Jean Picard, a priest, an astronomer and a geodesist, aged 49, has measured an arc of meridian between Paris and Amiens, hence the radius and the circumference of the earth by extrapolation. He is a pupil of Astronomer Pierre Gassendi (†1655), who was also a priest and a philosopher, and as of 1623 a promoter of heliocentricism, ten years before the sentence against Galileo Galilei (†1642). Picard is also one of the 21 first members of the Académie Royale des Sciences  founde