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Compared to a human lifetime, timescales in space are enormous.
与人类的一生相比，宇宙的时间尺度可以说是非常之大了。
So it's easy to imagine that our Galaxy is basically frozen during the handful of decades that we're alive.
所以，可以简单这样理解：人类短短数载的时间里，银河系就如同静止了一样。
After all, generations and generations of our ancestors have looked at the same planets and constellations that we see today.
毕竟，人类的历代祖先跟我们看到的同一片天空，天空里的星星和星座也都是一样的。
But, that being said, galaxies are really dynamic, and the Milky Way is changing all the time.
不过，虽然如此，有些信息动态性十分强，比如银河系就在时刻变化。
In fact, in your lifetime, let's call it a hundred years, it will undergo some pretty amazing changes.
实际上，在人类的一生中——姑且称之为100年吧，人类会发生许多奇妙的变化。
For one, it will probably grow, like, a lot.
一方面，人类很有可能会长大，是长大很多的那种。
According to a 2018 paper, spiral galaxies like ours are steadily expanding at around 500 meters per second.
2018年的一篇论文指出，像银河系这样的涡旋星系正在稳步以大约500m/s的速度膨胀。
That's roughly twice the speed of a jet!
这个速度可是喷气式飞机的两倍哦！
And if this rate also applies to the Milky Way, that means it will grow about one point five billion kilometers over the next century.
如果银河系也是以这个速度膨胀的话，那么也就意味着银河系在未来一个世纪中会膨胀大约15亿公里的样子。
That's not just a statistic, either.
这样不只是数据而已。
This number can also teach scientists about galactic evolution in general.
这个数字也让许多科学家知道了银河系演化的整体情况。
See, the fact that these galaxies grow wasn't a total surprise.
让科学家知道涡旋星系的膨胀并不令人惊奇。
For years, scientists have known that, every once in a while, they can eat up smaller galaxies that get captured by their gravity.
过去这些年来，科学家已经知道了一件事——涡旋星系会时不时地吞并一些受到自己引力作用的小星系。
But that 2018 paper was important because it confirmed that this isn't the only way these neighborhoods get bigger.
但那篇2018年发表的论文十分重要，原因在于这篇论文证实了这并非这些涡旋星系变大的唯一方式。
They also expand because new stars are being born, and in a pretty odd place, too.
涡旋星系会膨胀还有一个原因：新恒星在奇怪的地方产生了。
In this study, researchers observed two spiral galaxies like ours.
在这篇论文中，科学家观测了2个与银河系类似的螺旋星系。
And after calculating how stars on the fringes were moving, they concluded that these galaxies were growing because stars were being born on their edges.
他们先是计算了边际恒星的移动方式，然后下了一个结论——这些星系之所以会膨胀是因为有一些恒星在边际处诞生了。
Models had predicted this, but it was hard to prove they were right just by looking at the Milky Way since, well, we're inside it.
有一些模型已经预测到了这件事，但仅凭观测人类所在的银河系本身是很难证明这一点的。
So by looking at other galaxies, scientists were able to confirm their hypothesis.
所以，通过观测其他星系，科学家就可以证实他们的假设。
This finding was mainly strange because most stars form toward the center of their galaxy.
这则发现的主要奇怪之处在于：大多数恒星倾向于在其所在星系的中心形成。
So this paper demonstrated that there can still activity way out in the galactic outskirts.
而这篇论文证明恒星可以在星系的边际处发生活动。
That means that, even if it never interacts with another galaxy, the Milky Way will likely keep growing while you're alive, as long as it has enough gas around the edges to make new stars.
这就意味着：即便银河系从来不跟其他星系有互动，但银河系在人类存续期间可能会一只膨胀，只要满足了前提条件——边际处有足够的气体，可以形成新的恒星。
Of course, at this point in its life, our Galaxy is making stars pretty slowly, churning out maybe one or two a year.
当然了，在当前的时期，我们的银河系产生恒星的速度是非常之慢的，大概一年只会产生一两颗恒星。
But that means that in the course of your lifetime, it could gain around a hundred new stars!
但这意味着：在一个人的一生中，银河系可以产生100颗新的恒星哦！
Now, sure, for a place with at least a hundred billion stars, that's barely a sprinkling.
不过，当然了，对于一个已经有1000亿年历史的星系来说，这个数据量太小了。
Things have slowed down now that our Galaxy is well into adulthood, at a healthy thirteen and a half billion years old.
银河系活动的频率已经随着它进入成年期而减慢，毕竟银河系已经有135亿年的历史了。
It's a long ways from its wild youth, about nine billion years ago, when it was forming around a dozen stars a year.
大概90亿年前，银河系正处于青少年时期，那时候，每年能产出几十颗恒星。
Still, from a human perspective, a hundred new stars is nothing to scoff at.
不过，从人类的角度看，100颗新恒星真的很棒了！
And besides, understanding that number can also teach scientists how the Galaxy has evolved.
况且，这个数据也让科学家知道了银河系演化的方式。
Because the thing is, the Milky Way's star formation hasn't just tapered off, it's been more of a rollercoaster.
因为重要的是：银河系的恒星还是在不断变多，就像滚雪球一样。
After that peak around nine billion years ago, star formation dropped to a tenth of its previous rate.
90亿年前是银河系产出恒星的高峰时期，现在的产出速率已经降至90亿年前的1/10了。
This shutdown happened around the same time that our Galaxy formed its thick disk.
而且当前也是银河系形成厚厚星系盘的时候。
Scientists aren't exactly sure how the two events are connected, but they think it's possible that the formation of this disk stirred things up and made the gas so hot that it stopped condensing into stars.
科学家不是很确定这两件事之间的联系，但他们认为有可能星系盘的形成扰乱了银河系的节奏，导致气体温度升高，无法凝聚成恒星。
Fortunately, star formation has picked up again since then although these days, things are pretty quiet.
所幸，恒星又开始慢慢形成了，只不过最近的形成速率很低。
Still, that's relatively normal for older neighborhoods, like ours, that don't have a lot of interaction with other galaxies.
不过，话说回来，像银河系这样内向的老星系，活动不频繁也是正常的。
Even so, the Milky Way is popping out the occasional new star, as regions of dust condense and ignite.
即便如此，银河系还是会时不时地爆出新恒星，因为系内的气体会凝聚后迸发。
And over the course of a century, our Galaxy is likely to have dozens of new studs of light.
在过去的一个世纪中，我们的星系很有可能已经出现过一些超新星了。
Finally, the Milky Way won't just gain things during your lifetime. It will also lose some.
最后想说的是：银河系在人类的一生中不只会吸收事物，也会流失事物。
After all, the Milky Way's new stars are just the recycled remains of old ones, and in the next hundred years, it will likely lose about as many stars as it gets.
毕竟银河系的新恒星身上有旧恒星留下的物质，在未来100年间，银河系很有可能会失去曾经吸收的物质。
Two or three might even explode as supernovas.
其中有那么两三个还会在超新星时期爆炸。
This will only happen to the really massive stars, but when they die, they'll spew their contents into space, and some of the elements from their cores will be incorporated into new stars.
这种情况只会在特大质量恒星的身上发生，不过，在恒星消亡时，会将身上的物质甩向太空中，其内核的一些元素会组合成新的恒星。
As far as we know, the most recent supernova in our Galaxy blew up around 140 years ago.
就我们目前了解的情况：银河系最近产生超新星是在大约140年前。
But a 2006 estimate suggests that, on average, the Milky Way has seen a supernova explode around every 50 years.
不过，2006年的一项估测显示，平均来看，银河系大概每隔50年就会出现一次超新星。
So in a sense, it seems like we're kind of overdue for some fireworks.
所以，从某种程度来说，有些超新星，我们会错过。
And scientists may have found the next culprit.
科学家可能已经发现了下一个犯人。
They have their eyes on a triple-star system nicknamed Apep,
他们将目标转移到了一个名叫阿佩普的三恒星的体系。
which is about eight thousand light-years away and seems to be on the brink of explosion at least, based on what we can see of it.
阿佩普距离我们大约有8000光年远，而且根据我们的观察，它就快进入超新星时期了。
One of its stars is releasing streams of charged particles at a speed that suggests it's at the point of collapse.
其中的一颗恒星已经开始释放带电粒子流，释放的速度给人的感觉是快进入超新星时期了。
Thankfully, because of the way the star is oriented, it shouldn't do any harm to Earth even if we see evidence of that explosion soon.
谢天谢地的是：从这颗恒星的朝向来看，对地球不会有什么伤害，虽然就快发生爆炸了。
And either way, cosmic “brinks” can be human lifetimes, so it's hard to say exactly when this thing will go.
不过，无论是哪种情况，宇宙的“边缘”可能都会威胁人类的生命，所以很难确定事情的走向。
We might not see evidence of its explosion for another thousand years or more.
未来1000年左右的时间里，我们可能不会发现其爆炸的证据了。
Whether or not the Galaxy lights up with a new supernova in the near future, the Milky Way is far from the frozen river of stars that you see on a dark night.
无论该星系在不远的未来是否会出现新的超新星现象，银河系距离我们在夜空中看到的一长串恒星是很远的。
In your lifetime alone, dozens of stars will blink in and out of existence, and the whole Galaxy will likely push its own boundaries by more than a billion kilometers.
在大家的一生中，有数十颗恒星会出现又消失，而整个银河系很有可能会在你一生的时间里膨胀10万多公里。
And it's not just cool to find events in space on the scale of our lives.
以人的一生为参考来发现太空中的活动是很有趣的事情。
Understanding these short-term events also helps us get a handle on how galaxies evolve and sort out what it's like to be in the galactic middle age.
对这些短期活动的了解也会帮助我们获取信息，了解各个星系是如何演化的，同时也能了解一个星系处于中年时期的样子。
Thanks for watching this episode of SciShow Space!
感谢收看本期的《太空科学秀》！
The universe is super fascinating and can also be surprisingly accessible, and we love getting to explore it with you.
宇宙是非常奇妙的，也不是完全无法了解，我们愿意与大家一起探索宇宙的奥秘。
If you want to support the show and help us keep making more free content like this, you can go to patreon.com/scishow.
如果您想支持我们的节目并帮助我们制作更多类似本期视频的话，可以访问patreon.com/scishow。
