for habitation.

為居住。

But new research reveals that massive doses of radiation might actually be essential for

但新的研究顯示，大劑量的輻射實際上可能是必不可少的。

life outside our solar system.

太陽系外的生命

Okay, let's clarify here.

好吧，我們在這裡澄清一下。

Water makes possible all the chemical reactions for life here on Earth.

水使地球上所有的生命化學反應成為可能。

So when we're looking for other life out in the universe, it's widely thought that

所以當我們在宇宙中尋找其他生命的時候，人們普遍認為

the absolute most important thing a planet needs is… something like water.

一個星球最重要的東西絕對是... 像水這樣的東西。

That can be any kind of liquid solvent, or a substance that other things dissolve into.

那可以是任何一種液體溶劑，或者是其他東西溶解進去的物質。

Because of this, it's long been thought that a planet needs to be the right distance

正因為如此，人們一直認為，一顆行星需要合適的距離。

from its star in order to be considered 'habitable' — kind of a Goldilocks situation: not too

的恆星，才能被認為是 "可居住的"--這有點像金髮姑娘的情況：不太會被認為是 "可居住的"。

close to fry in the heat of that star and have all its water sizzle off, and not so

在那顆星辰的高溫下，近乎煎熬，其水都會被燒掉，而不至於像這樣

far that it's left out in the cold with only frozen water.

以至於在寒冷的環境中只剩下冰凍的水。

This ideal distance from a star is what we call the 'habitable zone.'

這個與恆星的理想距離就是我們所說的 "可居住區"。

Many organizations, including NASA, search for planets outside of our solar system, called

包括美國宇航局在內的許多組織，都在尋找太陽系外的行星，稱之為

exoplanets, that may exist in this zone as they're the most likely candidates for being

可能存在於這一區域的系外行星，因為它們是最有可能成為

able to host life.

能夠承載生命。

But new research turns that idea on its head.

但新的研究將這一想法顛覆了。

A team used modeling to find that at a certain size and with a high enough level of radioactive

一個團隊通過建模發現，在一定的規模和具有足夠高的放射性的情況下。

decay, a planet may not need a star to make it habitable—maybe it's keeping itself warm

衰變，行星可能不需要恆星來使它適合居住--也許它在保持自己的溫暖

instead.

而不是。

The key ingredient?

關鍵成分是什麼？

Radioactive forms of elements called radionuclides.

放射性形式的元素稱為放射性核素。

These are isotopes, or different kinds of familiar-sounding elements like uranium that

這些都是同位素，或者說是不同種類的元素，比如鈾，聽起來很熟悉，但它們都是同位素。

are radioactive.

是放射性的。

And while radiation often has a negative connotation for being damaging to living things and different

而輻射往往具有對生物和不同的生物有損害的負面含義。

kinds of radiation can cause damage to varying degrees, one essential thing about radioactive

種輻射會造成不同程度的損害，但有一點是必不可少的，那就是放射性物質會對人體造成傷害。

decay is that it releases heat.

衰變是它釋放出熱量。

In fact, there are all kinds of radioactive elements in Earth's crust and interior,

其實，在地球的地殼和內部存在著各種放射性元素。

and scientists actually estimate that about 50% of the heat given off by Earth is due

而科學家們實際估計，地球發出的熱量中，約有50%是因

to the radioactive decay of elements like uranium,  thorium, and potassium!

到鈾、釷、鉀等元素的放射性衰變!

Is it getting hot in here, or is it just me?

是這裡越來越熱了，還是隻有我這樣？

The team behind this latest news took that concept and asked the question: “Could this

這個最新消息的背後團隊帶著這個概念，提出了一個問題。"難道這

be enough to keep a planet without a star nice and toasty?”

足夠讓一個沒有恆星的星球保持良好的溫度嗎？"

They modeled three different sources of heat for a starless planet: radioactivity from

他們為一顆無星的行星建立了三種不同的熱源模型：來自宇宙中的放射性物質。

isotopes that take billions of years to decay, radioactivity from isotopes that only take

同位素需要幾十億年才能衰變，同位素的放射性只需要幾十億年的時間。

hundreds of thousands of years to decay, and heat left over from

幾十萬年的腐爛，以及殘留的熱能。

the planet's formation process.

行星的形成過程。

The scientists' model allowed them to plug in different planet sizes, ages, and radionuclide

科學家們的模型允許他們插入不同的行星大小、年齡和放射性核素。

abundances.

豐富。

Using the resulting calculated surface temperature, they then determined if that planet could

利用由此計算出的表面溫度，他們再確定該星球是否可以做到

host the life-giving liquid we're searching for.

寄存我們正在尋找的生命之液。

The solvents they considered were three of our Solar System's most common: water, ammonia,

他們考慮的溶劑是太陽系最常見的三種：水、氨。

and ethane.

和乙烷。

Their results show that warming a planet enough to host water in liquid form (without that

他們的結果表明，將一個星球升溫到足以容納液態水的程度（沒有那個

helpful heat from a star) would require about a thousand times more radioactive stuff, like

來自恆星的有用熱量）將需要大約一千倍以上的放射性物質，如

uranium and thorium, than we have on and inside the Earth.

鈾和釷，比我們在地球上和地球內部的。

That is a lot of radiation.

輻射量很大。

Their calculations also showed that Earth-sized planets with about one hundred times Earth's

他們的計算還表明，地球大小的行星，其體積約為地球的一百倍。

abundance of radionuclides could keep ethane liquid for hundreds of millions of years.

豐富的放射性核素可以使乙烷保持液體狀態達數億年之久。

This research suggests that when we're looking for exoplanets that could host life, we now

這項研究表明，當我們在尋找可能寄居生命的系外行星時，我們現在

may not only have to search for those in the habitable zone of a star,  but also radioactive,

可能不僅要尋找那些在恆星的可居住區，而且還要尋找放射性。

starless loners.

無星的孤獨者。

It brings up three key questions: could life survive in these huge doses of radiation?

它帶來了三個關鍵問題：生命能否在這些巨大劑量的輻射中生存？

Is it likely that a planet with this amount of radionuclides exists out there?

是否有可能存在一個有這麼多放射性核素的星球？

And if it does, could we find it?

如果有，我們能找到嗎？

As to the first question, it's kind of hard to picture the kind of multicellular life

至於第一個問題，很難想象多細胞生命的樣子

we're familiar with on Earth being able to withstand that kind of radiation.

我們熟悉的地球上能夠承受這種輻射。

But our world's most extreme microbes may be the perfect example.

但我們世界上最極端的微生物可能是最好的例子。

There's actually a bunch of bacteria that are totally chill with ionizing radiation,

其實有一群細菌，對電離輻射是完全冷淡的。

and then there's Cryptococcus neoformans, which is a radiotrophic fungus that actually

還有就是新隱球菌，這是一種輻射性真菌，實際上

eats radiation.

吃輻射。

And as for being able to find a planet like this, burning from the inside out with a radioactive

至於能找到這樣的星球，從內到外用放射性物質燒掉了

glow?

發光？

Only time will tell.

只有時間才能證明。

But with the latest generation of space telescopes being launched soon, like the James Webb,

但隨著最新一代的太空望遠鏡即將發射，比如詹姆斯-韋伯號。

we'll be able to keep an eye out—all thanks to research like this that told us what we

我們將能夠保持關注--這一切都歸功於這樣的研究，它告訴了我們什麼。

should be looking for in the first place.

應該首先尋找的。

If you want more on exciting exoplanet finds, check out this video here.

如果你想了解更多精彩的系外行星發現，請看這裡的視頻。

Keep coming back to Seeker for all your extraterrestrial hypotheses.

繼續回到Seeker來尋找你所有的外星假設。

If you have another astrobiological headline you want us to cover, let us know down in

如果你有其他天體生物學的頭條新聞想讓我們報道，請在下面告訴我們。

the comment below and as always, thanks so much for watching.

下面的評論，一如既往地感謝大家的觀看。

I'll see you next time.

下次見。