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Fifteen years ago, the Galileo spacecraft plunged into Jupiter's atmosphere, ending its eight-year mission studying the planet and its moons.
15年前，伽利略号宇宙飞船坠落进木星的大气层，结束了长达8年的任务，即探测木星及其卫星。
But that doesn't mean it stopped sharing the system's secrets.
但这并不意味着这艘宇宙飞船就无法再分享与木星有关的奥秘了。
As reported in a paper published this week in Nature Astronomy,
本周，《自然天文学》杂志上发表了一篇论文：
researchers found something new and surprising hiding in data Galileo captured all the way back in 1997:
研究人员发现，1997年伽利略号捕捉到的数据中隐藏着令人惊愕的新发现：
evidence of water plumes on one of Jupiter's moons, Europa!
木卫二上有羽流存在的迹象！
According to a new computer model, while you were breaking in your Nintendo 64, this spacecraft might've been quietly observing water on another world.
根据新的计算机模型，在游戏迷们沉浸于任天堂64之际，伽利略号可能一直都在静悄悄地观察着木星卫星上的羽流。
If plumes on Europa sounds familiar, it might be because there's another moon with water plumes whose name also starts with an E: Enceladus.
如果大家觉着木卫二的羽流听着很熟悉的话，这或许是因为另一个卫星上也有羽流存在的迹象，而且这个卫星的名字也是以E打头的：土卫二。
It orbits Saturn, and we've talked about it here before.
土卫二是土星的卫星，在我们的节目中已经多次提到过它了。
Europa is about six times bigger though, around the same size as our Moon, and data suggest it has twice as much water as the Earth does.
虽然木卫二的体积是土卫二的六倍，跟月球差不多大，但数据显示，木卫二的大小是地球的二倍。
It's enough for a global, underground ocean, but we've never actually had definitive proof that it's down there.
如此大的羽流含量足以承载地球上所有的地下海洋了，但我们一直没有确凿的证据表明羽流确实存在其中。
To do that, well, we'd need to find something like plumes.
要证实这一点，我们需要寻找与羽流类似的东西。
As early as 2012, we had some hints from the Hubble Space Telescope that they might exist, and we've compiled even more evidence over the years.
早在2012年的时候，通过哈勃太空望远镜，我们得到一些蛛丝马迹表明羽流可能存在，而且在其后的数年间，我们也积累了更多的证据。
But because all these measurements were done at the very limit of Hubble's sensitivity, their accuracy is debated.
但由于所有测量都要受到哈勃太空望远镜灵敏度的限制，所以测量的准确度还有待商榷。
To solve this mystery, we need better data, ideally, something closer to the source.
为了解开这个谜团，我们需要更精确的数据，离木卫二越近的数据越理想。
Unfortunately, Juno, our spacecraft currently orbiting Jupiter, doesn't have the equipment to study these features.
不幸的是，现在环绕木星的宇宙飞船朱诺号不具备研究这些性征的设备。
In fact, it was launched before any evidence of plumes had been discovered.
实际上，在朱诺号发射之后，才有了羽流存在的蛛丝马迹。
So we can't give the local help a side quest. The good news though, is we had our old friend Galileo!
所以我们无法在朱诺号发射后再向它安排支线任务了，不过好在我们的老朋友伽利略号还没有退伍！
Likely inspired by those Hubble discoveries, a team of astronomers recently gave the 20-year-old data another look.
受到哈勃太空望远镜发现成果的启发，最近，一组天文学家从另一个角度诠释了20年前的数据。
And we're glad they did. During its flyby of Europa, Galileo got as close as 206 kilometers from the moon's surface,
他们的成果让人欣喜，在近地探测木卫二期间，伽利略号最近抵达了距离木卫二206km的地方，
and it measured changes in Europa's magnetic field strength and distribution of plasma.
并测量到了木卫二磁场强度和等离子体分布情况的变化。
Now, we think those changes could easily be explained by the presence of a plume, one maybe around 1000 kilometers wide and at least 200 kilometers tall.
如今，我们认为，这些变化可以通过羽流的存在得到解释，这种羽流的宽度可能有1000km，高度至少有200km。
At least that's what the team's computer models suggest.
至少该研究小组的计算机模型得出的是这样的结果。
And if this turns out to be true, it would be a huge bonus for space exploration.
如果这一切都是真的，那么对于空间探索来说将会是巨大的福利。
After all, it means that if we sent a mission to Europa, we'd be able to sample its oceans without drilling through kilometers of ice.
毕竟，这意味着：如果发射宇宙飞船到木卫二的话，我们就能够得到木卫二海洋的样本，而且也不必掘地三尺。
But this is only one model, so we'll need more evidence to be sure.
但这只是一个模型而已，所以我们需要更多的证据来印证。
And ultimately, our best chance of confirming Europa's plumes is still sending a craft back to Jupiter that's capable of detecting them.
但最终，最能证实木卫二是否存在羽流的依然是发射飞船到木星，让飞船进行探测。
Which, of course, astronomers are already working on.
当然了，天文学家已经着手于此了。
NASA's Europa Clipper mission is slated to launch in the 2020s, and it'll have nine instruments to help study the plumes' composition, like a mass spectrometer.
美国宇航局的木卫二飞剪将在本世纪20年代开启。木卫二飞剪将配备9种仪器来助力研究羽流的组成，就像质谱仪一样。
There may also be a lander in the works, if it gets the funding. And an ESA mission dubbed JUICE should launch in 2022.
届时，着陆器可能也会参与其中，前提是经费充足，2022年，欧洲航天局的木星冰月探测器也将开启。
When it reaches Jupiter around 2030, it'll study Europa,
等2030年木星冰月探测器抵达木星后，
as well as two of Jupiter's other moons astronomers believe have some liquid water under their surfaces:
就会着手研究木卫二以及木星的另外两个卫星。因为天文学家认为，另外两个卫星的表面下也有液态水的存在。
Ganymede and Callisto. So, we'll just have to wait and see.
这两个卫星就是木卫三和木卫四，就让我们拭目以待吧！
Meanwhile, here's some news we had to wait over 13 billion years to see, light from some of the very first stars in the universe.
还有一些消息是我们要再等130亿年才能看到的，那就是宇宙初期一些恒星所发出来的光。
A paper published in Nature this week reports the discovery of stars forming in a distant galaxy as early as 250 million years after the Big Bang,
本周，《自然》期刊上发表了一篇论文，这篇论文提到发现了宇宙大爆炸2.5亿年后某遥远星系形成的一些恒星，
when the universe was only 2% its current age.Using an array of radio telescopes called ALMA,
那时候宇宙的年龄只有现在的2%，通过使用最新射电望远镜(ALMA)，
an international team of astronomers was able to analyze the light coming from stars in the galaxy dubbed MACS1149-JD1.
某国际天文学家小组得以分析MACS1149-JD1星系的恒星发出来的光。
Based on how fast the galaxy is moving away from us, they estimated its light to be about 13.3 billion years old;
根据该星系远离地球的速度，这些天文学家估测，这些光大概是133亿年前发出的，
only 500 million years younger than the universe itself.
也就是宇宙形成5亿年后发出的。
They could make this estimate because the universe is expanding, so galaxies farther away,
他们之所以能做出这样的估测是因为宇宙是不断扩张的，所以距离我们越远的星系，
and therefore older, are moving away from us faster than the ones nearby.
年龄就越大，其速度就越快。
And we can detect those speeds based on what the light from these galaxies looks like.
此外，我们还可以根据这些星系所发出光线的样子来检测其传播速度。
Of course, if the galaxy has light, it probably means it has stars, too.
当然了，如果这个星系有光存在，也就有恒星了。
And since they couldn't just suddenly pop into existence, it means they have to be even older than 13.3 billion years.
而由于形成恒星绝非一眨眼就能完成的事，所以这些恒星的年龄绝对不止133亿年了。
The researchers figured out their age by modeling when early bursts of star formation had to have happened in order to make the galaxy's light signature,
这些天文学家判断恒星的年龄是通过建模的方式，也就是在星系光谱得以匹配数据的情况下
also called its spectra, match their data.
对恒星形成过程中星爆的发生点进行建模。
They found there had to be a bunch of stars forming around 300 million years prior to the light we're seeing now.
结果是，他们发现，在我们所看到的光发出之前的3亿年前，已经有许多恒星形成了才可以。
And that means most of the stars themselves, and therefore the galaxy as a whole, was forming only 250 million years after the universe came to be.
也就是说，大多数恒星本身，甚至整个星系，都是在宇宙形成后的仅2.5亿年间形成的。
Besides being cool to know about, this discovery is good news for anyone trying to study the universe's first generation of stars,
这则令人惊叹的消息对于那些想要研究宇宙第一批恒星的人来说是好事，
because it suggests we have the tools to study them.
因为它表明我们是有工具可以辅助研究的。
We can figure out exactly when they started forming and what properties they have.
通过这些工具，我们可以精确得知恒星形成的时间点以及它们的特性。
And this is especially good news for one future mission: NASA's James Webb Space Telescope, which is designed to study the early universe.
这对于未来的一项任务来说大有裨益，那就是美国宇航局的詹姆斯·韦伯太空望远镜，设计该望远镜是为了研究宇宙形成初期的。
So when it finally launches, it looks like it has yet another target to train its sights on.
该望远镜落地实施后，似乎还有另一个目标要完成。
All it has to do now is go to space. Clearly, a lot of astronomy involves waiting.
不过现在的第一步是进入太空，显然，天文学的进展离不开耐心的等待。
Thanks for watching this episode of SciShow Space! If you can't wait for the next space news episode, it's okay:
感谢收看本期的《太空科学秀》！如果大家等不及想看下一期的话，可以这样做哦：
We have plenty of other stuff for you to learn about, like what would happen if the universe were shaped like a donut.
我们有很多资源可供大学了解，比如如果宇宙的形状与甜面圈类似的话会发生什么。
Because this is a thing astronomers think about.
因为这件事也是天文学家在思考的事。
