The first detection of an exoplanet that opened a new field in planetology

Periodic Radial Velocity oscillations of the star 51 Pegasi measured at OHP (Observatoire de Haute-Provence) in 1995 revealed a planet orbiting around it. This first detection an exoplanet had been expected for long time, since everyone was convinced that most stars were surrounded by planets. success, leading to Nobel Prize physics 2019, is result evolution technics measurement radial velocities during half century OHP.