Felix Würsten, ETH Zurich
Twenty-seven years ago, at the University of Geneva, Michel Mayor and Didier Queloz—now a professor at ETH—discovered the first extrasolar planet orbiting a sun-like star. Much has happened since that initial discovery: astronomers have now identified more than 5,000 exoplanets, many of a similar size to Earth, in over 3,700 different planetary systems. With only a tiny portion of the universe analyzed so far, it certainly seems plausible to suggest that life might exist on other planets outside our solar system.
Yet, as any scientist will tell you, a plausible hypothesis is not the same as proof. This has led many researchers to wonder how we might be able to demonstrate the existence of life beyond our solar system. One promising approach is to analyze the atmosphere of exoplanets. By studying the absorption lines in a host star’s optical spectrum, scientists can determine which molecules are present in an exoplanet’s atmosphere, at least in the case of larger planets.