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

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

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

That's the terminator.

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

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

Our planet orbits the sun at a 23.5 degree angle.

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.

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

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

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

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

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

how galactic ice volcanoes erupt on Enceladus.

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