 Eberhard Hopf was born in Salzburg, Austria-Hungary, but his scientific career was divided between Germany and the United States.He received his Ph.D. in Mathematics in 1926 and his Habilitation in Mathematical Astronomy from the University of Berlin in 1929.In 1930 he received a fellowship from the Rockefeller Foundation to study classical mechanics with George Birkhoff at Harvard, but his appointment was at the Harvard College Observatory.