The geophysics occurring in the interior of planets strongly affect what happens on their surfaces and in their atmospheres. How do rocky planets like Earth get their atmospheres? It’s possible that atmospheres come from asteroids or comets that crashed into surfaces and thereby delivered chemical ingredients that vaporized on impact. Another possibility is that gases come from inside planets. Earth’s atmosphere, for instance, developed in part from volcanic eruptions that released millions of tons of gases into the air. But all these gases would have been blown away from Earth, like they were at Mars, by cosmic winds and solar flares if not for our planet’s gravity and its magnetic field, which is created by a geologic dynamo in Earth’s core. Likewise, weathering by the atmosphere can erode surface features and promote unique chemistry that is essential for life as we know it. SEEC scientists are working to understand this interplay among interiors, surfaces and atmospheres in the unique environments of exoplanets.