In the years before the Second World War, the Observatory had evolved so little that a competing establishment, the Institut d’astrophysique, was created in 1936 by the Front Populaire. In 1945, André Danjon (1890-1967) was nominated director of the Observatory. He was an energetic and visionary character, who, during his 18-year-long reign, recreated French astronomy and led it in new directions, in particular in radio astronomy and space astronomy.

caption : André Danjon at his astrolabe - credits : Observatoire de Paris