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For almost five years, the Curiosity rover has been exploring the bottom of Gale Crater on Mars.
好奇号探索火星盖尔陨坑底部已经有5年的时间了。
But if you look far enough back in time, you wouldn’t be able to explore it with just a rover — you’d need a submarine!
但如果将时间倒回到很久以前，用探测器是无法探索火星的——要用潜水艇！
You wouldn’t be looking at Gale crater anymore — it would be Gale Lake.
很久以前，盖尔陨坑不是现在的样子，可以称之为盖尔湖。
Scientists think that an ancient sea survived there for about 700 million years, from around 3.8 to 3.1 billion years ago.
科学家认为，古时候，有一片海洋在那里存在了近7亿年，大概是在3.8亿-3.1亿年以前。
And in a new paper out in the journal Science, researchers used what Curiosity’s learned about the rocks in Gale Crater to put together a history of the ancient lake.
在《科学》期刊上新发表的一篇论文中，研究人员通过好奇号了解的盖尔陨坑的情况勾画出了古代盖尔湖的历史。
Their results suggest that the lake had two distinct layers, each with its own chemistry.
他们的研究结果表明，盖尔湖有2个分开的层，每层的化学组成都不相同。
And for those 700 million years, the conditions in the lake probably would have allowed life to survive — if it ever did evolve on Mars.
在这7亿年间，盖尔湖里可能变得宜居——如果盖尔湖也有演变的话。
With the water long gone, the researchers needed to look for clues left behind in the planet’s rocks.
现在，盖尔湖里的水已经消失不见，所以研究人员需要寻找火星岩石中残留的线索。
Rivers and lakes are full of floating particles which settle onto the bottom over time to form sediments.
河水和湖水里都漂浮着很多分子。随着时间的推移，这些分子会沉积到底部。
Over time, these sediments pile up on one another, with each layer corresponding to a different period in the lake’s history.
慢慢地，沉积物会越摞越高，每一层都代表着不同的历史时期。
Eventually, the immense weight of these piles, plus the water above them, starts to compress the lower layers into solid rock, called sedimentary rock.
最后，随着沉积物的累积，加之水的压力，底层被压缩为岩石，也就是沉积岩。
Essentially, sedimentary rocks are the fossilized remains of the lake bed — and on Earth, that’s where we find most fossilized life, like dinosaurs.
最后，沉积岩就成了河床里留下的化石——就地球的情况而言，我们会在化石里找到许多生命的痕迹，比如恐龙。
Even though we haven’t found any evidence of life, Gale Crater’s sedimentary rocks can tell us a ton about what things were like in the lake billions of years ago.
虽然我们没有发现生命存在的证据，但盖尔陨坑里的沉积岩让我们了解到很多有关即使一年前盖尔湖里的情况。
Normally, to get to this ancient part of the rock record, you’d have to dig through kilometers of solid rock -- which would be pretty tough for a car-sized rover!
正常情况下，要挖到古时候留下来的沉积岩，就得挖数千米的岩石才能够到——这对于只有小汽车大小的探测器来说是个艰巨的任务。
That’s what made Gale Crater the ideal landing site for Curiosity: there’s a giant, 5.5-kilometer-tall peak smack in the middle of it, named Mount Sharp.
所以，盖尔陨坑就成了好奇号降落的绝好地点：盖尔陨坑中间有一个5.5千米高的大山峰，名为夏普山。
Mountains are like time machines, exposing all that old rock for easy viewing.
山就像时光机一样，可以轻而易举地展现出年头久远的岩石。
So to study hundreds of millions of years of history, all Curiosity needs to do is drive up the side of Mount Sharp and analyze rocks in different places.
所以，要研究数亿年前的历史，好奇号唯一需要做的就是研究夏普山各处的岩石情况。
When the researchers put together all that data, they found that Gale Lake was stratified, meaning that the water formed distinct layers, and that those layers had different amounts of oxygen.
研究人员将各种数据汇总后，就发现盖尔湖是分为多层的，也就是说，湖水形成了分隔的各层，而各层的含氧量也不同。
Plain oxygen was poisonous to early life on Earth, but compounds containing oxygen, like iron oxide or manganese oxide, might have been helpful for early forms of life as we know it.
纯氧对地球初期的生命而言是有不利作用的，但含氧化合物，比如氧化铁或者氧化锰可能就对生命的萌芽状态有益了。
With its varying levels of oxygen, Gale Lake could have had some of those compounds, which would’ve provided some life-friendly habitats.
由于盖尔湖的各层含氧量不同，就可能会有这样的含氧化合物，就会提供有利于生命延续的栖息环境。
The team also found that the Martian climate above the lake changed over time, bouncing between colder, drier conditions and warmer, wetter ones.
该研究小组还发现，盖尔湖上方的火星气候会随着时间演变，在寒冷干燥和温暖潮湿之间来回往复。
But bodies of water can make environmental changes like these less extreme.
但水体会引发环境变化，比如这种并没有那样极端的环境变化。
So despite the changes happening on the surface, the lake itself might have stayed habitable for long periods of time — a hopeful sign in our search for evidence of life on Mars.
所以，虽然湖水表面会发生一些变化，但盖尔湖本身在长期以内可能还是宜居的——这是一个积极的信号，表明火星表面可能会有生命存在。
Meanwhile, other astronomers are learning about mysteries much farther from home.
与此同时，还有一些天文学家正在对离我们较远的一些谜团进行研究。
In another recent paper published in the journal Science, a group of researchers studying a distant star did something remarkable: they proved Einstein wrong.
在《科学》期刊中刊登了另一篇论文中，一组研究某颗遥远恒星的科学家做了不得了的事情：他们证明了爱因斯坦的错误。
Well, they proved him both right and wrong.
准确的说，是证明爱因斯坦的正确之处和错误之处。
More than a hundred years ago, Einstein described how massive objects like stars bend the fabric of the universe as part of his general theory of relativity.
100多年前，爱因斯坦在其广义相对论中提出，像恒星这样的大质量物体会让宇宙的结构发生巨大的弯曲。
One of general relativity’s coolest predictions is that the light from far-off stars bends as it passes objects closer to us, in what’s known as gravitational microlensing.
广义相对论有一个最为出名的预测：来自遥远恒星的光在经过靠近地球的物体时会发生弯曲，这就是著名的微引力透镜。
Basically, a closer star’s gravity can act as a lens for the light from a more distant star, which leads to two major effects: the background star can look much brighter than usual, and it can also look like its position shifts a little in the night sky.
一般情况下，离我们近的恒星的引力相当于透镜，可以使遥远恒星发来的光发生弯曲，继而导致两种效果：遥远的那颗恒星看着要比平时更亮，而且它在夜空中的位置似乎也会发生些许的偏离。
Einstein thought that these effects would be too small for us to ever observe them.
爱因斯坦认为，这种影响微乎其微，我们甚至都观察不到。
But he had no idea that we’d develop space telescopes and digital imaging techniques that are impossibly sensitive compared to the photographic plates of his era.
但爱因斯坦当时不知道现在的我们可以研制出太空望远镜和数位成像技术，这种技术比爱因斯坦时代的成像技术灵敏了许多倍。
For decades now, we’ve been able to observe the brightening that comes from gravitational lensing, but one part of Einstein’s prediction remained stubbornly true: we just couldn’t see that shift in position.
在过去的几十年间，我们已经有能力观察到经过引力透镜作用的光，但爱因斯坦的部分预测依然不可撼动，那就是：我们无法通过技术观测到位置的变化。
It’s rare for stars to align in just the right way, and even when they do, the shift is so small that we haven’t been able to detect it.
恒星以正确的方式拍成一条线的现象是十分罕见的，即便这种情况出现，其位移也十分微笑，我们无法观测到。
At least, until now.
至少，现在的技术水平是观测不到的。
Using the Hubble Space Telescope, the team saw one star change the apparent position of another for the very first time.
通过使用哈勃望远镜，该小组首次观测到一颗恒星改变了另一颗恒星的视位。
In the process, they proved Einstein’s prediction wrong, but they found more evidence that his theory is right.
他们通过这个过程证明了爱因斯坦预测的错误之处，但他们发现，有更多的证据证明爱因斯坦理论的正确之处。
They also cleared up some major confusion about the star used as the lens.
他们还澄清了一些对起到引力透镜作用的恒星的重大误解。
Stein 2051 B is one of the closest and best-studied examples of a white dwarf, which is what stars like our Sun turn into at the end of the lives.
白矮星Stein 2051 B是离我们最近、研究最充分的一个例子。包括太阳在内的诸多恒星最后都要演变为白矮星。
But scientists have been really confused about its mass.
但一直以来，科学家对白矮星Stein 2051 B的质量都存在很大的疑惑。
Based on its radius, 2051 B should weigh about two-thirds as much as our Sun.
就其半径而言，白矮星Stein 2051 B的质量应该是太阳的2/3。
But previous estimates put its mass at only about half of the Sun’s — and that’s a big difference.
但我们之前的估测是：它的质量只有太阳的一半左右——这差别可就大了。
For a star with 2051 B’s radius and that lower mass to form, it would have to start off incredibly hot.
像白矮星Stein 2051 B这样有这么大半径以及这么小质量的恒星，应该温度极高才对。
In fact, some estimates suggested that in order to cool down to its current temperature, 2051 B would need to be as old as the universe itself … which made no sense, since our galaxy is about 600 million years younger than that.
实际上，根据一些估测，要使白矮星Stein 2051 B的温度降低到现在的水平，就需要白矮星和宇宙有同样的年龄……但这也不可能，因为整个太阳系都是在宇宙形成的6亿年后才形成的。
Based on how 2051 B bent that background star’s light, the researchers were able to get a much more accurate measurement of the white dwarf’s mass.
根据白矮星Stein 2051 B将背景星光芒弯曲的程度，研究人员可以更精确地估测出白矮星的质量。
And it turns out that it does weigh about two-thirds as much as the Sun.
结果就是：其质量确实是地球的2/3左右。
That’s a win for understanding the lives of stars and a win for general relativity — all around, a pretty good day for astronomy!
这是我们对恒星生命周期理解的胜利，也是广义相对论的胜利——这对天文学来说是重要的一天！
Thanks for watching this episode of SciShow Space News, and thanks especially to our patrons on Patreon who help make this show 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。
If you want to help us keep making stuff like this, you can go to patreon.com/scishow.
如果大家想要为我们的节目贡献一份力，可以登录patreon.com/scishow。
It’s just a place where you can give us a little bit of that coffee money.
相当于请我们喝了杯咖啡。
You don’t need that coffee!
一杯咖啡，随手之举啦！
What’s that.. it’s just gonna make your stomach upset. That’s how I feel. I love coffee.
咖啡可以让人的胃肠躁起来，这是我对咖啡的理解。我是个咖啡控哦。
Also, if you want to support us just by watching and sharing, that’s fantastic!
当然啦，如果大家想通过观看并分享我们节目的方式来支持我们的话，那是最好的啦！
You can find us at youtube.com/scishowspace.
观看我们的节目，可以登录youtube.com/scishowspace。
