(单词翻译:单击)
By now, planets around other stars are old news.
其他恒星附近也有行星存在这件事，已经不是新鲜事儿了。
In the last couple of decades, astronomers have found thousands of these exoplanets, and now, it's time to start learning more about them.
过去几十年来，天文学家发现了很多系外行星。现在是时候对他们了解更多些了。
And one of the things researchers are looking for are rings.
天文学家一直都在搜寻的东西是行星环。
After all, our solar system isn't just a star and eight blobs.
毕竟，我们的太阳系并不是只有一颗恒星和八颗卫星而已。
Most of our neighborhood planets have moons, and half of them have rings.
我们附近的大多数行星都有自己的卫星，其中半数行星都有行星环。
So far, exoplanet rings, or exorings, have been pretty elusive.
目前为止，系外行星环（exoring）对我们来说是神秘莫测的。
But we've already found what might be the first set of exorings, and if we find more, we'll have a treasure trove of new information.
但我们已经发现了可能是成为第一批系外行星环的候选。如果我们能发现更多这样的候选，就有很多新信息有待探寻了。
In our solar system, astronomers hunt for planetary rings using a technique called stellar occultation, where something passes in front of a background star, blocking out some or all of its light.
在太阳系中，天文学家一直在搜寻行星环，用的技术手段叫行星掩星。所谓行星掩星就是有物体穿过某背景星的面前，所以阻挡住了部分甚至全部光源。
Since we can measure changes in brightness very accurately, astronomers can use occultations to spot things too faint or far away to be picked up otherwise.
鉴于我们可以精确测量亮度的变化，所以天文学家可以通过掩星来辨认太过模糊或者太过遥远的物体。
For example, we knew that Pluto had an atmosphere decades before New Horizons arrived because of occultations.
比如，我们都知道冥王星在几十年前是有大气层的，那时候还没有掩星现象出现，所以新视野也还没有形成。
They were used to discover the rings of Uranus, Neptune, and the minor planet Chariklo.
掩星现象可以用来发现天王星、海王星、小行星“女凯龙星”的发现。
Outside of our solar system, stellar occultations are so useful that they've been the most successful technique for discovering exoplanets.
在太阳系外，行星掩星是十分有用的，它是发现系外行星最为成功的方法。
It's usually called the transit method when used in planet hunting,
在搜寻行星的时候，这种方法通常被称为中天法。
but the basic principle is the same: as a planet passes in front of its star as seen from Earth, we detect a small dip in the star's light.
但其基本原则是一样的：当某颗行星穿过其恒星面前时，如果地球上可以观测到这一现象，那么我们就能监测到恒星亮度的减弱，哪怕再小的减弱也能监测到。
That dip is called the lightcurve, and all transiting planets have lightcurves with basically the same shape.
这种亮度的变化名为光变曲线。所有穿越恒星的行星都会有光变曲线，其形状都差不多。
So if astronomers see an unusual pattern, it might mean there's something extra blocking the star's light, like a ring!
所以如果天文学家看到了不同寻常的曲线模式，就可能意味着还有其他什么东西阻挡着恒星的光线，比如行星环。
Finding a ring would be awesome, but what it could tell us might be even cooler.
寻找行星环本身就很酷了，但行星环能提供的信息可能更酷。
During its 13-year mission, NASA's Cassini spacecraft revealed that Saturn's ring system is intricately related to both the planet and its moons.
在13年执行任务的历程中。美国宇航局的卡西尼号太空船发现，土星的环系跟行星以及其自己的卫星都有着千丝万缕的联系。
A gap, for example, could mean an unseen moon is embedded within the ring.
比如，如果环系有缺口，就可能意味着某颗看不见的卫星嵌在了环里。
Occultations of Saturn's rings revealed the narrow Keeler gap well before Cassini discovered a tiny moon named Daphnis orbiting inside it.
土星环的掩星现象揭示出土星存在狭窄的基勒环缝之后，卡西尼号才发现其内部有土卫三十五这颗小卫星。
On the other hand, a moving pattern of higher density, called a density wave, could reveal the presence of a moon orbiting outside of the rings.
另一方面，高密度的移动模式，即密度波，可能表明环外有卫星环绕。
Nearly all the fine detail in Saturn's rings is due to the gravitational sway of its many moons.
土星环里几乎所有的细节都是因为土星的许多卫星存在的重力影响。
With an exoplanet, if astronomers knew the mass of that moon, something that's possible with the transit method, the wave's shape could even reveal the density of the ring.
就系外行星而言，如果天文学家知道某颗卫星的质量（质量是无法通过中天法得出的），那么其波的形状甚至可以揭示出环的密度。
But wait! There's more.
惊喜远不止如此。
Cassini found that special density waves in Saturn's inner rings actually revealed the motion of material within the planet.
卡西尼号发现，土星内环中的特殊密度波实际上可以揭示出土星内部物质的移动情况。
Now, researchers are probably a long way from repeating those observations in another star system.
现在，天文学家很有可能需要很长时间才能在另一个恒星系统里重复做这样的观察。
We're still working on spotting whether rings exist at all; it's a lot harder to see what's happening in their internal structure.
因为我们现在仍然处在观测环是否存在的阶段，而要观测其内部结构中发生了什么，其难度要高出很多。
But it's a tantalizing hint of what the future might hold.
但这至少为未来可能揭示的知识提供了导向。
And the path to that future is already in motion, because astronomers might have found the first set of exorings back in 2012.
而我们已经走在通往未来的路上了，因为天文学家可能已经于2012年发现了第一组系外行星环。
The rings were found orbiting a planet with a name so bad I'm not even going to try to say it, so let's call it J1407 b for short.
这些行星环环绕的行星名字很拗口，我就不说全名了，大家可以简称它为J1407 b。
In the world of exoplanets, everything is over the top, and this system is no exception.
在系外行星的世界里，所有事物都异于寻常，该系统也不例外。
At dozens of times the mass of Jupiter, J1407 b is so large that it's tough to even be sure whether it's a planet or a failed star called a brown dwarf.
J1407 b的质量是木星的几十倍。由于其质量如此之大，所以很难确定它到底是一颗行星，还是未能形成恒星的失败品，即褐矮星。
The rings are no slouch, either.
这些环也不可小觑。
Based on their data, the researchers think that a total of 30 rings stretch about 120 million kilometers, a span more than 200 times larger than the rings of Saturn.
根据数据，天文学家认为，把所有环，即30个环加在一起，可以绵延1.2亿公里，是土星环的200多倍。
One study indicates that a gap between two of the rings could be caused by a moon up to 80% the mass of the Earth.
有一项研究表明，其中两个环之间的缺口可能是由一颗卫星造成的，这颗卫星的质量是地球的80%。
With their gigantic size and high density, some scientists wonder if it's even right to call them rings at all.
由于它们体型庞大、密度奇高，所以一些天文学家觉得称它们为环或许不够准确。
Instead, we might be seeing the remnants of a circumplanetary disk, the disk of material around a planet that gives rise to moons early in its life.
相反，我们看到的可能更像是环绕行星的圆盘残余物，像是行星附近由物质组成的圆盘。在其形成初期就有了多颗卫星。
Our solar system went through that process billions of years ago, but the J1407 system is only about 16 million years old.
我们的太阳系在数十亿年前就经历了这样的过程，但J1407体系却只有大概1600万年的历史。
It's probably not worth worrying about whether to call this material a ring or not until we have other examples to compare it to.
或许我们根本不必担心是否应该将这种物质称之为环，毕竟现在还没有其他的例子可以比对。
Which begs the question: if planets are common in the galaxy and rings are common around planets in our solar system, where are all the exorings?
我们应该问的是：如果太阳系星系中普遍存在行星，而行星附近普遍存在行星环的话，那系外行星环会在哪里呢？
Why have we found only this one example?
为什么目前为止我们只发现了这一个例子呢？
Part of the answer is that we need a new generation of technology to see them.
部分原因是：我们需要新一代技术才能观测到。
Just finding an exoplanet is still a pretty tricky task and rings are even harder.
寻找系外行星是相当艰巨的任务，寻找系外行星环就更为艰巨了。
But geometry is also working against us.
但几何学也在给我们找麻烦。
The transit method, which is our best, and possibly only, way to find exorings, only works when we're looking at a star system edge on.
中天法可能是我们目前寻找系外行星环最好的方法，但这种方法只在我们观测某恒星系的侧视图时才有效。
But models of planet formation suggest that planetary rings should also be edge-on in that scenario, making them nearly impossible to detect.
但行星的信息模型告诉我们，行星环在这种情境下也是侧视的，所以就不可能实现观测。
After all, Saturn's rings become almost invisible to a spacecraft orbiting the planet itself when viewed edge-on.
毕竟，土星环在侧视图呈现的时候，环绕土星飞行的太空船几乎是无法对其进行观测的。
From hundreds of lightyears away, we'll need to be looking at really big rings in a really obvious configuration to have a chance of seeing them anytime soon.
毕竟我们离那里有数百光年之远，所以我们需要从十分明显的角度来观测体型庞大的行星环，才有可能尽早发现新的行星环。
That would be a pretty unusual situation, so it makes sense that we'd be having so much trouble finding exorings even if they're all over the place.
十分明显的角度是不太容易出现的情况，所以我们也能理解在寻找系外行星环的路上为什么会有这么多的困难（不管行星环是不是到处都有）。
But, hey, if there's one thing exoplanets are awesome at, it's being unusual. So the hunt is on!
但正是因为系外行星环如此不同寻常，所以它才极具魅力呀。所以我们的追寻之路已经开启了。
Thanks for watching this episode of SciShow Space, and special thanks for our patrons on Patreon for making it possible!
感谢收看本期的《太空科学秀》，尤其要感谢我们的忠实粉丝支持节目。
If you'd like to help support our team and help us make more episodes like this, you can go to patreon.com/scishow.
如果您想助力支持我们的团队，并帮我们制作类似本期的视频，您可以登录patreon.com/scishow。
