This is a picture which shows the Earth, its atmosphere (the clouds are likely in the troposphere and stratosphere), the limb of the Earth (the dark blue curve/edge which is the mesosphere and thermosphere), and the dark blue to black region of space (where our exosphere extends out to...).
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Image courtesy of NASA
Very high up, the Earth's atmosphere becomes very thin. The region where atoms and molecules escape into space is referred to as the exosphere. The exosphere is on top of