Youth plus experience: the discovery of 51 Pegasi b

In 1995, Michel Mayor and Didier Queloz announced they discovered 51 Pegasi b, the first planet ever found around a star other than the Sun. This discovery turned out to be a milestone of recent astronomy, as it opened up a new field of research that is growing impressively these days. However, 51 Pegasi b has surprising properties as compared to the planets of the Solar System, as it is a giant planet on a very close-in orbit around its parent star. Hence, its discovery was unexpected and its actual existence did not go unchallenged. In the following years, a passionate debate sprang up, and finally astronomers accepted it, but at the price of a deep revision of our understanding of how planetary systems are formed and evolve. In the present paper, we reconstruct the dynamics of the discovery of 51 Pegasi b and the first exoplanets, the quarrel that arose among astronomers and the final acceptance of the existence of planets with unexpected characteristics. This remarkable story is recounted by means of published literature as well as interviews with several of its main protagonists.