The detection of planets around other stars is undoubtedly one of the triumphs of modern astronomy. Not only do these planets prove that our solar system is not unique, they also reveal many new physical and dynamical characteristics that are unseen among the plants of our solar system and are unexplainable by the conventional theories of planet formation and dynamics. The challenges associated with these discoveries have made astronomers revisit planetary theories and have revolutionized our understanding of the formation and evolution of planetary systems.
Almost two decades after the discovery of the first extrasolar planet, and with now more than 700 of these objects having been discovered, these challenges still continue. On the observational front, despite breakthroughs such as imaging giant planets (e.g. HR 8799), detecting planets in Laplace resonance (e.g. GJ 876), and discovering planets in circumbinary orbits (e.g., Kepler 16b), a major shift has been made towards a more challenging task: detecting Earth-sized planets or super-Earths in the habitable zones of solar-type and smaller stars. Several large surveys such as HARPS, MEarth, M2K, and LCES, are already producing promising results using ground-based telescopes. The successful operation of the CoRoT and Kepler space telescopes is also making significant contributions by detecting several planets including Kepler 10b and the most prominent transiting super-Earth, CoRoT7b.
On the theoretical front, the challenges are even larger. Despite more than a decade of work on the formation and dynamical evolution of extrasolar planets, many fundamental issues are still unresolved. As in our solar system, it is not clear how extrasolar giant planets are formed. Nor is it fully understood how some of these planets acquired high orbital eccentricities, why some have very large semimajor axes, and in regard to the formation of terrestrial/habitable planets, it is not evident how the migration of giant planets affects the formation of smaller bodies in those systems. With the discovery of several super-Earths during the past few years, fundamental theoretical work is also underway to understand the interior dynamics of these bodies, as well as their atmospheres and magnetic fields, and the connections between these properties and the habitability of super-Earths and the possibility of the detection of their biosignatures.
With their continuing operation, the CoRoT and Kepler space telescopes are expected to pave the road for arriving at answers to many of these questions. By the time of IAU General Assembly in August 2012, CoRoT will have reached maturity and is expected to have discovered many more super-Earth planets. Kepler will also have been operating for more than three years, and given its capability in detecting Earth-like planets in the habitable zones of Sun-like and smaller stars, it is expected to have detected many potentially Earth-like planets. Similarly, with the rate at which small planets are detected by ground-based telescopes, many more ground-breaking discoveries are expected to be made by these surveys within the next two years. The General Assembly is therefore a very timely occasion to have a symposium on the advancements made in extrasolar planetary science, in particular on the formation and detection of terrestrial and habitable planets. The aim of the symposium is to have a diverse scientific program covering topics related to habitability and the challenges associated with the formation and detection of habitable planets. Our program consists of a series of invited talks and contributed oral and poster presentations through which speakers will present the current state of research on the habitability of Earth and the progress made towards its associated challenges. The symposium will also foster discussions on the implications of this research for detecting similar planets around other stars. This symposium is supported by the Division III (Planetary Systems Sciences) of the International Astronomical Union, and its Commission 51, Bioastronomy.