Physics and Astronomy Colloquium

When extrasolar planets are observed to eclipse their parent stars, we are granted unprecedented access to their physical properties. It is only for these systems that we are permitted direct estimates of the planetary masses and radii, which in turn provide fundamental constraints on models of their physical structure. Furthermore, such planets afford the opportunity to study their atmospheres without the need to spatially isolate the light from the planet from that of the star. I will review the most recent results, and then describe a new observatory that will survey 2000 nearby low-mass stars with a sensitivity to detect rocky planets orbiting within their stellar habitable zones.