Part 6/10:
Because Mercury has a very thin exosphere—a sparse layer of particles gravitationally bound to the planet—it cannot retain atmospheric gases for long. The exosphere, composed mainly of hydrogen, oxygen, sodium, and other elements, is constantly replenished by processes such as solar wind interactions and micrometeoroid impacts. When the solar wind hits Mercury, it strips away some particles, creating a characteristic tail or "atmospheric breeze" disappearing into space.