Orbiting our Sun at literally the perfect distance to support life, it kinda makes you wonder:

以完美的距離繞著太陽運行，以支持生命，這讓你很好奇。

Of these billions of planets, just how many other habitable worlds are really out there?

在這幾十億顆行星中，到底還有多少個可居住的世界呢？

Well, new research from NASA, the European Space Agency, and the SETI Institute

美國宇航局、歐洲航天局和SETI研究所的新研究表明

estimates that there could be close to 300 MILLION potentially habitable planets in our galaxy alone!

據估計，僅在我們的銀河系中，就可能有近3億顆潛在的宜居行星!

So, how did they settle on this number?

那麼，他們是如何確定這個數字的？

Well, first the researchers needed a set of great telescopes.

嗯，首先研究人員需要一套偉大的望遠鏡。

Enter NASA's Kepler space telescope and ESA's Gaia space observatory.

進入NASA的開普勒太空望遠鏡和歐空局的蓋亞太空觀測站。

Two missions, launched separately, but with a shared goal of making a huge DISCOVERY!

兩項任務，分別發射，但共同的目標是進行一次巨大的發現！

The aim of NASA's Kepler mission was to literally stare into space searching for celestial bodies that varied in size, mass, and even orbit.

美國宇航局開普勒任務的目的，就是要實實在在地盯著太空，尋找大小、品質、甚至軌道都不同的天體。

By staring at one or even multiple patches of space, Kepler was able to identify a planet's characteristics through a process called the transit method,

通過盯著一塊甚至多塊空間，開普勒能夠經由過程所謂的過境法來辨認一顆行星的特性。

which when a planet breaks the line of sight between the observed star and the telescope.

當一顆行星打破了觀察到的恆星和望遠鏡之間的視線。

And to make this method as efficient as possible, scientists needed two major criteria met:

而要使這種方法儘可能高效，科學家需要滿足兩大標準。

an extremely dense field of view and a clear line of sight.

極其密集的視野和清晰的視線。

Basically, this meant that Kepler needed to continuously monitor the most star-rich patch of space possible

基本上，這意味著，開普勒需要持續監測最富含恆星的空間。

without being blocked by the Sun or Earth.

而不被太陽或地球所阻擋。

And what better place to look than the Cygnus and Lyra constellations,

還有什麼地方比天鵝座和天琴座更適合尋找。

known for their vast array of northern stars.

以其浩瀚的北斗星群而聞名。

Using the transit method, Kepler was able to collect data on over 530,000 stars during its nearly decade-long run before retiring.

利用過境方法，開普勒在退休前近十年的運行中，能夠收集到超過53萬顆恆星的數據。

This is where the recent work comes in.

這就是近期工作的意義所在。

Unlike previous studies, which mostly focused on findings from Kepler,

與以往的研究不同，以往的研究大多集中在開普勒的研究成果上。

teams from the SETI Institute, NASA, and ESA incorporated data gathered by Gaia.

來自SETI研究所、美國宇航局和歐空局的團隊整合了蓋亞收集的數據。

This mission, which has already observed and measured roughly 1 billion stars, is using a host of instruments to make a 3D map of the Milky Way.

這項任務已經觀測和測量了大約10億顆恆星，正在利用一系列儀器製作銀河系的3D地圖。

Its goal is to observe the location and brightness of stars by measuring the distances, positions, motions, and changes in a star's brightness.

它的目標是通過測量恆星的距離、位置、運動和亮度變化來觀測恆星的位置和亮度。

Using these data points along with Kepler's, scientists can now provide a more definite estimate of a planet's temperature

利用這些數據點和開普勒的數據點，科學家們現在可以對行星的溫度做出更明確的估計了

based on its distance from the host star.

根據其與主星的距離。

Which is absolutely critical when you consider what is necessary to host life on a planet.

當你考慮到在一個星球上生存所需的條件時，這絕對是至關重要的。

Too much heat and you get the scorching surface of Venus, while too little heat and you get the freezing temperatures of Pluto.

熱量太大，就會出現金星的灼熱表面，而熱量太少，就會出現冥王星的冰冷溫度。

So, for the seemingly perfect distance from a star, scientists look to the Goldilocks Zone, otherwise known as the Habitable Zone.

所以，對於看似完美的恆星距離，科學家們把目光投向了金絲雀區，也就是所謂的宜居區。

This region contains exoplanets which could possibly have liquid water on their surface... and could in theory support life!

這個區域包含的系外行星，其表面可能有液態水... 理論上可以支持生命！

So, let's do the math!

那麼，讓我們來算一算吧!

The team estimates that from the stars observed with similar characteristics to the Sun,

研究小組估計，從觀測到的具有與太陽相似特徵的恆星。

anywhere from 30% to 90% have Earth-like planets in their habitable zone.

30%到90%的地方都有類似地球的行星在它們的可居住區。

And looking at the Milky Way specifically, NASA estimates that there could be 4 billion stars similar to our Sun.

而具體到銀河系，美國宇航局估計，可能有40億顆恆星與我們的太陽相似。

Estimating with an extremely conservative success rate of 7 percent,

以極其保守的7%的成功率估算。

there could be close to 300 million habitable worlds in our solar system.

太陽系中可能有近3億個可居住的世界。

An estimation like this is exactly what scientists, like the ones that developed the Kepler mission, have been searching for.

這樣的估計，正是像開發開普勒任務的科學家們一直在尋找的。

And while the team from this latest study has confirmed a few thousand exoplanets that fit the criteria for habitability,

而最新研究的團隊已經確認了幾千顆符合宜居性標準的系外行星。

it would be extremely difficult to know if these planets actually do have life based on this data alone.

僅憑這些數據就很難知道這些行星是否真的有生命。

The teams will still be gathering data from Gaia until at least 2022, and following Kepler is NASA's TESS mission.

這些團隊至少在2022年之前仍將收集蓋亞的數據，而在開普勒之後是NASA的TESS任務。

But even now, I think it's safe to say that we might not be so alone in this massive universe.

但即使是現在，我想可以說，在這個龐大的宇宙中，我們可能並不那麼孤獨。