The Bruce Medalists


  portrait Photo courtesy Prof. Adriaan Blaauw, University of Groningen
Jacobus Cornelius Kapteyn
19 January 1851 1913 Bruce Medalist 18 June 1922

After studies in physics at the University of Utrecht Kapteyn spent three years at the Leiden Observatory. He founded and built the study of astronomy at the University of Groningen from 1878 to 1921. Lacking a telescope, he volunteered to measure photographic plates taken by David Gill at the Cape of Good Hope. From this came a catalog of 454,875 southern stars and values for the density of stars in space as a function of distance, brightness, and spectral class. Kapteyn then organized his Plan of Selected Areas by which astronomers worldwide would determine positions and other data for vast numbers of stars. He compiled tables of distances of stars according to their magnitudes and proper motions and of counts of stars by magnitude and position, and he used these for vast statistical studies. Kapteyn’s model of the sidereal system was valid at high galactic latitudes but failed in the galactic plane because of the lack of knowledge of interstellar absorption. His discovery of “star streaming” led to the finding of galactic rotation. Kapteyn founded the extremely productive “Dutch school” of astronomers.

Presentation of Bruce medal
Curtis, Heber D., PASP 25,15 (1913).

Other awards
Government of Germany, Order Pour le Merite for Arts and Sciences, 1915.
National Academy of Sciences, James Craig Watson Medal, 1913.
Royal Astronomical Society, Gold medal, 1902.

Biographical materials
Blaauw, Adriaan, Dictionary of Scientific Biography 7, 235-40.
Blaauw, Adriaan, Biographical Encyclopedia of Astronomers (Springer, NY, 2007), pp. 611-13.
Hertzsprung-Kapteyn, H., The Life and Works of J.C. Kapteyn (Kluwer, Norwell, MA, 1994) [translation by E.R. Paul of book written by Kapteyn’s daughter in 1928, previously published in Space Science Reviews 64, 1/2, iv-xix, 1-92 (1993)].
Méndez, Javier, Isaac Newton Group of Telescopes
Tenn, Joseph S., “Jacobus Cornelius Kapteyn: The Tenth Bruce Medalist,” Mercury  20, 5, 145 (1991).
University of Groningen
van der Kruit, P.C. & K. van Berkel, eds., The Legacy of J.C. Kapteyn: Studies on Kapteyn and the Development of Modern Astronomy, (Kluwer, Dordrecht & Boston, 2000) [Proceedings of a symposium held in 1999. Table of Contents] [excerpts in Google Books].
van der Kruit, Pieter C., Jacobus Cornelius Kapteyn: Born Investigator of the Heavens (Springer, 2014).
v[an] H[elden], A[lbert], in K.v. Berkel, A.v. Helden, & L. Palm, eds., A History of Science in The Netherlands (Brill, Leiden, 1999), pp. 495-97.
World News site

Crommelin, A.C.D., Nature 110, 48-49 (1922).
Eddington, A.S., Proceedings of the Royal Society of London A 102, no. 719, xxix-xxxv (1923).
Eddington, A.S., Observatory 45, 261-65 (1922).
Jeans, J., MNRAS 83, 250-255 (1923).
Seares, F.H., PASP 34, 233-253 (1922).
van Maanen, A., Ap.J. 56, 145-53 (1922).
van Rhijn, P.J., Popular Astronomy 30, 628-32 (1922).
More obituaries

AIP Center for History of Physics
Observatories of the Carnegie Institution of Washington
University of Groningen
Wikimedia [painting].

Named after him
Lunar crater Kapteyn
Minor Planet #818 Kapteynia
Kapteyn’s Star – the second fastest star known.
Kapteyn Institute, University of Groningen
The Jacobus Kapteyn Telescope
Kapteyn Cottage at Mount Wilson
Kapteyn Series

More references

The Bruce Medalists

Please send comments, additions, corrections, and questions to