For centuries, people have wondered whether other stars have planets, and whether those planets might harbor life. Within the last few decades, it has become possible to make progress on these timeless questions.  Exoplanetary science --- the study of planets around other stars --- is one of the newest and most rapidly growing branches of astrophysics.  Princeton is home to a vibrant research program in this field, including theoreticians, observers, and instrument builders for ground and space-based observatories.  In addition to the faculty named below, there are currently about 7 graduate students and 8 postdoctoral scientists who work on planetary astrophysics, at Peyton Hall and the Institute for Advanced Study.

Gaspar Bakos's group builds innovative instruments for detecting exoplanets and, more broadly, exploring the domain of bright and time-variable astrophysical phenomena. They run the ongoing HATNet and HATSouth surveys, which search for transiting planets using a network of custom-built small telescopes around the world. They have discovered nearly 100 planets, including some of the most exotic and intensively studied planets. His most recent initiative is HATPI, which will continuously image one-quarter of the celestial sphere (corresponding to a solid angle of pi radians).

Adam Burrows studies the theory of exoplanetary atmospheres, interiors, and evolution over billions of years, with a strong focus on those phenomena and physical characteristics that can be investigated using new data and experimental techniques.  Some recent work by his group includes studies of planetary mass loss due to stellar irradiation, and optimizing exoplanet observations with the James Webb Space Telescope and WFIRST. In addition, he works on the physical and chemical theory of brown dwarfs and their relation to gas-giant planets.

Josh Winn's group performs optical and infrared observations to study exoplanets, especially those in which the star and planet eclipse one another.  Recent work has focused on the orbital architecture of planetary systems: the sizes, shapes, and orientations of the orbits, and the stellar obliquity.  He was a Participating Scientist in the NASA Kepler mission and is a Co-Investigator in the Transiting Exoplanet Survey Satellite, scheduled for launch in late 2017.

Jeremy Goodman and Scott Tremaine study gravitational dynamics in both the solar system and extrasolar planetary systems, with particular focus on the long-term stability of planetary systems, protplanetary disks, planet formation, comets and other small bodies, and tidal interactions between stars and planets.

Robert Vanderbei develops optical systems for extremely high-contrast imaging, for ground and space--based telescopes. David Spergel is deeply involved in planning WFIRST, a future NASA mission that will (among other things) detect exoplanets through direct imaging and gravitational microlensing. Spergel is co-chair of the WFIRST Science Team.

Ed Turner has worked in many areas of exoplanetary science, including direct imaging, astrobiology, and statistical problems relating to exoplanet detection and population studies. He and Gillian Knapp participate in the Strategic Exploration of Planets and Disks with Subaru (SEEDS), a major study of planets and planet-forming disks with the adaptive optics systems at the Subaru telescope. This work continues with the deployment of CHARIS, which will explore nearby stars for giant planets.  Turner and Bruce Draine are actively involved in the Breakthrough Starshot Initiative, which has the long-term goal of sending a miniature spacecraft to Alpha Centauri.

Christopher Chyba's astrophysical research centers on solar system exploration, and the search for life on other planets and moons.  He is particularly interested in understanding the complex and often startling properties of icy satellites in the outer Solar System.  He has also worked on the problem of preventing Mars and other solar-system bodies from being contaminated by terrestrial organisms.