I will discuss a few of the processes by which atmospheric constituents escape the gravity wells of objects in our solar system and beyond.
Though planetary atmospheres are largely gravitationally bound, individual particles nonetheless escape from objects in space, in some cases at significant rates. Measuring this outflow provides us with a unique fingerprint of processes that occur in the atmospheres, surfaces, and sub-surfaces of solar system objects. Atmospheric escape is also relevant to planetary evolution, as it can transform climates over long time scales.
One important mechanism for atmospheric escape is the transfer of momentum from the flowing solar wind to atmospheric particles. I will discuss the physics of some processes by which this momentum transfer occurs, utilizing recent observations from the Moon, Mars, and comets as illustrative examples.