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In places like southern Canada, a glowing, purple ribbon of light sometimes crosses the sky.
加拿大北部这样的地方，有时候天空中会出现紫色光带。
It's pretty faint, and it sometimes has these green spikes called the picket fence.
这种光带亮度微弱，有时候会出现绿色的尖状物，名为尖桩篱栅。
It's also pretty speedy, moving steadily east to west about six-and-a-half kilometers per second.
尖桩篱栅的速度也奇快，运动方向从东到西，速度可达近6.5km/s。
Citizen scientists and photographers have known about it for a long time, because it keeps photobombing their pictures of auroras.
民间的科学发烧友和摄影爱好者早就知道尖桩篱栅的存在，因为他们一直都抢着拍下这种极光现象的照片。
And after years of seeing it, they even gave it a name: Steve, after the scene from the movie Over the Hedge.
在拍摄了数年之后，他们甚至还给这种现象取了个名字——史蒂夫（强热散发速度增强），因为动画片《篱笆墙外》中出现了极光的场景。
But they just assumed it was a funny kind of aurora, or at least something similar.
但他们以前一直认为这只是一种有趣的极光，或者类似的东西。
Then, in 2016, Steve caught the attention of professional scientists, who realized this streak might be something new.
然后2016年的时候，强热散发速度增强吸引了专业科学家的注意，因为专业科学家发觉这种极光带可能并不同于以往。
And last Monday, one team published a paper in Geophysical Research Letters with the newest explanation for it.
上周一，某科学家小组在《地球物理研究通讯》上发表了一篇论文，对此事有了最新解释。
According to their results, Steve… is like nothing we've ever seen before.
根据此论文的结果，强热散发速度增强有点像我们从未见过的事物。
It might be a whole new kind of northern light.
这可能是一种全新的北极光。
Even though citizen scientists kind of named this streak as a joke, scientists decided to roll with it, and they formally called this light the Strong Thermal Emission Velocity Enhancement. Which is pretty amazing.
虽然科学发烧友们觉得这种极光只是个玩笑罢了，但专业科学家还是决定细细研究一番，他们还给这种极光起了个正式的名字——强热发散增速现象，这就让人颇有些震惊了。
They could immediately tell it was different from normal auroras for a few reasons.
专业科学家可以即可辨别出这种极光与正常极光的不同之处，原因如下：
First, auroras usually only appear at lower latitudes during periods of especially high solar activity, but STEVE is a consistently lower-latitude event.
首先，极光通常只会在太阳高度活跃期间出现在低纬度地区，但强热散发速度增强只会在低纬度出现。
And its shape and speed don't really match other auroras, which tend to be broader, undulating structures.
而且其形状和速度与其他极光也不吻合，会更宽一些，结构更波浪起伏一些。
Plus, auroras tend to be green or red; purple usually only shows up in extreme cases.
此外，极光一般都是绿色或者红色的；紫色只会出现在极端地区。
Because of this, scientists wondered if there was a unique mechanism at play.
鉴于此，科学家开始思索是否有一种独特的机制在起作用。
Earlier this year, one team published the first explanation for STEVE.
今年年初，某小组发表了一篇文章，对强热散发速度增强现象进行了解释。
They suggested it might be caused by something called a subauroral ion drift, or SAID.
他们认为，这种现象可能是由亚极光离子飘移引起的。
SAIDs aren't auroras: Instead, they're fast, westward flows of charged gas associated with solar storms.
亚极光离子飘移并非极光；它们速度奇快，是向西移动的带点气体，会与太阳风暴发生作用。
That sounds a lot like our purple streak, but STEVE doesn't only appear during solar storms, and it moves much faster than SAIDs typically do.
这听起来很像我们的紫光带，但强热散发速度增强在非太阳风暴期间也会出现，而且比一般的亚极光离子飘移速度都要快很多。
SAIDs also rarely produce visible light emissions. So in last week's paper, another team took a different approach to the mystery.
此外，亚极光离子飘移很少放出可见光。所以，在上周的论文中，另一个小组从不同的角度解释了这桩谜题。
Since the SAID hypothesis already had some holes in it, the group wanted to see if STEVE could be formally considered an aurora, even if it was an unusual one.
因为亚极光离子飘移假说已经存在一些漏洞，所以该小组想要查验强热散发速度增强是否可以归类为极光，就算不是常见极光。
Auroras happen when energetic electrons and protons from the Sun precipitate through the Earth's atmosphere, exciting those gases and making them glow.
极光发生的条件是：太阳放射出的高能电子和质子以高速穿越地球大气层，让这些气体变得活跃，并开始流动。
So if STEVE is an auroral event, then scientists should be able to detect these particles when the streak appears.
如果强热散发速度增强是极光现象，那么科学家就应该可以在光带出现的时候勘测到这些粒子。
The paper's authors used ground-based and satellite data taken during one of STEVE's 2008 appearances to try and hunt them down.
本文作者通过2008年发生强热散发速度增强期间从地面采集到的卫星数据来试图确定这一点。
Except, there wasn't much, at least, in the way of energetic particles.
不过，数据不是很充分，至少高能粒子不是很多。
So that rules out STEVE as an aurora. That means, at least right now, this purple light is in a class all its own.
所以这就排除强热散发速度增强是极光的可能性了。也就是说，至少目前来看，这种紫光是独一份儿的存在。
It's just… a STEVE, probably driven by its own special mechanism.
我们只能将它称之为强热散发速度增强，它八成是有自己的特殊机制的。
But that doesn't mean we'll stop investigating it.
但这并不意味着我们会停止研究强热散发速度增强。
The next steps are to study more STEVE events, since scientists have only really looked at two of them so far.
下一步计划是：研究更多的强热散发速度增强事件，因为科学家目前为止只观测了2个强热散发速度增强现象。
And ideally, that will help us not just understand this light, but how the Sun creates different kinds of auroras in general.
理想的状况是：这种研究不仅可以帮助我们理解这种光，还能让我们了解到太阳大概是如何产生不同种类的极光的。
While those scientists keep working on that mystery, another team is celebrating a new discovery.
虽然这些科学家尚未解开这个谜题，但还有一个科学家小组正在庆贺一项新发现。
According to a paper published in PNAS last Monday, researchers have found direct evidence of water ice on the surface of the Moon!
根据上周一《美国国家科学院院刊》发表的一篇论文，研究人员发现了直接证据，可以表明月球表面存在固态水。
And that could be big news for future explorers.
这对于未来的探索者来说是巨大新闻。
The new discovery was made thanks to Chandrayaan-1, a lunar orbiter launched in 2008 by the Indian Space Research Organization.
之所以能发现固态水，要感谢月船1号，这是一个月球的人造卫星，是印度空间研究组织2008年发射的。
Its payloads mostly focused on mapping and studying the Moon's composition, and it did some really cool science for almost a year before a communication failure ended the mission.
其载荷基本上关注的是绘制并研究月球的组成，月船1号在近1年的时间里做了许多很棒的科学研究，后来由于通信失败而终止了任务。
The data for this new paper specifically came from the orbiter's M3 instrument, or the Moon Mineralogy Mapper, which was built by NASA's Jet Propulsion Laboratory.
这篇新论文的数据来自卫星M3上的设备，也就是月球矿物质绘图仪，该设备是由美国宇航局的喷气推进实验室建造的。
It's a type of spectrometer, which means it measured the wavelengths of light that reflected off the Moon's surface and used them to determine composition.
月球矿物质绘图仪是一种分光仪，可以测量从月球表面弹射回的光的波长，然后通过波长来判断月球的组成。
About ten years ago, back when Chandrayaan-1 was still active, M3 found some evidence for water ice on the surface, which was really exciting.
大约10年前，当时月船1号还在执行任务，那时候月球矿物质绘图仪发现了一些证据，可以表明月球表面存在固态水，颇为振奋人心。
But the evidence was pretty indirect, and it wasn't obvious just how much ice there was.
但这些证据都是间接证据，无法直接证明有多少固态水。
Plus, that data included water that was part of hydrated minerals, so it wasn't pure ice or anything. But now, things seem different.
而且，这份含水的数据只是含水矿物的部分组成物质，所以并非纯净的固态水。但现在，情况似乎有变。
This newly-analyzed data directly confirmed the presence of that ice, and it also suggests that at least some of it could be pure water, although more observations would help pin that down.
这份经过最新分析的数据可以直接表明固态水的存在，同时也表明至少其部分组成是纯净水，虽然还需要更多的观察才能敲定。
These ice deposits are scattered around the Moon's north and south poles, and a lot of it is in shadowy southern craters.
这些固态水成分散落在月球的南北两极，还有很多在看不清的南方陨坑里。
There, it never sees the light of day, thanks to how the Moon is tilted relative to the Sun.
那里从来都是暗无天日，这是因为月球与地球之间的倾斜角度所致。
That keeps the ice from melting and makes the deposits relatively nice and accessible.
所以那里的冰就不会融化，那里的水也较容易采集到。
So far, we don't really know how all that ice got there or how old it is.
目前为止，我们还不知道那些水从哪里而来，以及来了多久。
But this icy discovery is really promising for future missions.
但这次固态水的发现给未来的任务带来了希望。
As of right now, NASA is planning to send people back to the Moon, so this ice could potentially become a source of drinking water.
目前为止，美国宇航局正计划将人送往月球，所以这些固态水很可能成为饮用水的来源。
But maybe more importantly, if we can split it into hydrogen and oxygen on a large scale, it could also be used for rocket fuel.
但可能更为重要的是，如果我们将这些水大量分解为氢和氧，那么就可以作为火箭燃料了。
The Moon could be an interplanetary gas station! Well, someday.
月球可以成为行星间的加油站，不过这是未来某天的事了。
There's still a long way to go, but thankfully, that ice doesn't seem to be going anywhere.
我们还有很长的路要走，但好在固态水会在原处等我们。
Thanks for watching this episode of SciShow Space News!
感谢收看本期的《太空科学秀》！
And thanks especially to our Patrons who make it possible for us to research new science and create this videos for you. Thank you!
尤其要感谢我们的忠实粉丝，支持我们的节目研究新科学，所以这些视频都是为你们而作的哦。谢谢大家。
And if your name is Steve or Chandrayaan, let us know in the comments, because awesome.
如果有人恰好叫史蒂夫或者月船的话，请在评论区留言让我知道哦，因为这两个名字很酷。
