The exosphere is the outermost layer of Earth’s atmosphere. It’s a vast, sparsely populated region that gradually fades into outer space. Unlike the layers below it, the exosphere doesn’t have a clear upper boundary. It’s so thin that molecules can escape into space without colliding with each other.
Key characteristics of the exosphere
- Thin atmosphere: The air in the exosphere is extremely thin, with very few atoms and molecules.
- No defined upper boundary: The exosphere gradually fades into outer space.
- Escape velocity: Lighter atoms and molecules, like hydrogen and helium, can reach escape velocity and leave Earth’s gravity.
- Satellites and space stations: Many satellites and space stations orbit in the exosphere.
- Geocorona: A faint glow of ultraviolet radiation scattered by hydrogen atoms in the exosphere.