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Nothing in space is more important to our daily lives than the Sun.
太空中没有什么比太阳对我们的日常生活更重要了。
Next time you look out the window and don’t see a lifeless, frozen wasteland, you know our favorite ball of gas is still chugging along.
当你望向窗外，看到的不是死气沉沉的冰冻荒原，你就知道我们最喜欢的气体球还在昼夜不停地运转着。
But, seriously, life on Earth depends on the steady nature of our star.
但是，严肃地说，地球上的生命取决于恒星稳定的性质。
Here’s the thing, though: We don’t know if the Sun was always this consistent.
但问题是:我们不知道太阳是否一直如此稳定。
Scientists have only been able to track its activity back thousands of years, and it’s been around for almost 4.6 billion.
科学家们只能追踪它几千年前的活动，而它已经存在了近46亿年。
So is the Sun going to stay this steady in the future?
那么未来太阳还会保持稳定吗?
Or are we just in the middle of a convenient calm period?
还是我们正处于一段有利的平静期?
At this point, it’s impossible to know, but recently, an international team of scientists searched thousands of other stars to try and find out.
关于这一点，我们不可能知道答案，但最近，一个国际科学家小组搜索了成千上万的其他恒星，试图找到答案。
And their work, which was published on May 1st in the journal Science, reveals just how much we still don’t understand about this fundamental object.
他们的研究成果发表在5月1日的《科学》杂志上，揭露了我们我们有多不了解这个基本物体。
One tool they used in this study might surprise you:
他们在这项研究中使用的一个工具可能会让你吃惊:
NASA’s Kepler Space Telescope, which was retired in 2018.
NASA的开普勒太空望远镜，已于2018年退役。
We usually talk about Kepler finding planets outside the solar system, but some of its most important work was understanding the stars those planets orbit.
我们通常会在谈论寻找太阳系外的行星时提到开普勒，但它一些最重要的工作是了解有行星围绕运行的恒星。
After all, Kepler found planets using the transit method, which watched for a dip in a star’s light as a planet moved in front of it.
毕竟，开普勒是利用凌日法发现行星的。凌日法是观察行星在其前面移动时恒星光线的变化。
But that really only works if you understand the star’s natural variations in brightness.
但这只有在你理解了恒星亮度的自然变化后才行得通。
Kepler could watch around 150,000 stars at the same time, making it a hero for researchers — including those from this new paper.
开普勒可以同时观测大约15万颗恒星，这让它成为了研究人员的英雄——包括这篇新论文中的研究人员。
In the study, astronomers searched Kepler’s dataset, plus some supplementary data from the Gaia spacecraft, looking for stars that closely resemble the Sun.
在这项研究中，天文学家搜索了开普勒的数据集，以及盖亚宇宙飞船的一些补充数据，寻找与太阳相似的恒星。
And they ended up with 369 that roughly matched the Sun’s combination of temperature, age, composition, and rotation period.
最后他们得到了369个与太阳的温度、年龄、成分和自转周期的组合大致匹配的恒星。
That last one is actually especially important because a star’s rotation is responsible for the creation of its magnetic field.
最后一点其实特别重要，因为恒星的旋转是它产生磁场的原因。
And the Sun’s magnetic field produces sunspots, which are a big factor in driving changes in brightness.
太阳磁场会产生太阳黑子，这是太阳亮度变化的一个重要因素。
On the Sun, these fluctuations are small, averaging around 0.07 percent.
在太阳上，这种波动很小，平均约为0.07%。
But the average fluctuation in the similar stars was around five times bigger than that.
但相似恒星的平均波动大约比这个大五倍。
From this, you might conclude that our Sun is at some sort of activity minimum and that we should expect things to get more unpredictable in the future.
由此，你可能会得出这样的结论:我们的太阳正处于某种活动最低值时期，我们预计未来的事情会变得更加不可预测。
But there’s another piece to the puzzle.
但这个事情还有另一面。
The team also looked at another 2500 stars that matched the Sun’s age, temperature, and composition, but whose rotation periods Kepler wasn’t able to estimate.
该团队还观察了另外2500颗与太阳的年龄、温度和成分相匹配的恒星，但开普勒无法估计出它们的自转周期。
And the activity on those stars was much more like what we see on the Sun.
这些恒星上的活动与我们在太阳上看到的更为相似。
So, what gives? Well, it’s possible that this larger group, and the Sun, are somehow fundamentally different than their more active counterparts.
所以，到底是什么情况呢？可能是这个更大的星系群，还有太阳，在本质上不同于它们更为活跃的对手。
Or it could be that stars like the Sun are usually pretty quiet, but are capable of periods of more intense activity.
也可能是像太阳这样的恒星通常非常安静，但也有更剧烈的活动周期。
Either way, there’s no need to go out and build a bunker.
不管怎样，我们还没必要去建地下掩体。
As best as astronomers can tell, these are changes that play out over thousands or even millions of years.
就天文学家所知，这些变化持续了数千年甚至数百万年。
So it’s important to know in the grand scheme of things, but your weekend sunbathing in the backyard is going to be just fine.
所以重要的是要了解事情的大体情况，不过你周末在后院晒晒太阳是完全没问题的。
Speaking of the search for exoplanets, astronomers are starting to look not just for planets in general,
说到寻找系外行星，天文学家们不仅要寻找一般的行星，
but specifically for ones that might be habitable.
还要格外注意那些可能适合居住的星球。
That word might conjure visions of blue skies and oxygen-rich air, but… that’s probably not always true.
这个词可能会让人联想到蓝天和富含氧气的空气，但并不一定总是这样的。
According to a study published Monday in Nature Astronomy, maybe scientists ought to be looking in more exotic places.
根据周一发表在《自然天文学》杂志上的一项研究，科学家或许应该在更加奇特的地方进行观测。
This work is part of the field of astrobiology, which tries to understand what life off Earth might be like and how we could detect it.
这项工作是天体生物学领域的一部分，该领域试图了解地球以外的生命可能是什么样子，以及我们如何探测到它们。
For now, since there’s not a way to get to faraway planets, that detection is most likely going to have to come from biosignatures, which are chemical byproducts produced by life.
就目前而言，由于没有办法到达遥远的行星，那种探测最有可能源自生物特征，也就是生命产生的化学副产品。
Like, around here, cows and bacteria make methane, so if you’ve detected a bunch of methane over a field, you could infer something lived there.
比如，在地球上，奶牛和细菌会产生甲烷，所以如果你在一块土地上发现了甲烷，你就可以推断那里有生物。
A big goal of NASA’s upcoming James Webb Space Telescope is to search for these signatures in the atmospheres of nearby exoplanets.
NASA即将推出的詹姆斯·韦伯太空望远镜的一个大目标就是在附近系外行星的大气层中寻找这些特征。
But there are a lot of exoplanets so which ones should we consider habitable enough to study?
但是系外行星有很多，我们应该考虑哪些行星适合居住，值得我们研究呢?
To find out, this team took common microbes and put them in weird environments to see if they could grow.
为了找到答案，该团队将常见的微生物放在奇怪的环境中，看它们是否能生长。
They used E. coli and yeast, which represent two big classes of single-celled organisms, and they put them onto growth mediums inside glass bottles.
他们使用代表两大类单细胞有机体的大肠杆菌和酵母，并将它们放在玻璃瓶内的生长培养基上。
In one bottle, they left ordinary air, but in the others, they replaced that with either pure hydrogen, pure helium, or a mix of nitrogen and carbon dioxide.
在一个瓶子里，他们留下了普通的空气，但在其他瓶子里，他们留下的是纯氢、纯氦或者氮气和二氧化碳的混合物。。
Importantly, these test environments didn’t contain free oxygen, a key element most living things use to get energy.
重要的是，这些测试环境不含游离氧，而氧是大多数生物获取能量的关键元素。
After allowing the microbes time to grow, they checked the bottles to see what happened.
让微生物生长一段时间后，他们检查瓶子看看发生了什么。
And amazingly, in every case, both the yeast and E. coli could reproduce.
令人惊奇的是，每一次酵母和大肠杆菌都能繁殖。
E. coli can switch to an alternate metabolism that doesn’t require oxygen, so it fared the best, producing a little less than half the growth seen in the regular-air bottle.
大肠杆菌可以转换成一种不需要氧气的替代代谢，所以它的表现最好，只产生略少于普通空气瓶一半的生长。
Yeast did substantially worse — but it still grew!
酵母的情况更糟，但它也在生长!
The most exciting takeaway, though, is that both could grow in an all-hydrogen atmosphere.
最令人兴奋的是，两者都可以在全氢的大气中生长。
That’s what makes up most of the atmosphere for planets like Jupiter and Saturn, and it’s also probably a key component in the atmospheres of many large, rocky exoplanets.
氢是木星和土星等行星大气的主要成分，也是许多大型岩石系外行星大气的关键成分。
What’s even better is that, since hydrogen is so light, the atmospheres containing it are usually large and fluffy, making them easier for telescopes like the James Webb to study.
更妙的是，由于氢很轻，含有它的大气层通常又大又蓬松，这能让像詹姆斯·韦伯这样的望远镜更容易研究它们。
Also, when the team looked at the gasses released by E. coli during the experiment, they found dozens of different molecules, including several already considered prime biosignatures.
同时，当研究小组观察大肠杆菌在实验过程中释放的气体时，他们发现了数十种不同的分子，包括一些已经被认为是主要生物特征的分子。
All this doesn’t mean that we’re likely to find E. coli on another planet, but it does suggest life is even more adaptable than we thought.
所有这些并不意味着我们可能会在另一颗行星上找到大肠杆菌，但这确实表明生命的适应性比我们想象的更强。
Which is great news for astrobiologists, because so far, we haven’t found a ton of truly Earth-like planets.
这对天体生物学家来说是个好消息，因为到目前为止，我们还没有发现大量真正的类地行星。
But maybe we didn’t need to, after all!
但也许我们根本不需要这么做!
Thanks for watching this episode of SciShow Space News!
感谢收看本期太空科学秀!
If you want to learn more about exoplanets and the life that could thrive on them, you might enjoy our Exoplanets playlist.
如果你想了解更多关于系外行星和在系外行星上繁衍的生命，你可能会喜欢我们的系外行星播放列表。
Right now, it’s got more than forty episodes in it… so if you’re looking for a break from Earth these days, we’ve got you covered.
现在，它已经有四十多集了……所以如果你想逃离地球一会儿，我们为你提供了相关内容。
