Fr. Johan Stein, S.J.
Fr. Johan Stein S.J. (1871-1951) served as Director of the Vatican Observatory from 1930 to 1951. He oversaw a modernization of the Observatory and also its relocation to Castel Gandolfo in the 1930s. The crater Stein on the far side of the moon is named for him. His comprehensive book on variable stars, Die Veränderlichen Sterne, was considered for many years a classic in this field.