The sky is that huge blue globe covering the earth. It is made of air and clouds. It is currently 250 miles thick. There are five layers of the sky:

Troposphere: where most clouds are

Stratosphere: where Mt. Everest’s peak is

Mesosphere: where the D-Layer is

Thermosphere: where the rest of the ionosphere is

Exosphere: Basically outer space

The ionosphere is where northern lights appear from those cosmic ray thingies.

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