Observing Sunrise on Small Exoplanets

The Milky Way is teeming with planets bigger than Earth but smaller than Neptune. With no such objects in our own Solar System, our understanding of the composition, formation, and potential habitability of these alien worlds remains sketchy. After presenting the rough portrait provided by
measurements of their masses, radii, and orbits, I will highlight how observations of existing planets’ atmospheres can help clarify the picture. However, out best chance to fill in the details will be to
enlarge the known sample of small planets transiting nearby, small stars. Such easy-to-observe systems would be the best targets for atmospheric characterization with the James Webb Space Telescope or the enormous ground-based telescopes now under construction. I will report
progress from two ongoing efforts to find these new exoplanet laboratories: the ground-based MEarth Project, searching the smallest stars for cool transiting planets, and the all-sky Transiting Exoplanet
Survey Satellite mission, launching in 2017 to find the nearest and brightest transiting exoplanet systems.