Earth atmosphere is divided into many distinct layers. We live in troposphere, this is the thickest side of atmosphere. Above it we have stratosphere then mesosphere, thermosphere and the end exosphere.
The exosphere is the most outermost layer of earth’s atmosphere.
This layer start at 500 km above the earth’s surface and goes about 10000 KM.
The air is extremely thin in exosphere.
The layer below exosphere is thermosphere and the boundary between the two is called thermopause.
The term “Exo” means outside and the same term is used to describe insects part e.g “exoskeleton” , hard shell on out side of the body.
This layer is about 6,200 miles thick that is about 10k kilometers.
This layer is filled by gases like hydrogen and helium and these are very spread out , it is no air to breathe and temperature is very cold.
This layer is perfect for placing satellites because due to thin air, satellites can orbit with out any friction or disruption.
Due to thin air, the molecules do not collide with each other like they do in lower atmosphere.