The exosphere is the uppermost layer of the Earth’s atmosphere.
Only the lightest gases, mainly hydrogen, with some helium and carbon dioxide find their way into the earth’s exosphere.
The molecules in the exosphere are so thinly dispersed that they have as good a chance of escaping the atmosphere as colliding with another molecule.
If a molecule in the exosphere is moving fast enough to attain escape velocity, it would escape into space.
The exosphere is located about 500 to 1,000 km, or 310 to 620 miles above the Earth’s surface.
Since the exosphere is technically space, temperatures can reach thousands of degrees Celsius during the day, and close to absolute zero at night.
When non-scientists talk about “outer space,” they are actually describing the exosphere.
The word exosphere literally means “outer atmosphere”, from the Greek word “exo”, which mean outside.
How high the exosphere goes is debatable. Scientific evidence indicated that there is a sparce layer of atmosphere, hydrogen and helium, up to 8000 miles above the earth. Snd that would make the earths atmosphere go up to 8000 miles. Not all meteorologists buy into this theory, but, for those who do the belief is where there is an atmosphere tied to earth by gravity, regardless of how thin, then that is part of earths atmosphere.