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This episode is supported by NordVPN.
本期节目由NordVPN赞助播出。
Go to nordVPN.com/SPACE to learn more about virtual private networks, and internet security.
大家可以在nordVPN.com/SPACE上了解到更多有关虚拟专用网（VPN）和互联网安全的知识。
For as long as you and I have been alive, in fact, for as long as humans have been looking at the sky, the planets have seemed more or less like a merry-go-round, reliably repeating the same orbits over and over.
在你我有生之年，乃至全人类尚未灭绝期间，所有行星多少都像是旋转木马一样，一遍又一遍地沿着既定轨道运行。
But now that we've found hundreds of systems with multiple planets, there's reason to believe that solar systems are much more dynamic than we might have expected.
但现在，鉴于我们已经发现了含有多颗行星的上百个星系，我们就有理由相信，太阳系比我们曾经认为的动态性更强。
Planets appear in orbits where they couldn't possibly have formed, and starless rogue planets float through space, many of them apparently ejected from their solar systems.
许多行星出现在他们本不可能形成的轨道上，而没有恒星可以环绕的行星就在太空里流浪，很多这样的行星显然都是从太阳系里喷射出来的。
Yet, among all this volatility, there are islands of stability.
不过，虽然有这样的不稳定性，但也有相当稳定的地方。
Everywhere we look, we see groups of planets and other satellites that sync up their orbits and find safety by orbiting in gravitational lockstep.
环视宇宙，可以看到许多行星群和卫星会将轨道同步，并在引力的作用下找到安全的方式运行。
They can stably survive much of the turbulence of solar systems.
太阳系的大部分不稳定情况，它们都能挺得过去。
Yet, their entire existence is like a fossil record of much more volatile times in the distant past.
不过，它们的存在可以表明很久以前不稳定时期的情况，犹如化石一般记录着。
It's one of the best ways we have of learning what happens during the birth of a solar system.
这是我们了解太阳系诞生期间所发生情况的最佳方式之一。
Now, you might find it strange to think of a solar system as volatile in the first place.
在第一次听到太阳系不稳定的说法时，大家可能感到奇怪。
But planets and other objects around a star are constantly getting tugged around by anything with gravity.
但无论是行星还是恒星附近的其他物体都始终会受到任何引力作用的拉扯。
So, no planet's trip around a star is exactly like the one before it.
所以，以前行星围绕恒星运行的方式与现在不同。
And even small nudges can add up in unpredictable ways.
即便是小的“推搡”也会产生不可预料的后果，
They can whisk a planet out of its orbit or send it into collisions, near misses, or some other gory end.
会导致行星脱离轨道、相撞甚至出什么其他差错。
But throughout our galaxy, all sorts of objects have found relative safety by locking into a formation called orbital resonance.
但太阳系里的所有物体都是相对安全的，因为它们是按照轨道共振的方式来运行的。
When two objects are in resonance, it means that their orbits are a ratio of two whole numbers.
2个物体能发生共振，就表明它们的轨道有2个整数的比例。
For example, maybe the first object completes two orbits every time the second object completes three.
比如，或许第一个物体每次完成2个轨道的时候，第二个物体都完成了3个。
When they lock into this formation, their gravitational influence on each other holds them in a stable orbit.
它们一旦形成这种固定的模式，彼此间的引力作用就会让它们形成一个稳定的轨道。
It can keep them from migrating further or getting shaken up by other passing objects.
这样，就不会进一步偏离，或者因为有物体经过而分解。
It can also keep planets from getting too close and colliding.
还能防止行星之间因为距离过近而相撞。
In fact, that's probably why we still have Pluto.
实际上，这很有可能是冥王星依然存在的原因。
Pluto and Neptune's orbits cross paths but they never collide because they're in resonance;
冥王星和海王星的轨道有交错之处，但它们从未相撞，因为他们有这种共振的和谐。
Pluto makes two orbits every time Neptune makes three.
冥王星每次产生2个轨道的时候，海王星都会产生3个轨道。
These bodies, bound to each other by gravity, can act kind of like a celestial gang that keeps each other safe.
这两个星体是通过引力作用捆绑在一起的，就像结成了帮派，互彼此周全。
But resonances can only form in systems that are dynamic to begin with, meaning they're not just merry-go-rounds, endlessly repeating the same loops;
但这种共振只能在初期动态的系统中形成，也就是说：它们并不是旋转木马那么简单，不是在简单重复着运行。
they're systems where planets are actually migrating toward each other, something that often happens early in a solar system's life.
它们的系统中，所有行星都在朝彼此运动，太阳系生命产生初期，这种现象时有发生。
While a planet drifts, it may wander close to another object, which gives it a pull every time it reaches a certain point in the orbit.
一颗行星发生偏移的时候，会离另一个物体很近，这样它每次抵达轨道某个点的时候，就会受到引力。
It's like when you're pushing a kid on a swing.
就像推一个小孩子荡秋千一样。
If you give it a push every time the swing gets to the top of its arc, the kid will go higher and higher.
在达到弧形顶点的时候，如果给孩子一个推力，孩子就会达到更高的地方。
That's because you're reinforcing the frequency of the swing.
这是因为秋千的频率因为这个推力而增大。
And a similar thing happens to these two orbiting objects.
这两个环行物体还会发生类似的情况。
If the first object keeps getting a tug that lines up with the frequency of its orbit, it gets stuck in that frequency.
如果第一个物体一直受到与轨道频率相同的拉力，它就会保持这样的频率。
And the two objects keep going around the central star or planet, pulling periodically on each other in a way that reinforces their pace around the sun.
这两个星体会一直围绕中央的恒星或者行星运转，周期性的给彼此以拉力，不断加快它们围绕太阳运转的频率。
Once objects are trapped in these resonant orbits, they're much harder to disturb.
一旦物体陷入轨道的这种共振，就很难脱离出来。
Now, resonance is not always a good thing if you're worried about stability.
共振其实并不利于稳定。
For instance, in places such as planets' rings, objects can be destabilized when different resonant systems overlap.
比如，在行星星环这样的地方，物体会因不同共振系统的交叠而失去稳定。
In spite of its two-faced role, resonance seems to be a really important part of the story of how solar systems form.
虽然它处于2个系统中，但共振似乎对太阳系的形成方式有重要作用。
In our own solar system, many moon and ring systems are full of resonances.
在太阳系中，很多行星和星环系统里都是各种共振。
Jupiter's moons Io, Europa, and Ganymede are all in resonance.
木卫一、木卫二、木卫三都处于这种共振之中。
The gaps and dense spots in Saturn's rings all formed from resonances, too.
土星星环中的空隙点和高密度点也是由共振形成的。
And in extrasolar systems, around a third of observed exoplanets seem to be in orbital resonance, or at least close to it.
在太阳系以外的星系中，我们观测到近1/3的系外行星似乎都有轨道共振的情况，或者即将进入这种共振。
One of the most important things this tells us is that solar systems are not static places.
这一点对我们最大的提示就是：太阳系并非静态的。
In general, planets and other objects don't just form in one place and stay in that orbit forever.
总体来说，行星等物体不会只在一个地方形成，也不会一直保持在所形成的轨道里。
Many of them migrate, and as they do, they get captured in resonances and get stuck in those orbits.
很多星体都会发生迁移，在迁移的时候就会不小心进入某种共振，并锁定在相应的轨道里。
Ironically, these resonances, these little islands of stability throughout the universe, are a memory of a past full of movement and change.
好处是：这些共振是宇宙里具有相对稳定性的小岛，它们记录着迁移和改变的过去。
Next, scientists are working on figuring out why we don't actually see more resonances in a majority of systems.
接下来，科学家会着手弄清楚无法在大多数系统中看到更多共振的原因。
Maybe the answer is that some systems don't have a lot of migration, or maybe something happens to break up these resonances.
或许答案是：很多体系不会发生大量迁移，也可能是发生了什么导致这种共振被破坏。
Either way, it'll tell us something new about how solar systems form.
无论是哪种情况，都让我们对太阳系的形成方式有新的了解。
And since we can't look directly at any solar system's past, including our own, he fossil record in these resonant systems is one of the best ways we have to understand where we come from.
由于我们无法直接观测到太阳系的过去，甚至连地球的过去，我们也无法观测。因此，这些共振系统留下的化石是了解我们来源最好的方式之一。
One way to ensure stability a little closer to home is to protect yourself from people trying to steal your private information.
确保离家近的这种稳定性有一个方法：保护个人信息不被窃取。
NordVPN is a service that encrypts the data you send and receive online.
NordVPN的服务可以对发送和接收的数据进行编码。
Your internet connection is kept totally secure, NordVPN's Chrome browser is lightweight and user-friendly from the first click.
NordVPN可以确保互联网连接绝对安全，它的Chrome浏览器占用空间很小，而且上手简便。
It secures your browsing in seconds. And the Android and iOS apps can even secure your browsing while you're using those mobile devices.
它可以在几秒内实现连接。安卓和苹果上都可以下载这款应用程序，所以用手机也能实现浏览。
There are thousands of super-fast servers in 61 countries, and they're always adding more.
61个国家有上千个速度极快的服务器，而且数量还在不断增加。
For a limited time get 75% off a 3-year plan at nordvpn.com/SPACE.
现在限时3年75折优惠，详情请戳nordvpn.com/SPACE。
This special offer makes your subscription just $2.99 per month so you can browse and shop securely online, on all your devices.
优惠期间，月费是2.99美元，这样无论用什么设备上网，都安全无误。
And for a short time, use code SPACE to get an extra month of Nord for free!
最近可以用优惠吗SPACE来享受首月免费！
Check out the link in the video description to learn more.
可戳刚才的网址来了解更多哦。
