,

我可以想到一百萬件事，

but there's what you want and what you can have,

但是想要的和得到的是兩碼事，

and 'Oumuamua was moving away and fading very rapidly.

而斥侯星正迅速、逐漸地消失。

In the span of about a week,

在大約一周的時間內，

it had dropped in brightness by a factor of [10].

它的亮度下降到十分之一。

So this is about all the time we were going to have

一個星期就是我們能便於 研究它的全部時間。

to study it easily.

So we had to distill the process of getting telescope time --

因此我們必須快馬加鞭 取得使用望遠鏡的時間，

normally a very competitive, peer-reviewed proposal process

這個由同行評審的提案流程 通常競爭激烈，

that can take up to months --

審核期可能長達數個月，

down to less than a few days.

被縮減到短短幾天。

So began a "polite" competition for resources.

一場「禮貌」的資源競爭開始了。

OK, let me not mince words. It was a fierce battle.

好吧，我不再矯言了。 這是一場激烈的戰鬥。

We dropped everything,

我們擱下所有的工作，

working around the clock,

不分晝夜地

trying to craft perfectly crafted proposal words

試圖趕製出完美的提案，

to send to the observatory directors.

送交給天文台的主管們。

Well, good news. We got the time.

好消息。我們獲得了使用的時間。

Now, from a perfectly selfish point of view,

從一個完全自私的角度來看，

the first thing we might like to know is how massive 'Oumuamua is.

首先我們想知道斥侯星有多大。

Because after all, it passed very close to the Earth,

因為它畢竟曾非常接近地球，

and we didn't know about it until afterwards.

這是事後我們才知道的。

How bad would this have been had it not missed the Earth?

如果它擊中地球會多糟糕？

Well, the impact energy

衝擊的能量取決於 速度的平方乘以質量，

depends on the square of the velocity times its mass,

and the mass depends on how big it is and what it's made of.

質量取決於它的大小和組成。

So how big is 'Oumuamua, and what's its shape?

那麼斥侯星有多大，是什麼形狀？

Well, we can get this from its brightness.

我們可從它的亮度得知。

Now, if you don't believe me, think of comparing the brightness

如果你不相信我，

可以比較後院的螢火蟲亮度

of a firefly in your backyard

to the navigation lights on a distant airplane.

與遙遠飛機上的導航燈亮度。

You know the airplane is much brighter --

你知道飛機比較亮，

it just appears faint because it's so far away.

它的亮度顯得微弱只因為距離遠。

We're also going to need to know

我們還需要知道

how reflective the surface of 'Oumuamua is,

斥侯星表面的反射程度。

and we don't have any clue,

我們沒有任何線索，

but it's reasonable to assume it's very similar to small asteroids

但我們認為它與太陽系中的

小行星和彗星非常相似，

and comets in our solar system,

or in technical terms,

或以技術用詞來說，

something between the reflectivity of charcoal and wet sand.

它的反射率類似介於木炭和濕沙之間。

Nowadays, most of the big telescopes are used in what's called a service mode,

如今，大多數大型望遠鏡 採用所謂的服務模式，

meaning we have to carefully develop all the instructions

意思是我們必須仔細闡述所有的指令，

and send them to the telescope operator,

並將它們發送給望遠鏡操作員，

and then anxiously wait for the data to come back,

然後焦急地等待收回數據，

praying to the weather gods.

向天氣之神祈禱。

Now I bet most of you don't have careers

我敢打賭，你們大多數人的職涯

that critically depend on whether or not it's cloudy last night.

不取決於昨晚是不是陰天。

Well, we weren't going to get any second chances here.

我們不會有任何第二次機會。

Because the weather was great, 'Oumuamua decided not to be.

天氣很好，而斥侯星則否。

Its brightness wasn't constant.

它的亮度不恆定。

Now here we see 'Oumuamua racing between the stars.

我們看到斥侯星在星星間急駛。

It's centered in the middle.

中間就是它。

The stars are trailed out because the telescope is following its motion.

星星拖出尾巴， 因為望遠鏡追著斥侯星移動。

It started faint and then it got brighter, fainter, brighter, and fainter again,

它的亮度轉弱，再次變亮， 變暗，變亮，又變暗。

as sunlight is reflected off of four sides of an oblong object.

由於陽光從長方形物體的四面反射。

The extreme brightness change

極端的亮度變化使我們對其形狀

led us to an unbelievable conclusion about its shape.

產生了令人難以置信的結論。

As shown in this artist's impression,

正如這位藝術家的圖象所示，

'Oumuamua is apparently very long and narrow,

斥侯星顯然非常長而窄，

with an axis ratio of about 10 to one.

軸比約為 10 比 1。

Assuming it's dark, this means it's about half a mile long.

假設它很暗， 意思是它大約半英里長。

Nothing else in our solar system looks like this.

我們的太陽系中沒有像這樣的物體。

We only have a handful of objects that even have an axis ratio

我們只有少數幾個

軸比大過 5 比 1 的物體。

bigger than five to one.

So we don't know how this forms,

因此我們不知道這是如何形成的，

but it may be part of its birth process in its home solar system.

但可能是其太陽系 誕生過程中的一部分。

'Oumuamua was varying in brightness every 7.34 hours,

斥侯星的亮度每 7.34 小時變化一次，

or so we thought.

或者這是我們認為的數字。

As more data started to come in from other teams,

隨著其他團隊的數據開始加了進來，

they were reporting different numbers.

他們報告的數字不同。

Why is it the more we learn about something,

為什麼我們越了解某事，

the harder it gets to interpret?

就越難以解釋？

Well, it turns out that 'Oumuamua is not rotating in a simple way.

原來斥侯星不以簡單的方式旋轉。

It's wobbling like a top.

它像陀螺一樣搖擺不定。

So while it is rotating around its short axis,

因此，它圍繞短軸旋轉，

it's also rolling around the long axis

也圍繞長軸滾動，

and nodding up and down.

並且上下搖擺。

This very energetic, excited motion

這種充滿活力、活躍的運行方式，

is almost certainly the result of it being violently tossed

幾乎可以肯定它是從自己的太陽系

out of its home solar system.

被猛烈拋出的結果。

Now how we interpret the shape from its brightness

我們如何從亮度解釋形狀

depends very critically on how it's spinning,

關鍵取決於它是如何旋轉的，

so now we have to rethink what it may look like,

所以我們必須重新思考它的外觀。

and as shown in this beautiful painting by space artist Bill Hartmann,

正如空間藝術家比爾 · 哈特曼 這幅美麗的畫作所示，

we think that 'Oumuamua may be more of a flattened oval.

我們認為斥侯星 更可能是個扁平的橢圓形。

So let's get back to the energetics.

讓我們回到能量學。

What is it made of?

它的組成是什麼？

Well, ideally we would love to have a piece of 'Oumuamua

理想情況下，我們希望 帶塊斥侯星的碎片到實驗室，

into the laboratory, so we could study it in detail.

讓我們可以詳細研究它。

But since even private industry can't manage to launch

但是，由於在這情形下，

即使是私營企業

a spacecraft within a week

也無法在一周內成功發射太空船，

to something like this,

astronomers have to rely on remote observations.

天文學家不得不仰賴遠程觀測。

So astronomers will look at how the light interacts with the surface.

因此，天文學家研究 光線如何與表面相互作用。

Some colors may get absorbed, giving it a chemical fingerprint,

有些顏色可能被吸收， 留下化學指紋，

whereas other colors may not.

而其他顏色可能沒被吸收、沒指紋。

On the other hand, some substances may just reflect more blue

另一方面，某些物質可能只是

更有效地反射藍光或紅光。

or red light efficiently.

In the case of 'Oumuamua, it reflected more red light,

斥侯星的情況是它反射更多的紅光，

making it look very much like the organic rich surface of the comet recently visited

使它看起來非常像

羅塞塔號太空船最近訪問的彗星

by the Rosetta spacecraft.

所遇到的富含有機物的表面。

But not everything that looks reddish has the same composition.

但並非所有看起來偏紅的 東西，成分都相同。

In fact, minerals that have tiny little bits of iron in the surface

事實上，表面上含有少量鐵的礦物質

can also look red,

也可能看起來紅紅的，

as does the dark side of Saturn's moon Iapetus,

土星的月亮「土衛八」的 黑暗面正是如此，

shown in these images from the Cassini spacecraft.

這些圖像來自卡西尼號太空船。

Nickel-iron meteorites, in other words, metal,

鎳鐵隕石，換句話說，金屬，

can also look red.

看起來也紅紅的。

So while we don't know what's on the surface,

因此，我們不知道表面是什麼，

we know even less about what's on the inside.

對內部所知更少。

However, we do know that it must at least be strong enough

然而，我們確實知道 它必須至少要夠堅固，

to not fly apart as it rotates,

在旋轉時才不會分開，

so it probably has a density similar to that of rocky asteroids;

所以它的密度可能 與岩石小行星的密度相似，

perhaps even denser, like metal.

也許更密些，像金屬那樣。

Well, at the very least, I want to show you

我至少想展示美麗的彩色圖像之一，

one of the beautiful color images that we got

是我們的地面望遠鏡獲得的。

from one of the ground-based telescopes.

All right, I admit, it's not all that spectacular.

好吧，我承認，它不是那麼壯觀。

(Laughter)

（笑聲）

We just don't have the resolution.

只是解析度不夠。

Even Hubble Space Telescope

甚至哈伯太空望遠鏡 也沒有更好的視野。

doesn't present a much better view.

But the importance of the Hubble data was not because of the images,

但哈伯數據的重要性不在於圖像，

but because it extended our observations out

而是它將我們的觀察結果

to two and a half months from the discovery,

延伸到發現它之後的兩個半月，

meaning we get more positions along the orbit,

意思是我們獲得軌道上更多的位置，

which will hopefully let us figure out where 'Oumuamua came from.

有望讓我們弄明白斥侯星來自哪裡。

So what exactly is 'Oumuamua?

那麼斥侯星究竟是什麼？

We firmly believe it's likely to be a leftover archaeological remnant

我們堅信，它可能是

另一個行星系統誕生過程中 剩餘的考古遺跡，

from the process of the birth of another planetary system,

some celestial driftwood.

是天體的漂流木。

Some scientists think that maybe 'Oumuamua formed

一些科學家認為，也許斥侯星形成時

very close to a star that was much denser than our own,

很靠近一顆比我們太陽 密度更大的恆星，

and the star's tidal forces shredded planetary material

而那恆星的潮汐力

在它自己太陽系的歷史早期 就弄碎了行星物質。

early in the solar system's history.

Still others suggest that maybe this is something that formed

還有一些人認為

它可能是一顆恆星 在痛苦的死亡過程中形成的，

during the death throes of a star,

perhaps during a supernova explosion,

可能是在超新星爆炸的期間，

as planetary material got shredded.

行星的物質被粉碎了。

Whatever it is, we believe it's a natural object,

不管是什麼，我們相信 這是一個自然物體，

but we can't actually prove that it's not something artificial.

但實際上我們無法證明 這不是人為的東西。

The color, the strange shape, the tumbling motion

顏色、奇怪的形狀、翻滾動作

could all have other explanations.

可能有其他的解釋。

Now while we don't believe this is alien technology,

既然我們不相信這是外星人的技術，

why not do the obvious experiment and search for a radio signal?

為什麼不做明顯的實驗， 蒐索無線電信號呢？

That's exactly what the Breakthrough Listen project did,

這正是「突破聆聽」計劃所做的，

but so far, 'Oumuamua has remained completely quiet.

但到目前為止，斥侯星仍然完全安靜。

Now could we send a spacecraft to 'Oumuamua

我們現在可以將宇宙飛船送到斥侯星

and answer this question once and for all?

並一勞永逸地回答這個問題嗎？

Yes, we do actually have the technology,

是的，我們的確擁有這項技術，

but it would be a long and expensive voyage,

但那將會是個既貴又長的旅程，

and we would get there so far from the Sun

到達時，會離太陽那麼的遠，

that the final approach trajectory would be very difficult.

最終的接近軌跡將會極端困難。

So I think 'Oumuamua probably has many more things to teach us,

所以我認為斥侯星可能 還有很多東西要教我們。

and in fact there might be more surprises in store

事實上，隨著像我這樣的科學家 繼續使用這些數據，

as scientists such as myself continue to work with the data.

可能會有更多的驚喜。

More importantly, I think this visitor from afar

更重要的是，我認為這位遠到的訪客

has really brought home the point that our solar system isn't isolated.

確實帶回一個觀點：

那就是我們的太陽系並不孤立，

We're part of a much larger environment,

我們是更寬廣宇宙的一部分，

and in fact, we may even be surrounded by interstellar visitors

事實上，我們甚至可能 被星際訪客包圍著，

and not even know it.

只是自己不知道。

This unexpected gift

這個意想不到的禮物

has perhaps raised more questions than its provided answers,

所衍生的提問 可能比帶來的答案還更多，

but we were the first to say hello to a visitor from another solar system.

但我們首次

向另一個太陽系的訪客打招呼。

Thank you.

謝謝。

(Applause)

（掌聲）

Jedidah Isler: Thanks, Karen.

吉迪達 · 伊斯勒：謝謝，凱倫。 我當然非常喜歡這個話題。謝謝。

I of course enjoyed that talk very much. Thank you.

As I recall, we found it pretty late in its journey towards us.

我記得你說到，我們在 它行經我們的旅程後期才發現它。

Will future technologies like the Large Synoptic Survey Telescope

未來的大型天氣測量望遠鏡技術等等

help us detect these things sooner?

能幫助我們更早發現這些事情嗎？

Karen Meech: Yeah. We're hoping that we'll start to see a lot of these things,

凱倫 · 米區：是的。我們希望 之後會開始看到很多這類東西。

and ideally, you'd love to find one as it's approaching the Sun,

理想的情況是 在它正接近太陽時找到它，

because you want to have time to do all the science,

因為想爭取充裕的時間 做所有的科學研究。

or even more ideal,

甚至更理想的是 準備好一艘太空船，

you'd get a spacecraft ready to go,

parked somewhere in the L4 or L5 position,

停在 L4 或 L5 位置的某個地方，

somewhere near Earth,

停在靠近地球的某處，

so that when something comes by, you can chase it.

這樣有東西進來時， 就可以去追蹤它了。

JI: Awesome, thanks so much. Let's thank Karen again.

伊斯勒：太棒了，非常感謝。 讓我們再次感謝凱倫。

(Applause)

（掌聲）