Planetary Science seminars

Marta Bryan explores what gas giants reveal about the formation and evolution of planetary systems. Their brightness and mass make them useful observational targets, and their gravitational influence can reshape the orbits and environments of smaller planets. The seminar combines several approaches. High-resolution spectroscopy of directly imaged planets measures rotation and obliquity, providing evidence about angular-momentum evolution. Radial-velocity searches for Jupiter-like companions to known inner planets probe how giant planets affect system architecture and inform the search for habitable worlds. The presentation also introduces observational work on planetary interiors and magnetic fields as further ways to test formation models.

Planets form from dust embedded in gaseous protoplanetary disks. Hydrodynamic instabilities can hinder growth by stirring turbulence, yet also help by creating structures that collect solids and promote planetesimal formation. Min-Kai Lin will discuss analytical and numerical studies of the vertical shear instability and convective overstability, their interactions with dust, and generalisations of the streaming instability to disks with accretion or magnetic fields. The seminar examines how these processes alter the conditions for concentrating solids and the challenges that remain in connecting disk dynamics to planet formation.

Public lecture by Prof. Didier Queloz, FRS (Jacksonian Professor of Natural Philosophy, Cambridge; Professor of Physics, ETH Zurich), organized by the Swiss Physical Society at EPFL, on how exoplanet discoveries transformed understanding of planet formation and the search for life signatures in planetary atmospheres. Free admission for the general public.

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.

This seminar examines comet impacts during the dispersal of the outer Solar System's planetesimal disk. Instability among the giant planets sent some bodies toward the terrestrial planets. Noble gases preserved in Earth's atmosphere provide evidence for the scale of this bombardment and help relate its timing to the growth of Earth.

This lecture tests whether the Nice model can account for the detailed architecture of the Kuiper belt. It contrasts Neptune's behaviour during planetary instability with simpler gradual-migration scenarios. The distribution of distant small bodies provides constraints on the dynamical history of the giant planets.

When did the giant planets become dynamically unstable? This lecture compares evidence from lunar impact craters, binary objects in the Kuiper belt and dynamical models. It explains why these constraints matter for reconstructing Solar System evolution and why the timing remains an unresolved research question.

This seminar explores a version of the Nice model whose starting planetary configuration is produced by migration through a low-viscosity gas disk. Jupiter and Saturn enter a two-to-one resonance with larger eccentricities than in alternative scenarios. The presentation weighs the strengths and limitations of these initial conditions.

Modern versions of the Nice model connect the initial giant-planet orbits to their earlier migration through a gas disk. This lecture examines resonant chains, possible additional ice giants and the effects of planetesimal interactions. Breaking the chain can trigger instability, with simulations testing which configurations reproduce today's planetary orbits.

The Kuiper belt preserves evidence of major orbital changes among the giant planets. This lecture reviews migration-driven explanations for its resonant, dynamically excited and detached populations. It then examines why these early models required an additional instability mechanism, leading to scenarios involving resonance crossing between Jupiter and Saturn.

This seminar introduces the physical properties of Jupiter's Trojan asteroids and the scientific aims of NASA's Lucy mission. It reviews the mission's planned encounters as described at the time of the talk. It also discusses the 2023 discovery of a binary asteroid whose companion has a contact-binary structure.

This lecture connects the properties of the giant planets to their diverse populations of moons and co-orbiting small bodies. It focuses on irregular satellites, whose inclined and elongated orbits suggest capture, and on Trojan objects that move around stable configurations associated with Jupiter or Neptune.

This lecture traces the origins of different comet populations and the processes that send them into the inner Solar System. It compares the scattered Kuiper-belt reservoir with the distant Oort cloud. It also examines the evidence and debate surrounding a possible additional planet beyond Neptune.

The Kuiper belt contains a complex collection of bodies beyond Neptune, including Pluto. This lecture compares dynamically cold and excited populations, resonant objects, scattered bodies and detached remnants. Their orbital structure provides a record of the Solar System's past evolution.

This lecture follows the growth of planets from an initial population of planetesimals. It examines collisions that build protoplanets, the accretion of smaller particles and mergers between growing bodies. Some sufficiently massive objects also capture surrounding gas, producing different classes of planets.

This lecture examines how dust in a young circumstellar disk becomes large solid bodies. Collective particle motion and its interaction with gas can concentrate material into gravitationally bound clumps. Their collapse offers a route to planetesimals, whose surviving descendants include asteroids and trans-Neptunian objects.

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.

Gas disks around young stars transport material inward while providing the environment for planet formation. This lecture reviews their origin and evolution, including spectroscopic evidence of stellar accretion. It compares viscous-disk models with descriptions that incorporate magnetic fields and the structures they produce.

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.