Planetary Science seminars

Ania Liu examines gravitational-wave lensing as a probe of compact objects, dark matter and cosmic large-scale structure. Propagation over cosmological distances can distort signals, but identifying lensing in observations requires disentangling those distortions from uncertain waveform models and other astrophysical effects. The talk describes this phenomenology and the ambiguities it creates for interpretation, then presents recent methods and results from lensing searches using LIGO–Virgo–KAGRA data.

Lisa Dang explores how observations reveal the three-dimensional atmospheres and climates of close-in exoplanets. Kepler and TESS have established a diverse population that tests theories of planetary formation and evolution. Tidally locked short-period planets offer strong atmospheric signals but their large day–night contrasts make one-dimensional interpretations inadequate. Measurements from JWST and precise ground-based observatories can expose these spatial differences and determine whether an atmosphere is present. The talk reviews discoveries about intensely irradiated planets and explains how the same observational techniques now investigate temperate rocky worlds and their potential habitability.

Didier Queloz traces the transformation of planetary science following the 1995 discovery, with Michel Mayor, of a giant planet orbiting another star. Thousands of subsequent discoveries have revealed planets ranging from gas giants to smaller rocky bodies, stimulated new instruments and changed theories of planetary formation and evolution. The diversity of exoplanet systems challenges assumptions drawn from the Solar System and raises questions about how common systems like ours are. The lecture also considers the possibility of searching planetary atmospheres for evidence of life.

Olivier Guyon explains the physics and engineering of extreme adaptive optics for directly imaging exoplanets. Atmospheric turbulence distorts incoming wavefronts; sensors measure those distortions and deformable mirrors apply compensating corrections. The lecture covers guide stars, fast detectors, actuators, real-time computing and control systems. Extreme adaptive optics requires correction rates above a kilohertz, mirrors with more than a thousand actuators and nanometer-scale measurements of optical aberrations. Guyon describes how integrated systems suppress and calibrate unwanted starlight, including approaches developed with the Subaru Extreme Adaptive Optics system. These advances support efforts to equip extremely large telescopes to image potentially habitable planets.