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Over the last few decades, we've found evidence that various places in the solar system, like Mars or Saturn's moon Enceladus, could be or could have once been habitable.
过去几十年来，我们发现证据表明太阳系里的很多地方，比如火星或者土卫二，现在或者过去是宜居的。
But life on our Moon is a different story.
但地球的卫星月球却不宜居。
The Moon is a generally dry, irradiated wasteland, and it has been for billions of years.
总体而言，月球气候干燥，是受日光辐射的荒芜之地，几十亿年来都是如此。
Of course nothing's absolutely sure in science, but we're as confident as can be that today's Moon is lifeless.
当然了，从科学的角度讲，没有什么是绝对的，但我们很确信一点：月球目前并不宜居。
But a new paper published online last week in the journal Astrobiology says that it might not have always been that way.
但上周《天体生物学》期刊上发表了一篇新的在线论文，其中写道，月球以前可能是宜居的。
For a cosmic blink of an eye, just as life here was starting, it also could have survived on the Moon.
宇宙之初的月球可能是宜居的。
The problem with living on the Moon is that there are lots of problems.
在月球上生活有很多的问题要解决。
Depending on the temperature, any liquid water immediately either freezes or boils away to interplanetary space, because there's effectively no atmosphere to keep liquids, liquid.
月球上的液态水会随着温度的变化而立刻结冰或者蒸发到太空中去，因为月球的环境无法保留液态水。
And speaking of the temperature, days can be up to 127°C, while nights are about 300° colder.
提到温度，月球白天气温可达127°C，晚上的温度要比白天低近300°C。
No atmosphere or magnetic field also means there's nothing to block destructive solar radiation from raining down on the surface.
月球没有大气层，也没有磁场，也就意味着月球无法阻隔太阳具有杀伤性的辐射普照其表面。
There are some impressively hearty microbes, to be sure, but the Moon is a thoroughly difficult place to live.
月球上当然会有一些生命力旺盛的微生物，但其居住环境还是十分艰难的。
It probably wasn't always like this, though.
不过，很有可能月球环境并不是一直如此。
By collecting research from a huge range of disciplines, a pair of astrobiologists found that we've developed a picture of the very early Moon that, at times, seems downright habitable.
通过手机大量其他学科的研究成果，两位天体生物学家组成的小组发现，可以形成一张月球最初的图片，这张图片看起来环境十分宜居。
The first time was when the Moon formed about four and a half billion years ago.
第一次是在近45亿年前的月球。
As its rocks coalesced, they released huge amounts of heat and trapped gases.
月球上岩石合并的过程中，会释放出大量的热量，并喷薄出大量气体。
The second time was around half a billion years later, when another burst of lunar volcanic activity released more heat and gas.
第二次是在那之后的5亿年，当时月球发生了一次火山活动，也释放出了大量的热量和气体。
Both times, the gases could have stuck around for tens of millions of years, possibly forming an atmosphere thicker than the one around Mars today and allowing for liquid water on the surface.
这两次释放出的气体都在月球附近游荡了数千万年之久，很可能形成了大气层，其厚度要比今天火星的大气层更厚，这样，液态水便能存在于月球表面了。
And the Moon had a magnetic field back then, too, caused by moving molten rock deep beneath the surface, which would have helped block some of the most dangerous incoming radiation.
那时候的月球还有磁场呢，磁场之所以能形成是因为熔岩移动到了月球表面，这样就助力阻碍了十分危险的辐射。
The paper's authors also point out that all this was happening just as life was gaining a foothold down here on Earth.
这篇论文的两位作者还指出，发生这些变化的时候，地球上也正刚开始形成生命。
And even if scientists are right that the Moon's improved conditions wouldn't have lasted for very long, we already know that life here didn't take long to get going.
有些科学家认为，月球上的境况就算有所改变，也不会持续多久。这些科学家的说法即便是正确的，但我们已经知道：生命的适应性是很强的。
Some microbes could have even been blasted off Earth by asteroid impacts, only to land on the Moon and start things up there.
有些微生物可能通过小行星撞击的作用而被地球推向了月球，并落地生根。
Or the other way around.
事情也可能是反向发展的。
Of course, this isn't proof that there was ever life on the Moon;
当然了，这并不能证明月球上曾有生命存在。
but it certainly does give us a new view of our sweet little satelite.
但这确能让我们对地球的小甜心月球有一个新的了解。
Thankfully, life on Earth is much more stable.
谢天谢地，地球上的生命稳定性更高。
And a lot of that is because the Sun is usually pretty chill.
这主要是因为太阳没有咄咄逼人。
I mean, there's the occasional solar storm, but most days, the Sun just sort of sits there, warming your face and maintaining life.
我是说，有的时候，太阳会发生太阳风暴，但大多数时候，太阳只是静静地发光发热，维持地球的生命运转。
Except, it hasn't always been so peaceful.
不过，太阳并不总是和颜悦色的。
In this week's issue of Nature Astronomy, scientists studying some of the oldest rocks in the solar system report that when it was young, the Sun acted out a lot more.
在本周《自然天文学》上发表的文章中，研究太阳系古老岩石的科学家指出，太阳早些时候是十分活跃的。
Which, didn't we all?
不过，早期的时候，活跃度都很高啊。
It's hard to find physical records from the very early solar system, because there wasn't really anything here yet.
很难找到太阳系初期的切实证据，因为实在是没什么可找的。
So these days, a lot of our knowledge comes from a combination of well-tested models, observations of young stars, and more indirect evidence like the locations of planets.
所以进来，我们的很多新知识都是从经受住检验的诸多模型中得来的，从我们对年轻恒星的观察中得来的，从更为间接的证据（比如，行星的位置）中得来的。
We can also study tiny, ancient grains of rock buried within meteorites, but learning their secrets can be tricky business.
我们也可以研究陨石内部燕麦的古老岩石颗粒，但弄清其中的奥秘并非容易事。
For example, it can be hard to tell if elements in the grains have been there for billions of years, or if they formed through more recent radioactive decay.
比如，很难辨别出岩石颗粒里的成分是否有数十亿年的念头，也很难得知它们是否是通过最近的放射性衰变才得以形成的。
Together those methods do a fantastic job teaching us about our early environment.
将上述方法结合在一起，让我们受益良多，了解了很多初期宇宙的知识。
But scientists always want to get closer to the source.
但科学家总是想要更加的切近事实。
And this week, a team of physicists reported that by studying gases trapped within ancient minerals, they've found direct evidence of some of the Sun's earliest temper tantrums.
本周，一组物理学家称，通过研究掩藏在古老矿物质中的气体，他们发现有直接证据表明，太阳以前有多么的玩世不恭。
Or, as they're called in the paper, a phase of intense irradiation not recorded by minerals that formed later. Whichever works.
具体来说，他们在论文中指出，太阳曾经有一个时期里进行了剧烈的辐射，这种辐射并未在随后形成的矿物质身上体现出来。
The team studied a type of deposit known as CAIs, short for calcium-aluminum-rich inclusions, which are found in all sorts of meteorites.
该小组研究了一种沉积物，名为富含钙铝混杂物(CAI)，这种沉积物可以在各种陨石里找到。
Specifically, they focused on those found inside a meteorite that fell on Australia in 1969.
他们专注的这颗陨石是1969年掉落在澳大利亚境内的陨石。
That sample was full of hibonite crystals, a type of mineral, and likely formed more than 4.5 billion years ago.
该样本中富含黑铝钙石晶体，该晶体是一种矿物质，极有可能是45亿多年前形成的。
The CAIs are less than a tenth of a millimeter across, but those tiny grains were some of the first things to form in our solar system.
钙铝混杂物通体不过0.1毫米，但这些细小的颗粒却是太阳系里最初形成的物体。
And they're great records of our star's activity.
他们极好地记录了恒星的活动。
When the newly formed Sun gave off bursts of high-energy particles like protons, some protons would crash into atoms in the CAIs and break them into smaller pieces, stuff like helium and neon.
太阳形成后，迸发出质子一样的高能粒子。其中一些质子会撞击到钙铝混杂物上，让其分崩离析，分解成了细小颗粒、氦、氖。
And by studying those elements trapped in the rock, we can get a clearer picture of what the Sun was up to.
通过研究岩石里的这些元素，我们可以更加了解太阳在其中的作用。
But that still happens today, so just measuring helium and neon wasn't enough to learn something about the young Sun.
但这种现象今天依然在发生，所以仅仅通过氦和氖还不足以了解太阳初期的所作所为。
So instead, the team had to compare the CAIs to the rest of the meteorite, which was younger rock, to get an idea of what happened when.
所以，该小组必须要将钙铝混杂物与陨石的其他部分进行对比，陨石也是更为早期的陨石，这样才能了解当时发生了什么。
And once they did, they could confidently say that the Sun was much more actively releasing particles early in its life.
做了这些事情之后，就可以自信地说，太阳在刚刚形成后，曾大量释放颗粒。
This pretty much matches what those other methods have taught us about stellar evolution:
这就与我们通过其他方法得到的恒星演化过程相匹配了。
Young stars are active and belchy, then they bit more.
年轻的恒星很活跃，会不断吸食物体。
get older, maybe get a job, settle down a bit more.
随着年龄的增长，他们有了日常的活动领域，逐渐稳定下来。
But this is the first time we've seen direct evidence of that early activity using such ancient rocks.
但这是我们第一次看到有直接证据表明太阳初期活动的，而方法就是用古老的岩石。
And it gives us one more way of understanding how we all got here in the first place.
这也给了我们一种新方法，可以理解地球形成的过程。
It's a good thing the Sun settled down, though, because it makes life on Earth a whole lot easier.
好在太阳安定下来了，这样地球上的生命存活难度才不会那么高。
And hey, maybe it helped the Moon out once or twice, too.
或许太阳还帮过月球那么一两次呢。
Thanks for watching this episode of SciShow Space News!
感谢收看本期的《太空科学秀》！
If you would like to keep up with the latest research happening in astronomy and planetary science, you can go to youtube.com/scishowspace and subscribe.
如果大家想了解天文学以及行星科学领域的最新研究，可以订阅youtube.com/scishowspace哦。
