The Belgian Francqui Prize 2021 awarded to Michaël Gillon

The Belgian Francqui 2021 Prize in Exact Sciences will be awarded to scientist Michaël Gillon (University of Liège) for his pioneering research in exoplanetology and astrobiology. He has designed two robotic telescope networks, TRAPPIST and SPECULOOS, thanks to which he has been able to study exoplanets from Earth with unprecedented precision. He discovered seven potentially habitable planets, which he named “TRAPPIST-1”. He was the first to prove that planets similar in size and mass to Earth do not only orbit the Sun but also ultra-cold stars and that these could harbor life.

The revolutionary nature of his discovery was unanimously recognized by the scientific community, including NASA, inspiring billions of people around the world. The jury – composed of renowned experts and chaired by Professor Ben Feringa, winner of the Nobel Prize in Chemistry in 2016, decided to reward these major discoveries by awarding him the Francqui Prize. The official presentation by His Majesty the King will take place on June 9, 2021 at the Palace of the Academies.

Until 1995, stars were seen as isolated objects. Technological advances have made it possible to establish with certainty the (almost) systematic presence of planets around stars. It is on the basis of these discoveries that Michaël Gillon – a world-renowned scientist specialized in exoplanetology and astrobiology – has developed two robotic telescope networks, TRAPPIST and SPECULOOS, allowing him to observe these exoplanets more closely.

One of his major contributions involves the discovery and detailed observation of the TRAPPIST-1 system of seven exoplanets (located outside the Solar System) orbiting an ultra-cool star and similar to Earth in size and mass. This unprecedented discovery, made in 2016, reinforces the hypothesis that there could be life around a star other than the Sun. It has had considerable scientific and media impact.

Fascinated by the existence of life elsewhere, Michaël Gillon has focused his research on ultra-cool dwarf stars: “As their name suggests, these stars are much smaller and colder than Sun-like stars. They are also much more frequent in the Universe. Our discovery of the TRAPPIST-1 system showed that they could host many Earth-like planets that are sufficiently temperate to potentially have liquid water on their surface and thus allow habitable conditions. Moreover, these are the only stars for which our current technology is capable of studying the atmospheric composition of an Earth-like planet. Perhaps one day we will detect traces of life there! It is for all these reasons that I have focused my research on these miniature stars.”

In order to observe these phenomena more closely, Michaël Gillon and his team of researchers have developed two innovative robotic telescope arrays over several years. The first one, named TRAPPIST, will serve as a prototype for SPECULOOS. These telescopes, placed at different locations on Earth, provide unique conditions for observing exoplanets.

Both of their names refer to the researcher’s origins. “I remember being at the European Observatory of La Silla, in the Atacama Desert in Chile. I was thinking about acronyms that refer to Belgium. That’s how I came up with the idea of “TRAPPIST” (TRAnsiting Planets and Planetesimals Telescope), in reference to one of the most popular Belgian beer categories in the world. The SPECULOOS (Search for Planets EClipsing ULtra-cOOl Stars) project came later, when I wanted to launch a more ambitious project that would focus more on potentially habitable planets.”

TRAPPIST and SPECULOOS offer an unequalled precision of analysis and make it possible to study a series of characteristics inherent to planets thanks to the method of transits. When the planet passes in front of the star, it creates an eclipse and partially hides the star which will then appear slightly less bright. The larger the planet, the more the star will be elided. This method allows to measure the amplitude of the phenomenon and to estimate the size of the planet.

“Via other methods, we also have access to other information such as the mass of the planet, its density or its atmospheric composition…”, adds Mr. Gillon. “The next objective is to study the surface conditions of the planets in order to determine if they are suitable for the existence of liquid water, and therefore of life.

This attraction for extraterrestrial life has fascinated Michaël Gillon since his early childhood. “For as long as I can remember, I have been looking at the stars and wondering if there is life around. I never had fun remembering the names of the constellations, all I was interested in was life.”

And Michaël Gillon added: “I already have international recognition. But the Francqui Prize is particularly symbolic for me because it symbolizes my roots, of which I am proud. I am extremely honored and moved to have received the most prestigious Belgian scientific prize. It is certainly a great moment in my career.”

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