Ce portail offre des connaissances de base sur le thème de l'astronomie et présente les travaux et coopérations de recherche actuels en Suisse.

Immagine: ESO

Exoplanets

One known exoplanetary system is Trappist-1,  consisting of planets orbiting a red dwarf at a distance of 40 light years.
One known exoplanetary system is Trappist-1, consisting of planets orbiting a red dwarf at a distance of 40 light years.Immagine: NASA/JPL-Caltech

Planets also exist outside our Solar System. Astronomers call them "extrasolar planets", or exoplanets for short. People have known for many hundreds of years that suns other than our own exist. But it was not until 1992 that Aleksander Wolszczan and Dale Frail discovered the first planet to exist outside our Solar System. The first planet orbiting a sun-like star was discovered by Michael Mayor and Didier Queloz from the University of Geneva in 1995: 51 Pegasi b. Today, almost 5000 exoplanets are known and catalogued. Among them is WASP 39b, which orbits a star in the constellation of Virgo. It was discovered in 2011 using the transit method and orbits its star in just four days. Thanks to the James Webb Space Telescope (JWST), it will be intensively analysed over the next few years.

Astronomers suspect that there are exoplanets that are home to living creatures. To be able to guess whether life is even possible on an exoplanet, researchers need to know whether it is in the habitable zone. This is the distance from its star in which water is constantly present in liquid form. Liquid water is an essential prerequisite for life similar to that on Earth. The type of star also plays a role. Accordingly, the planet is subjected to excessive radiation, or its orbit is impaired. Researchers are also investigating the atmosphere of exoplanets in order to draw conclusions regarding possible life. Free oxygen would be an important indicator. At the moment, the Earth's atmosphere is still the only one known to contain oxygen in a free form.

The CHEOPS satellite collects data on exoplanets in space - but it was still on Earth here
The CHEOPS satellite collects data on exoplanets in space - but it was still on Earth hereImmagine: ESA/S. Corvaja