The study of exoplanets has emerged in the last decade to be one of the most exciting new areas of astronomy and planetary science. Since 1995, more than 280 planets outside the solar system have been discovered, mostly by radial-velocity methods. Collectively, they span a huge range of masses and orbital distances, have been found around most stellar types, and have led to major revisions in our ideas of how and where planets form and what their structure is. The majority of these planets are gas giants, but more than 40 are of Neptune mass and lower. Forty-nine are known to transit/eclipse their primary star, and it is for these that we have physical parameters such as radius and mass. A subset of the close-in transiting giants has now been detected directly at secondary eclipse and at various orbital phases by the Spitzer Infrared Space Telescope and NICMOS on the Hubble Space Telescope, providing the first measurements of extrasolar planetary atmospheres and compositions. To interpret these data, theorists have developed models for planet formation, orbital interaction and dynamics, evaporation due to stellar irradiation, atmospheric circulation and global heat transport, atmospheric structure and spectra, phase light curves, the equations of state of their interiors, molecular chemistry, radius evolution, and tidal effects, to name only a few topics.

Program Goals: This program is being conducted to accomplish two overarching goals. First would be the theoretical synthesis of the vast amount of information already gathered to create a global picture of the field and its future. One byproduct of this effort would be the mutual education of theorists and observers to create a more coherent discipline of comparative planetology. This could help in the design of incipient NASA and ESA exoplanet research programs and could also help guide future ground-based and space-based observing campaigns. Second, and perhaps more important, would be the further integration of planetary science into the astronomy of exoplanets. To date, exoplanet research has been driven by astronomers, while planetary scientists have by and large focused almost exclusively on our solar system. However, the expertise and accumulated wisdom in planetary science is vast, and the merger of its perspectives and knowledge with the new astronomical discoveries being made outside the solar system would greatly enrich both.

• 1) to summarize the current understanding of this very rapidly evolving, highly interdisciplinary field;
• 2) to present the latest ideas, models, techniques, and observations;
• 3) to foster the interaction of the planetary science and astronomical communities; and,
• 4) to identify crucial objectives and problems that will enable clear, coherent advancement of the field in the coming years.

Questions should be directed to one of the program coordinators.

Conference: There will be a conference associated with this program from March 29 to April 2.