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Detector of extrasolar worlds

Didier Queloz

1966–

Didier Queloz helped make the precise measurements that revealed 51 Pegasi b with Michel Mayor. He then contributed to methods for discovering and characterising many other planets.

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Didier Queloz
Documentary photograph.
L. Weinstein/Ciel et Espace Photos · CC BY 4.0 · Portrait source
Resized and converted to WebP for this site.

A life of research

Born in Switzerland, he undertook doctoral research in Geneva under Michel Mayor. His work included analysing measurements from the ELODIE spectrograph and searching for tiny changes in stellar velocity.

Finding a signal is only the beginning: researchers must establish its repetition and distinguish real stellar motion from instrumental effects or activity on the star itself. Careful checks against these alternatives underpin a reliable discovery.

Understanding the contribution

In 1995 observations of 51 Pegasi revealed a wobble consistent with a nearby giant planet. The radial-velocity method measures the planet's gravitational influence without requiring a direct photograph of the planet.

Queloz subsequently helped expand exoplanet observations through spectroscopy and transit measurements. When a planet crosses in front of its host star, the small reduction in light can reveal information about its size.

What this work changed

The 2019 Nobel Prize in Physics recognised his discovery with Mayor. Their work helped shift the question from whether other planets exist to how varied those planetary worlds can be.

Sources and references