What term describes the sweeping of atmospheric gas particles into space by the Sun?

• A. Erosion
• B. Solar wind stripping
• C. Photodissociation
• D. Sublimation

Answer: (B)

This question hinges on how the Sun can remove atmospheric particles from a planet. The Sun emits a stream of charged particles—the solar wind—that continuously bathes each planet. When a planet has a weak magnetic field or lower gravity, these energetic particles can interact with the upper atmosphere and impart enough energy to atmospheric molecules to push them beyond the planet’s gravitational hold, effectively sweeping them into space. This mechanism is described as solar wind stripping. It helps explain why some planets lose their atmospheres over time and why others retain theirs more easily.

Erosion would refer to wearing away of surface material, not atmospheric loss to space. Photodissociation is the breaking apart of molecules by sunlight, not the removal of gas into space. Sublimation is a phase change from solid to gas at the surface and doesn’t describe removing atmospheric gas into space.