Family history and educational background; undergraduate degree from University of California Los Angeles (1924-1927); PhD from University of California Berkeley (1927-1931); orbit computing with A. O. Leuschner; thesis work at Lick Observatory with Donald Menzel; work at Harvard College Observatory (1931-1955); with Harlow Shapley, Donald Menzel, Annie Jump Cannon, Antonia Maury, Bart Bok, Leon Campbell, Cecelia Payne Gaposchkin; comets and meteors; radio astronomy; Super Schmidt meteor camera project (1948); Director of the Smithsonian Astrophysical Observatory (1955-1973); science fiction authors, especially Arthur C. Clarke; Moonwatch project, Armand and Grace Spitz; military and science funding; Multi-mirror telescope with A. B. Meinel; "icy comet" model.