The field of exoplanet research owes a significant debt to the work of Swiss astronomer Didier Queloz. Born on , Queloz, along with his colleague Michel Mayor, revolutionized our understanding of planetary systems with the groundbreaking discovery of 51 Pegasi b in 1995 – the first planet found orbiting a Sun-like star. This achievement earned them, along with physicist James Peebles, the Nobel Prize in Physics.
Queloz’s journey began with a strong academic foundation at the University of Geneva, where he earned a Master of Science degree in physics in , followed by a DEA (Diplôme d’Études Approfondies) in Astronomy and Astrophysics in . He continued his studies under the guidance of Michel Mayor, culminating in a PhD in . His doctoral research focused on developing the technology necessary to detect exoplanets by precisely measuring stellar velocities.
The discovery of 51 Pegasi b wasn’t a straightforward process. Mayor secured telescope time in to observe 142 stars similar to our Sun. Queloz began observations in , and by the end of the year, he noticed periodic variations in the light emitted by the star 51 Pegasi. These variations indicated a wobble in the star’s movement, suggesting the presence of an orbiting object. The period of this wobble was remarkably short – just 4.2 days – a timeframe that initially challenged existing theoretical models. As Queloz noted to Mayor, such a short orbital period wasn’t predicted by current understanding.
After rigorous verification, the team confirmed that 51 Pegasi was indeed orbited by an object with roughly half the mass of Jupiter, completing an orbit in just 4.2 days. This discovery, published in the journal Nature, opened up an entirely new field of study – the “revolution of exoplanets” – transforming what was previously a theoretical area of astronomy into a vibrant and rapidly expanding area of research.
Queloz’s work didn’t stop with 51 Pegasi b. He has since been involved in the detection of hundreds of other planets and the measurement of their physical parameters. Notable achievements include the discovery of Gliese 436 b, the first Neptune-sized planet found to transit its star, and the precise measurement of the mass of COROT-7b, confirming the existence of planets with densities similar to rocky planets. These discoveries have contributed significantly to our understanding of the diversity of planetary systems beyond our own.
Currently, Queloz holds the Jacksonian Professorship of Natural Philosophy at the University of Cambridge, and is also a professor of physics at ETH Zurich. He is a fellow of Trinity College, Cambridge, and in , he became a professor at ETH Zurich. In , he was appointed as the founding director of the Center for the Origin and Prevalence of Life at ETH Zurich, signaling a continued focus on the fundamental questions surrounding the possibility of life beyond Earth.
Queloz’s contributions have been widely recognized. He is a member of the Royal Society and received the Wolf Prize in Physics in prior to the Nobel Prize. He was also honored with the National Order of the Legion of Honour in .
The significance of Queloz’s work extends beyond the sheer number of exoplanets discovered. His methods, particularly the radial velocity method (also known as the “wobble method”), provided astronomers with a powerful tool for detecting planets that were previously undetectable. This technique relies on precisely measuring the slight shifts in a star’s spectrum caused by the gravitational pull of an orbiting planet. By analyzing these shifts, astronomers can determine the planet’s mass and orbital period.
Queloz’s research has fundamentally altered our understanding of the universe, demonstrating that planets orbiting other stars are not rare occurrences but are, in fact, commonplace. This realization has fueled the search for habitable planets and the possibility of finding life beyond Earth, marking a pivotal moment in the history of astronomy and our quest to understand our place in the cosmos.
