April 5, 2018,
noon - 1 p.m.
The number of planets we know increased by two orders of magnitude in the past decade. Many of the planets discovered beyond our solar system, i.e., exoplanets, have surprising traits, including having orbital periods of a mere few days, being larger than Earth and smaller than Neptune, and having atmospheric compositions where data suggest deviation from chemical equilibrium. These discoveries necessarily reorient our study of planetary atmospheres. I will discuss how observations of exoplanet atmospheres help us better understand the physical and chemical processes that control planetary atmospheres as well as the evolution of planets. For example, strong stellar irradiation and intermediate size of some exoplanets enable the formation of helium atmospheres, resulting in distinctive remote sensing spectral features. Observations of Hubble and JWST thus provide the opportunity to study the atmospheric evolution of super-Earths and sub-Neptunes. Looking ahead, I will conclude by describing pathways forward to characterize cold planets at wide orbital separations and search for potential signs of habitability from these distant worlds.