The possibility of life beyond Earth is an ancient source of human wonder. If we find such life, it is likely to be on a planet or a moon, and the science of extrasolar planets has blossomed from the dream of a few dedicated planet hunters to become one of the core disciplines of astrophysics for the foreseeable future. I will discuss how we can learn about the composition and temperature of worlds around other stars -- which is a crucial part of the the quest for habitability -- and how we will eventually be able to search for signatures of life. I will also discuss the life cycle of planetary systems as a whole, including thermal and chemical changes, and orbital evolution. In particular, Jupiter will eventually become much hotter (a "hot Jupiter"), and if it were somewhat closer to the Sun it would eventually be tidally engulfed by the future-red-giant Sun.
David Spiegel (Astrophysics Department, Institute for Advanced Study, Princeton, NJ)