Our planet has a terminator.
我们的星球有一位终结者O,N%--sW^oHm。
No, not a time traveling humanoid robot, but a line where its light and dark side meet.
不，它并非一个穿越时空的人形机器人，而是光明与黑暗的交界线O3TnPmsEfx1。
On Earth we see the Sun rise from the East and set in the West.
在地球上，我们看到太阳从东边升起，从西边落下3vdb8~jIrVh~W4。

But if you were looking straight down from space, you would see half the planet lit,
但如果你从太空垂直向下看，你会看到地球只点亮了一半，
and the other half in total darkness. That's the terminator.
而另一半则完全处在黑暗中.1)M@LCx_E。那就是“终结者”5s7mxWxWJL。

The terminator, also called solar terminator or the “twilight zone” moves around our planet once a day.
这位“终结者”，又称“太阳终结者”或“暮色地带”，每天绕地一周JQ.aGF)^ljmczNvZtGd。
The Earth is constantly rotating, and it's got a little tilt to it.
地球一直在旋转，而且略微倾斜)qMJ.ow21,。
Our planet orbits the sun at a 23.5 degree angle.
我们地球的黄赤交角是23.5度e)@c4fF67%。
That axial tilt causes one pole to be facing the Sun, and the other pole facing away, which gives our planet its four seasons.
这种轴向倾斜，使得地球一个磁极面向太阳，而另一个磁极背向太阳，由此形成了四季AZDX_tmKQ(v。
The terminator is a guide for solar-powered low earth orbit satellites.
这位“终结者”是太阳能低地球轨道卫星运行的基准UHbg0fL^Q)Lz;A。

They ride the line in total sunlight to take pictures of Earth.
它们在全日光照射下，沿晨昏线，拍摄地球照片+zB2;2zrnR#nHU5lFu4。
That constant sunlight is useful for collecting images, monitoring weather and gathering data on climate change.
这种持续不断的日照非常有用，有了它我们可以收集图像，监测天气，还可以收集气候变化数据6o]Xr&[1Yis^wt8~wp。
So while the terminator doesn't really do anything, it is good for science!
所以虽然“终结者”（看似）什么都没有做，却助力了科学（研究）！
You can watch new episodes of Space Crafts right here every Wednesday.
每周三，你可以在这里观看最新一集的Space CraftsqFeN4~BGlTQoRjd。
In this edition, we break out everyone's favorite elementary school science experiment to explain how galactic ice volcanoes erupt on Enceladus.
在这期节目中，我们深入大家喜爱的小学科学实验课，来为大家阐释银河系中的冰火山，如何在土卫二上爆发&Xrs5nxzkADlyAz+^F。
Thanks for watching and make sure to subscribe!
感谢观看，欢迎订阅！