No, not a time traveling humanoid robot, but a line where its light and dark side meet.

不是那可穿越時空的擬人機器人，而是一條明暗交界的線。

On Earth we see the Sun rise from the East and set in the West.

我們在地球上看著太陽從東邊升起，由西邊落下。

But if you were looking straight down from space, you would see half the planet lit, and the other half in total darkness.

但若直接從外太空向下看，你會看到整個星球一半是亮的，一半則完全在黑暗中。

That's the terminator.

這就是晨昏線。

The terminator, also called solar terminator or the “twilight zone” moves around our planet once a day.

晨昏線，又稱晨昏圈或「曙暮光區」，每天繞我們的星球一圈。

The Earth is constantly rotating, and it's got a little tilt to it.

地球不停地旋轉，又有點傾斜。

Our planet orbits the sun at a 23.5 degree angle.

整個星球以 23.5 度傾斜繞著太陽運行。

That axial tilt causes one pole to be facing the Sun, and the other pole facing away, and that gives our planet its four seasons.

轉軸傾斜導致某一極朝向太陽，另一極則朝向較遠處，四季因此而生。

The terminator is a guide for solar-powered low earth orbit satellites.

晨昏線是太陽能近地軌道衛星的指引。

They ride the line in total sunlight to take pictures of Earth.So while the terminator

衛星全程在陽光下運行，以利拍攝地球照片，所以，雖然晨昏線

doesn't really do anything, it is good for science!

沒什麼實際作用，卻對科學有很有幫助！

You can watch new episodes of Space Crafts right here every Wednesday.

歡迎收看《Space Crafts》，我們每周三推出新集。

In this edition, we break out everyone's favorite elementary school science experiment to explain

這系列中，我們會解說受大家喜愛的小學科學實驗，並解釋

how galactic ice volcanoes erupt on Enceladus.

土衛二上的銀河冰火山為何爆發。

Thanks for watching and make sure to subscribe!

感謝您的收看，請記得訂閱本頻道！