Overview

Didier Queloz (born 23 February 1966) is a Swiss astronomer known for pioneering work in the detection and study of planets beyond the Solar System. He holds academic posts at the University of Geneva and the University of Cambridge and has been associated with collegiate life as a fellow. His research helped transform exoplanet science from a speculative field into a major branch of observational astronomy.

Major discovery and methods

In 1995 Queloz, working with Michel Mayor, announced the detection of 51 Pegasi b, the first confirmed planet orbiting a Sun-like star. That finding, made using the radial-velocity (Doppler) technique, demonstrated that precise measurements of stellar motion could reveal unseen companions. The result sparked intense follow-up work and rapid methodological advances in spectrographs and data analysis.

Queloz's work emphasized precision instrumentation and careful treatment of stellar noise. The radial-velocity approach he used measures tiny shifts in a star's spectrum as an orbiting planet tugs on it; later research combined such measurements with transit observations to determine planet masses, sizes and atmospheric properties.

Career, honours and influence

Queloz has led and collaborated with research groups focused on exoplanet detection and characterization. For his role in opening the field to observational confirmation, he shared the 2019 Nobel Prize in Physics with Michel Mayor; the prize was also awarded that year to Jim Peebles for separate contributions to cosmology. Beyond the Nobel, Queloz's career includes numerous scientific awards, invited lectures and mentorship of younger astronomers.

Contributions and legacy

  • Co-discovery of the first exoplanet orbiting a Sun-like star, establishing new observational techniques.
  • Advances in high-precision radial-velocity measurements and interpretation of stellar signals.
  • Integration of radial-velocity and transit methods to characterize exoplanet properties.
  • Influence on the development of instruments and space missions dedicated to exoplanet studies.

Queloz's discovery reshaped questions about planet formation, frequency of planetary systems and the search for potentially habitable worlds. His ongoing work and the technologies his field inspired continue to expand our knowledge of planetary systems beyond the Solar System.