The Bruce Medalists


  Photo 1896, courtesy Mary Lea Shane Archives, Lick Observatory
Frederick Hanley Seares
17 May 1873 1940 Bruce Medalist 20 July 1964

Frederick Seares was born in Michigan and raised in Iowa and southern California. He earned his B.S. at the University of California in 1899, after which he worked as an assistant to Berkeley professor Armin O. Leuschner, from whom he learned to compute orbits and measure stellar positions. From 1899 to 1901 he continued his studies in Paris and Berlin. He taught and investigated comets and variable stars for eight years at the University of Missouri, where Harlow Shapley was his student. He published an important monograph, Practical Astronomy for Engineers in 1909. That year he joined the staff of George E. Hale’s Mt. Wilson Observatory, where he remained for 36 years. There he edited the publications of the observatory’s staff, supervised the Mt. Wilson computers (human, mostly female), and served as assistant director from 1925 until his retirement in 1940. He photographed stars in “selected areas” as part of Jacobus C. Kapteyn’s worldwide effort to determine the structure of the sidereal universe. Using photography Seares standardized the stellar magnitude system and extended it beyond the 18th magnitude. This included calibrating the magnitudes of stars near the North Pole. He used absorbing wire gauze screens and reduced apertures to compare stars of vastly different brightness. He was a pioneer in measuring and interpreting color indices of stars. He also published extensively on the brightness of the Milky Way compared to that of external galaxies and investigated interstellar absorption and reddening of starlight.

Presentation of Bruce medal
Joy, Alfred H., PASP 52, 69-79 (1940).

Some offices held
Astronomical Society of the Pacific, President, 1929.

Biographical materials
Dieke, Sally H., Dictionary of Scientific Biography 12, 264-66.
Huntington Library, Biographical Note accompanying papers
Joy, Alfred H., Biographical Memoirs of the National Academy of Science 39, 417-44
Wilds, Richard P., Biographical Encyclopedia of Astronomers, 2nd ed. (Springer, 2014), pp. 1967-68.

PASP 76, 366-67 (1964).
Redman, R.O., QJRAS 7, 75-79 (1966).
Sky & Telescope 28, 3, 123 (1964).

AIP Center for History of Physics
La Web de la Asociación Larense de Astronomía (painting)
Caltech Archives (with W. Mayer, R.C. Tolman, Einsteins)

Named after him
Lunar crater Seares
Minor Planet #11766 Fredseares

More references

The Bruce Medalists

Please send comments, additions, corrections, and questions to