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Thanks to Brilliant.org for supporting SciShow Space.
节目开始，先要感谢《太空科学秀》的赞助商Brilliant.org。
The Milky Way is our home, so you'd think we'd know a lot about it.
我们在银河系里生活，所以大家会以为我们对银河系已经了解很多了。
And we do. But a whole galaxy is a pretty big place, so there's still plenty of weird stuff that we're trying to figure out.
确实如此，不过整个银河系很大，还有很多奇怪的谜题有待解开。
And that's the cool stuff! So, here are three questions scientists are still trying to puzzel out.
这是最酷的部分了！这里向大家介绍3个科学家仍在努力解开的谜题。
One is our galaxy's shape. We know that we live in a spiral galaxy, with long, sweeping arms packed with stars.
第一个就是银河系的形状，我们都知道，银河系是螺旋形的星系，它的旋臂很长，覆盖面很广，里面布满了恒星。
But why's it like that? After all, stars form from a fog of gas and dust called the interstellar medium, or ISM.
但为什么会这样呢？毕竟，恒星是由气体和灰尘组合成的雾团形成的，这种雾团又称星际介质。
And the ISM is everywhere within the galaxy, so why do stars congregate in the arms?
银河系里到处都是星际介质，那么恒星为何会聚集在旋臂中呢？
Well, we don't totally know, but we're making progress.
这个，我们也不是十分清楚，但正在逐步拨云见雾。
One clue comes from structures called filaments that astronomers in the 1980s started to find at the cores of some galactic arms.
其中一个线索来自一种丝状的结构，这是上世纪80年代天文学家在银河系的一些旋臂核心处发现的。
Filaments are dense regions of the ISM that are incredibly thin, up to a hundred times longer than they are wide.
这种丝状结构是星际介质中密度较高、厚度很薄的区域，其长度是宽度的100倍。
They can stretch for hundreds of light-years but, weirdly, seem to exist on all size scales, kind of like a fractal.
这种结构可以达到数百光年长，但很奇怪的是，似乎其大小跨度很大，有点像不规则的碎片形。
Together, they form a sort of galactic skeleton for the Milky Way, providing ingredient-rich places for new stars to form.
这些结构聚集在一起，就可以形成银河系的骨骼，为新恒星形成提供原料丰富的环境条件。
The European Space Agency's Herschel Space Observatory has even found filaments connecting all the closest star forming regions!
欧洲太空总署的赫歇尔空间天文台甚至发现，这些丝状结构可以连接起距离相近的恒星，形成一片恒星区域。
But exactly how many of these structures there are and how they play a role around here is still up for debate.
但至于银河系里有多少这种丝状机构，以及这些丝状结构在这里发挥了怎样的作用还有待发掘。
That's not the only mystery our galaxy's stars present.
这不是银河系恒星存在的唯一一个谜题。
As astronomers have mapped out the positions and speeds of nearby stars more accurately, they've found they're less predictable than expected.
随着天文学家越来越精确地勾画出附近恒星的位置和速度，他们发现，恒星比我们想象地更捉摸不定。
Instead of mostly circling in a flat plane,
大多数恒星并非绕平面转圈，
a research group discovered in 2012 that many stars seem to be moving up or down about 10% as fast as they're circling the galactic center.
因为2012年某研究小组发现，很多恒星移动的速度会在它们围绕银河系中心速度的基础上上下浮动10%。
When mapped out at large scale, the Milky Way's stars even seem to be rippling with waves.
当我们大规模勾勒出银河系模样的时候发现，银河系里的恒星似乎都泛着波。
Studying these waves is called galactoseismology and, like the study of seismic waves here on Earth, it may reveal clues about unseen events.
对这些波的研究又称银河地震学，而就像地球上对地震波的研究一样，银河地震学也会揭示出一些我们看不到的事件的蛛丝马迹。
The waves are probably the result of a big collision with the Milky Way but where's the collider?
这些波可能是银河系某次大型碰撞的结果，但相撞的对象是谁呢？
Researchers aren't sure, but they think there are two likely possibilities, both of which would've happened about 100 million years ago.
研究人员还不确定是谁，但他们认为有两种可能性最大，这两种情况大概都发生在1亿年前。
One's kind of standard: an interaction between our galaxy and one of its many satellite galaxies.
一种是较为常规的情况：银河系和自己众多卫星星系中的一个发生了碰撞。
The other, though, is really cool: It's possible that the Milky Way collided with a massive dark matter structure, and its gravity stirred up all those stars.
另一种情况就不是很常见了，但也有这种可能，那就是：银河系跟某个巨大的暗物质结构相撞，而引力作用扰乱了所有恒星。
Although we can't see dark matter, we know it's all around us, especially near our galaxy's outer edges.
虽然暗物质是看不见的，但我们知道它们无处不在，尤其是在银河系外缘附近。
But just because we can't find the culprit, doesn't mean it's gotta be dark matter.
但我们虽然找不到罪魁祸首，但这并不意味着就一定是暗物质造成的。
Whatever the collision was, its trajectory probably carried the other object to a place beyond the galactic core and basically out of sight from Earth.
无论发生怎样的撞击，其轨迹都很有可能将另一个物体带往一个银心之外的地方，一个地球上看不到的地方。
There's also at least one piece of evidence suggesting a dwarf galaxy might've been the culprit instead.
至少有一则证据表明，某个矮星系是罪魁祸首。
Astronomers have found a few stars traveling so fast that they couldn't have come from our galaxy,
天文学家发现了一些恒星，他们速度极快，不可能来自银河系，
so they might have been knocked loose during that big collision.
所以它们可能是在某次大型撞击中被击散的。
Either way, we'll have to work fast to figure this out because those waves of stars will probably disappear in another hundred million years.
无论是哪种情况，我们都必须快速行动起来搞清楚这一点，因为恒星产生的这些波很可能在1亿年后消失。
Then again, maybe we won't have to work that fast after all. Finally, stars aren't the only thing traveling weirdly fast around here.
不过，我们或许也不必操之过急，毕竟最后，以奇异方式移动的东西并不只有恒星。
For decades, astronomers have observed a few clouds of gas moving at strangely high velocities,
几十年来，天文学家观测到了一些气体云，他们移速极高90km/s，
up to 90 kilometers per second faster than the stuff around them.
比周围物体的移速都要快。
At that speed, it would take only a year and a half to travel from the Sun out to Neptune!
以这个速度，只需一年半就能从太阳飞向海王星。
Always on the lookout for a clever name, researchers call them high-velocity clouds.
研究人员一直在想给它们起什么名字，目前暂定为高速云。
These clouds are mostly found in the outer, halo region of the Milky Way,
高速云几乎都是在银河系外缘的光晕处发现的，
and they're often observed to have a low metallicity, or abundance of heavier elements.
而且通常在其中很少发现金属或比金属更重的成分。
And they're not small, either: They can contain millions of times more material than the Sun and span tens of thousands of light-years.
而且它们形态也不小：其中包含的物质是太阳的数百万倍，跨度达上万光年。
Scientists have four main ideas about where they might have come from: The oldest hypothesis, proposed by famous astronomer Jan Oort,
对于它们的来源，科学家有4种主要的猜测：最开始的假设是由著名天文学家扬·奥尔特提出的，
suggests that the clouds might be the far-flung leftovers of the process that formed the Milky Way.
这种假设认为，这些高速云可能是银河系形成过程中残留的以极速甩出的残留物。
With only the weakest gravitational pull affecting them, that far-off material would've taken billions of years to get here, speeding up along the way.
由于引力微弱，几乎影响不到他们，所以这些高速云花了数十亿时间才抵达这里，前进途中一直都在加速。
Another idea is that because they do have such low metallicity,
另一种假设，高速云的金属含量很低，
high velocity clouds are the remnants of an ancient collision between the Milky Way and another galaxy.
所以他们是银河系和另一个星系在古时候相撞后的残留物。
Hey, where have we heard that before? A related hypothesis is that the material is made up of gas stolen gravitationally from a satellite galaxy.
咦？这假设听起来咋那么熟呢？还有一个与此相关的假设认为，高速云是由气体形成的，而形成它的气体是受到了引力作用从另一个卫星星系中过来的。
That seems especially likely for the clouds found in the southern hemisphere,
这听起来倒挺有可能的，因为这些高速云是在南半球发现的，
which is in the direction of the Magellanic Clouds, our closest galactic neighbors.
就在离我们最近的麦哲伦云的方向。
One last idea is that these clouds actually came from the Milky Way all along.
第四种假设认为，这些高速云就是来自于银河系。
Perhaps a powerful supernova explosion hurled them away from the galaxy's disk, only for gravity to claw them back before they could fully escape.
或许，一次威力巨大的超新星爆炸，导致星系盘中甩出了高速云。全靠引力作用，高速云才没有完全逃逸出银河系。
There's even a chance different clouds could have different origin stories.
甚至有可能不同的高速云有不同的来源。
To figure that out, astronomers are studying the composition of each cloud in detail.
要弄清楚这一点，天文学家正在细致地研究每个高速云的组成。
If they were created in different ways, there might be a signature of their home still waiting to be detected.
如果他们能以不同方式产生的话，他们的起源地可能还会发出信号，等待我们的探寻。
We'll just have to wait for the results. We don't yet know the answers to any of these Milky Way mysteries or many others out there.
我们现在只能耐心等结果了，对于银河系的许多奥秘，我们还没有答案。
But put them all together and our galaxy suddenly seems a lot less isolated and our cosmic neighborhood a lot busier.
但将它们放在一起的时候，银河系之间的物体突然就显得没那么相互孤立了，其他星系也显得繁忙了许多。
Just watch out for any flying galaxies. One place within the milky way where we can figure out the answers to big questions relatively quickly is Brilliant.org.
我们就寻找其他运行的星系吧，银河系里有一个地方，我们能在那里快速找到很多疑团的答案，这个地方就是Brilliant.org。
Inspired by these existing questions about the milky way, I'm working on the Dark Matter quiz.
受到银河系里现有问题的启发，我们正在出暗物质的小测验。
Leading up to it was a lesson and quiz on the fate of the universe that I looked through to prep, but this starts off pretty easy.
在那之前，大家可以观看与宇宙发展有关的一节课，并做一下测验，很容易上手哦！
So this question wants to know what is the dominant source of mass in our solar system.
要回答这个问题，就要知道太阳系里的主要物质来源是什么。
So the Sun! So I got it right and so did 72% of the other people in the Brilliant community.
当然是太阳啊！这道题我答对了，这道题的正确率是72%。
Which is a neat thing about Brilliant because you can see how you did but also see how other people did when they answered the question.
Brilliant上面显示很清晰，大家不仅知道自己做的怎样，也可以看到其他人的答题情况。
I think what sets Brilliant apart from other education sites is this community aspect.
我觉得Brilliant的与众不同之处就在于这样的用户效应。
On Brilliant you can answer questions that other people have submitted or you can even submit your own questions to be answered.
在Brilliant上，大家也可以回答别人提出的问题，或者提交自己的问题等待他人回答。
So check it out for yourself and let us know if you submit a question and I'll try to solve it.
心动不如行动，如果提交了问题的话，可以告诉我们一声哦，我会试着帮大家解答的。
And the first 777 people to use that url to sign up for an annual premium subscription will get 20% off.
前777位登录Brilliant并订阅整年的用户可以得到20%的费用减免哦！
Plus, you'll be helping to support SciShow Space when you do, so thank you!
此外，也是对《太空科学秀》栏目的支持，谢谢大家！
