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火星上的“悬河”?!

UPSIDE-DOWN Rivers On Mars?! (Response to MinutePhysics)

Hi! This is Amily from Minute Earth
大家好 我是来自《分钟地球》的Amily
A little while back, Herry made this great minute physics vedio
不久前 Herry制作了一期《分钟物理》的精彩视频
about how the werid symmetry of light and shadows on landscape
讲述了地面上光影的奇异对称
can make it really hard for your brain to tell
是如何让大脑很难分辨
which features are popping out and which ones are dented in
哪些地形特征是凸起的 哪些是凹陷的
Especially if you are not sure where the light is coming from.
当不知道光线从哪个方向照射过来时尤为如此
This re-ignited an old debate we had here at Minute Earth,
这再一次引发了我们之前经常在《分钟地球》进行过的一项争论
about this photo of the surface of Mars
就是关于这张火星表面的照片
That sinuous pattern on the landscape is an ancient stream channel
地表上的蜿蜒图形是一条古老的河道
which is cool because It means that the liquid water used to flow on Mars.
看起来很酷 因为这意味着火星表面曾经有液态水流过
But that crater above it has a shadow In the top left ,
但河道上方大坑的左上角有一片阴影
which means the light in the image must be coming from the top left
这意味着照片里的光线一定是从左上方照射过来的
would seem to suggest that
这也似乎表明
the stream channel is actually sticking up above the surrounding landscape.
与两岸地势相比 河道实际上是向上凸起的
But…that can’t be right, right?
但这肯定不对 是吧?
I mean, river channels should obviously be valleys,
我是说 河道显然应该是谷地
since they’ve been carved into the ground.
因为它们是凹陷于地面的
This seem like such a basic fact to me that
这对我来说就像是基本常识
even when everyone else on my team said they saw this as a ridge,
即使是团队中的其他人都认为这是山脊
my brain kept telling me it was a valley.
我的大脑仍不断告诉我这是山谷
It turns out that, not only was my brain lying to me,
原来 不仅是大脑欺骗了我
but this stream channel is an example of a weird geological process
而且这条河道展示了一种特殊的地质作用过程
that essentially turns landscapes inside out, creating inverted relief.
这种地质作用本质上是将地形凹面变成凸面 形成倒转地形
If you live in a cold climate, you may have actually seen something
如果你生活在寒冷气候地带 你可能会
like this happen with compacted footprints in the snow –
在雪地里的脚印上看到过这样的情况发生
as the sun melts the fluffier snow around them, they can end up sticking out, like this.
当太阳融化了脚印周围蓬松的雪时 脚印就会凸出来
The same thing can happen to a river valley.
河谷也会出现同样的情况
For instance, say you’ve got a stream running through a desert.
假如有一条流经沙漠的河流
Sometimes there is so little rain that the stream dries up.
有的时候因为降雨量太少 河流就干涸了
As it does, some groundwater is actually drawn upward by capillary action,
与此同时 部分地下水通过毛细作用被抽取到上面
and as it rises and evaporates,
随着水分的上升和蒸发
dissolved minerals in it are left behind and precipitate out,
溶解在其中的矿物质残留下来后被析出
coating the sediments in the riverbed and cementing them together.
它们包裹着河床的沉积物 并把它们粘结在一起
As the stream flows and dries up over and over again, more and more cement accumulates,
随着河流的反复流动与干涸 越来越多的固结物堆积下来
making the riverbed harder and more resistant to erosion than the surrounding rock.
使得河床比周围岩石更坚硬 更耐侵蚀
Over the eons, wind erodes that softer rock,
很久以后 风侵蚀了较软的岩石
turning the channel into an inverted version of its former self
把河道变成了与原来相反的样子
We can’t know exactly how this riverbed got turned inside out
我们无法确定火星的河床是怎么凸出来的
without getting down on the ground and digging around a little,
除非在周围的地面上挖掘一下
but we can make some pretty good guesses by studying inverted relief on our home planet.
但是通过对地球家园地形倒转现象的研究 我们可以做出一些推测
You can even find your own examples on Google Earth;
你甚至可以在谷歌地球上找到一些实例
just be warned that trying to figure out what’s right side up and upside-down
不过要注意的是 要搞清楚到底哪一面才是真正的凹面和凸面
will turn your brain inside-out.
会让你的大脑晕头转向
Hi, this is Ever and I illustrated this video.
嗨 我是Ever 是我绘制了这个视频
Lots of you have asked how I create animated effects like this one.
很多人都问我是如何制作出这样的动画效果的
It’s not magic;
这可不是魔法
in fact, it’s pretty easy to do if you’ve got the right tools and the right teacher.
实际上 如果有正确的工具和合适的老师 这就很容易做到
I was never one for formal school,
我从没有在学校里正式学过动画
but the online classes from experts at Skillshare are perfect
但是Skillshare上的专家在线课程是非常不错的
if you’re a self-directed learner like me.
前提是你像我一样 也是一位自学者
You can try out skillshare’s impressive library of 17,000 how-to classes on
你可以试看Skillshare上17000种的优秀知识课程
everything from video editing to T-shirt design.
从视频剪辑到T恤设计 应有尽有
The first 200 people to click the link in the description will get a 2 month free trial.
前两百位点击视频介绍中链接的用户 将获得两个月的免费试用期哦

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视频概述

火星上会有倒悬河吗?一起来看个究竟!

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收集自网络

翻译译者

fionaC

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视频来源

https://www.youtube.com/watch?v=yy5UpVoQDJw

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