Plenary Lectures and VIP Guests

Dr. Michel Mayor

Abstract:

Are there other Worlds in the universe? Does life exist elsewhere in the cosmos? The technology of our time has made it possible to transform this dream of antiquity into a fascinating field of current astrophysics. 

Thirty years after the discovery of a first planet orbiting a star like our sun, a few thousand planetary systems have been discovered. These first discoveries revealed to us the astonishing diversity of these systems, very different from our solar system: orbital periods of a few hours, planets with very high eccentricity, ocean planets, rocky or gas giant planets with sometimes retrograde orbits, etc. 

The detection and characterization of these planetary systems is the result of various techniques, Doppler spectroscopy, planetary transits, astrometry or gravitational lensing Currently, some of these techniques have the sensitivity required to discover planets with masses smaller than that of our Earth.  The combination of the results of these techniques (mass from Doppler spectroscopy, diameter deduced from the transit) makes it possible to deduce the average density of the planet. This synergy opens the field of comparative planetology. 

After the euphoria of these first discoveries, the era of studying the atmospheres of exoplanets is now beginning. Fascinating, despite the enormous contrast between the luminosity of the star and that of the planet, the analysis of the atmospheres begins and will benefit from space telescopes and giant telescopes on the ground (up to diameter of 39m). 

Does life exist in other places in the cosmos? - Vertiginous question - The analysis of planetary atmospheres may reveal biosignatures, these spectral characteristics induced by the development of life. Advances in spectroscopy studies of exoplanets make us think that the search for extraterrestrial life is possible.

Searches for rocky planets in the habitable zone of their host star reveal objects at distances “relatively close” to our solar system but the humanity will not emigrate to an exoplanet!