- Solar System Objects
- Planetary Objects
- Planetary Processes
- Planetary Miscellaneous
1. What makes an atmosphere? How can gases escape from a planet?
How do planets lose their atmospheres? There are several ways: a large impact can literally blow off the atmosphere (probably happened to Mars). When you heat up the molecules in an atmosphere, the molecules move faster and some of them can escape (this is how we lose hydrogen). The hotter the atmosphere, the more molecules can escape. The smaller the object, the lower the gravity, so the escape velocity is lower and it is harder to retain an atmosphere (Moon and Mercury). Finally, you can lose atmosphere to the surface. The atmosphere can condense onto the surface (rain and snow). On Earth, much of the carbon dioxide that is normally generated is dissolved into the oceans.
2. How does an exosphere differ from the atmosphere?
3. What causes the atmosphere to change so drastically from planet to planet?