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Sometimes, it can be easy to forget that Mars has moons. Unless you are like me and you think about Mars all the time.
有时候，很多人很容易就会忘了火星也是有卫星的，除非像我一样时时关注着火星的人。
But it totally does. They are Phobos and Deimos, and they're a little mysterious.
话说回来，火星确实有卫星，火星的2个卫星分别是火卫一福博斯和火卫二戴摩斯，这两个卫星都颇为神秘。
They're so small that gravity can't pull them into spheres, so they're kind of lumpy and potato-shaped.
它们体型很小，火星的引力不足以将他们拉进磁场范围内，所以他们体型有点呈块状，像个土豆。
And scientists have spent decades trying to unravel where these tiny space potatoes came from.
几十年来，科学家一直在努力解开这两个卫星从何而来的谜题。
Now, a paper, published last week in the journal Science Advances, has gotten us one step closer to the full picture.
上周，期刊《科学进展》上发表了一篇论文，这篇论文让我们离问题的全貌有了更近一步的理解。
Its authors say that the popular origin story of a titanic, apocalyptic collision a few billion years ago isn't quite accurate.
这篇文章的作者指出，有一个广为人知的起源说法是：因为几十亿年前发生了一次大爆炸。但这个说法并不是十分准确。
Instead, there might've been just a mini-apocalypse. The surfaces of Phobos and Deimos look a lot like those of many asteroids.
相反，可能只是一次小爆炸，火卫一和火卫二的表面跟很多小行星十分相似。
And since the asteroid belt sits right outside Mars's orbit,
而由于小行星带恰好位于火星轨道的外面，
scientists thought for a long time that the Martian moons were asteroids that had been caught by the planet's gravity.
所以很长一段时间以来，科学家认为火星的卫星是受到火星引力作用的小行星。
But being gravitationally captured would've put huge stresses on both bodies.
但如果卫星受到引力的牵引作用，那么火星及其卫星都会受到巨大的压力作用。
Detailed studies of Phobos have shown that it, at least, would've probably broken apart under that much stress.
科学家对火卫一进行了细节研究，发现在这种巨大的压力作用下，火卫一会分崩离析的。
Plus, both moons also orbit more or less in line with Mars's equator,
此外，火卫一和火卫二环行时都与火星的赤道保持在一条线上，
which would be a big coincidence if they came from random directions like captured asteroids.
所以它们应该不是像小行星那样来自随意的方向，否则未免太过巧合了。
It would make perfect sense if they formed around Mars itself, though. That led to today's most popular idea: that, billions of years ago,
它们要是在火星附近形成的，就说得通了，基于此，有了今天的一个知名的想法，那就是数十亿年前，
Mars collided with a protoplanet, a huge, rocky precursor to the stuff in today's solar system.
火星与某个原行星发生了撞击。这颗原行星是今天火星的前体，它是体型庞大的石制星体。
That collision launched lots of rock into space, and some of it eventually became Mars's moons.
这次撞击使太空中多了许多岩石，其中部分岩石最终变成了火星的卫星。
That's pretty much how our moon formed, so there's some precedent for this. There's also lots of evidence on Mars itself for a gigantic collision.
月球也是大概是这样形成的，都是有某种前体的，还有大量证据表明火星本身确实发生过大爆炸。
Like, almost all of the northern hemisphere is at a lower elevation than the southern one, which could be explained by a huge impact.
比如，几乎所有北半球的海拔都要比南半球低，而大爆炸产生的影响就可以解释这个现象。
But this new paper says there's a problem with these ideas, too.
但这篇新发表的文章中指出，这些想法也是存在问题的。
Based on earlier calculations and simulations, scientists had settled on an impactor that was about a third Mars's size and about two percent its mass.
基于此前的计算和模拟，科学家找到了一种撞击器的身上。这种撞击器的大小是火星的1/3，质量是火星的2%。
But these authors simulated possible collisions in more detail than ever before.
但这篇文章的几位作者模拟了几种可能的撞击情况，比以往的研究都要更加细化。
And their work showed that such a big impactor would've launched way too much rock into space.
他们的研究表明，这个大型的撞击器导致宇宙中多了许多岩石。
It would've formed long-lasting moons that look a lot different from Phobos and Deimos.
撞击器形成了可以长期运转的卫星，样子与火卫一和火卫二大不相同。
They found that, to get the right conditions for the current moons, you'd need to hit Mars with something between ten and a hundred times lighter.
他们发现，要确认形成当前卫星的合适条件，就需要用质量为其1/10到1/100之间的物体来撞击火星。
So far, this is the best model we have of how these moons formed, but the debate isn't over yet.
目前为止，关于火星卫星的形成方式，这是最好的模型了，虽然讨论依然在继续。
In 2029, it and the other impact models will be tested once and for all when the Japanese MMX mission brings a piece of Phobos to Earth.
2029年，会对这个模型以及其他所有的碰撞模型进行唯一的一次测试，因为那时候日本的火卫探索任务(MMX)会将火卫二的部分材质带回地球。
A huge impact would've dried out the rocks escaping from Mars, so the sample would still be dry today if that's how they formed.
大碰撞会使从火星而来的岩石消陨，所以这个模型即便是正确的，时至今日样本也会是干的。
But if the moons started as asteroids, they wouldn't have been baked as effectively, so the sample would be a lot wetter.
但如果火星的卫星一开始就是小行星的话，就不会干的那么快，那么样本就不会那么干。
We're just going to have to wait and see. Meanwhile, twelve and a half billion years ago, there was no Mars what a sad universe that was.
我们就等到2029年看看吧，125亿年前，宇宙里是没有火星的，那时候是多么的无趣啊。
But according to a paper published in this week's issue of Nature, there was a small group of galaxies called SPT2349-56.
不过，本周《自然》期刊上发表的一篇论文称，有一个名为SPT2349-56的小星系群。
I think that's what they called it back then at least. Well that might be the most active region of space we've ever seen.
至少那时候是这样叫它的，这个区域可能是我们目前所知的最为活跃的区域了。
This group, which we'll call 2349 for short, was discovered using the South Pole Telescope.
这个星系群，就简称为2349吧，是我们用南极望远镜发现的。
Shockingly, this is a telescope near the South Pole, where the atmosphere is clearer than almost anywhere on Earth.
令人震惊的是，南极望远镜位于南极附近，因为那里的观测环境要比地球上的其他地方都更清楚。
It's thanks to those near-perfect conditions that the team found 2349, although they did examine it with a bunch of other telescopes later.
多亏了南极的绝好环境，该研究小组才得以发现了2349，虽然此后他们确实也用其他一些望远镜进行了观测。
Based on how light changes as it travels through space,
基于光在宇宙间穿梭时改变速度的方式，
the team estimates that we're seeing this object as it was just 1.4 billion years after the Big Bang, when the universe was about a tenth its current age.
该研究小组估测，我们之所以能看见它，是因为它是在宇宙大爆炸仅14亿年后产生的，那时候宇宙只有现在年龄的近1/10。
That's only a few hundred million years after the very first galaxies formed,
第一批星系形成后的几亿年后，2349就形成了，
so there weren't the kinds of gigantic clusters of hundreds or thousands of galaxies we see today.
所以那时候还没有形成我们今天看到的无数的大型星系群。
Instead, 2349 is officially what's called a protocluster: an early seed of today's much larger groups.
相反，2349被称为原星团，也就是今天更大的星系群的前体。
Objects like this tell astronomers that galaxies clumped together from the very beginning,
2349这样的存在让天文学家知道：星系从一开始就是聚集在一起的，
and that there wasn't a big gap between the first galaxies and the first groups of them.
而且第一批星系与第一批星系群之间的差别不是很大。
2349 is pretty dense for a protocluster, only about 425,000 light-years across but it's really busy in there.
2349是原星团里密度较大的了，维度大概只有42.5万光年，但那里的活动却非常频繁。
It contains at least fourteen galaxies, and they're all forming new stars somewhere between fifty and a thousand times faster than the modern Milky Way.
其中包含至少14个星系，而且2349形成恒星的速度是现代银河系的50倍-1000倍。
Combining all these stats with models for protocluster evolution,
在结合了这些数据以及原星团演变的模型之后，
the paper's authors think 2349 eventually formed one of the largest clusters in the modern universe.
本文作者认为，2349最终形成了现代宇宙里最大的星团之一。
Of course, we can't really know what it looks like today, because the idea of today doesn't really work in astronomy.
当然了，我们并不是很清楚2349今天的样子，因为今天这个概念是不适用于天文学的。
The light from its earliest stages is just reaching us, so we'll have to wait for like billions of years for the light from later stages to get here.
2349初期发出的光刚刚抵达地球，所以我们还要等几十亿年才能接收到2349后来发出的光。
For now, all we can say is that it's one of the densest and brightest protoclusters we've ever seen.
目前为止，我们能下定论的就是：2349是我们见过的密度最高、亮度最大的原星团。
And there are some signs that it's even bigger, too.
也有一些迹象表明，它的体积越来越大了。
There are five additional galaxies that might also be part of this group, although the paper's authors couldn't quite tell.
还有5个星系可能是这个群体的一部分，虽然本文作者并未详细陈述。
But if they are, it would make this the most active region of space that scientists have ever discovered.
但如果这5个星系真的是该群体的一部分，那么这个区域就是科学家迄今为止发现的最为活跃的区域了。
Still, the universe is big, and there are a lot of places to look.
当然了，宇宙很大，我们还要多看看。
So we'll keep you posted if anyone finds something that breaks the record. Thanks for watching this episode of SciShow Space!
如果有破纪录的其他发现，我们会及时更新的，感谢收看本期的《太空科学秀》！
If you would like to stay in the loop about the latest news from all over the universe, you can go to youtube.com/scishowspace to subscribe.
如果您想要了解有关宇宙的最新消息，可以登录并订阅youtube.com/scishowspace。
And heck, why wouldn't you?
不订阅可是自己的损失哦！
