What does the exosphere consist of?

Some scientists consider the thermosphere the uppermost part of Earth's atmosphere, and think that the exosphere is really just part of space. However, other scientists do consider the exosphere part of our planet's atmosphere. read more

The exosphere is the outermost layer of the atmosphere, starting around 200 km in altitude, where gases exist at a density so low, they’re measured in atoms and molecules per cubic unit. It consists mainly of hydrogen, with a little CO2, helium, and some oxygen thrown in. read more

Although the exosphere is technically part of Earth's atmosphere, in many ways it is part of outer space. Many satellites, including the International Space Station (ISS), orbit within the exosphere or below. read more