Willem de Sitter

Willem de Sitter


Date of Birth
May 6, 1872
Date of Death
November 20, 1934

Willem de Sitter studied mathematics at the University of Groningen, where a chance meeting with David Gill led to an invitation to work at Her Majesty’s Observatory at the Cape of Good Hope. After four years of heliometer measurements of stars and especially Jupiter’s Galilean satellites, de Sitter returned to the Netherlands and became a mathematical astronomer, earning his doctorate under J.C. Kapteyn with a thesis on the satellites’ motions. He spent most of his career at the University of Leiden, where he directed and expanded the astronomy program. He continued to work extensively on the motions of the satellites of Jupiter, determining their masses and orbits from decades of observations. He redetermined the fundamental constants of astronomy and determined the variation of the rotation of the earth. He also performed statistical studies of the distribution and motions of stars, but today he is best known for his contributions to cosmology. Since Holland remained neutral in World War I, de Sitter was able to be the liaison between scientists in warring countries, notably A.S Eddington in Britain and Albert Einstein in Germany. De Sitter’s 1917 solution to Einstein’s field equations showed that a near-empty universe would expand. Later, he and Einstein found an expanding universe solution without space curvature.

Presentation of Bruce medal

Meyer, W.F., PASP 43, 125-129 (1931).

Other awards

National Academy of Sciences, James Craig Watson Medal, 1929.
Royal Astronomical Society, Gold medal, 1931, awarded by A.C.D. Crommelin, MNRAS 91, 422-34 (1931).

Some offices held

International Astronomical Union, President, 1925-28.

Biographical materials

Blaauw, A.Dictionary of Scientific Biography 12, 448-50.
Blaauw, A.Biographical Encyclopedia of Astronomers (Springer, NY, 2007), pp. 1063-64.
Club Astronomique du Val de Loir [in French].
De Sitter-Suermondt, Eleonora [wife], Willem de Sitter, een Mensenleven (Tjeenk Willink & Zoon, Haarlem, 1948) [in Dutch].
Díaz Pazos, Patricio T., AstroCosmo [in Spanish].
McCrea, W.H., J. Brit. Astr. Ass. 82, 178-181 (1972).
Tenn, Joseph S., “Willem de Sitter: The Twenty-Sixth Bruce Medalist,” Mercury 23, 5, 28 (1994).
O’Connor, J.J. & E.F. Robertson, University of St. Andrews, The MacTutor History of Mathematics archive.
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. 558-60.


Chant, C.A., JRASC 29, 1 (1935).
Hins, C.H., Hemel en Dampkring 33, 1-18 (1935) [in Dutch].
Oort, J.H., Observatory 58, 22-27 (1935).
S[pencer] J[ones], H[arold]MNRAS 95, 343-347 (1935).
New York Times editorial, 25 Nov 1934 [reprinted in PASP 47, 65-66 (1935)]
More obituaries


AIP Center for History of Physics, especially this photo from around 1898.
AstroCosmo (sketch)
Johan Hidding, University of Groningen
Instituut voor Nederlandse Geschiedenis (with biography in Dutch)

Named after him

Lunar crater De Sitter
Minor Planet #1686 De Sitter
de Sitter space


Papers, etc.

De Sitter’s papers are at the Leiden University Library. There is much correspondence with de Sitter in the Albert Einstein papers.

Other References: Historical

Baneke, David, “Teach and Travel: Leiden Observatory and the Renaissance of Dutch Astronomy in the Interwar Years” Journal for the History of Astronomy 41, 167-98 (2010).

Berger, A., ed., The Big Bang and Georges Lemaître: Proceedings of a Symposium in Honour of G. Lemaître Fifty Years after his Initiation of Big-Bang Cosmology, Louvainla-Neuve, Belgium, 10-13 October 1983 (D. Reidel Pub. Co., Sold and distributed in the U.S.A. and Canada by Kluwer Academic Publishers, 1984).

de Sitter, Willem, Short History of the Observatory of the University at Leiden, 1633-1933 (J. Enschedé, Haarlem, 1933). 48 p.

de Sitter, Wolter Reinold, “Kapteyn and de Sitter; a Rare and Special Teacher-Student and Coach-Player Relationship,” in Invited Reviews Presented at the Symposium “The Legacy of J. C. Kapteyn”, Groningen, The Netherlands, June 9-11, 1999, ed. by P. C. van der Kruit and K. van Berkel (Kluwer Academic Publishers, Dordrecht, 2000), pp. 79 - 108 [abstract].

Douglas, A. Vibert, “Determination of the Curvature Invariant of Spacetime, ” Science 59, 311-12 (1924).

Ellis, George F.R., “The Expanding Universe: A History of Cosmology from 1917 to 1960,” in Einstein and the History of General Relativity, ed. by Don Howard & John Stachel, Proceedings of the 1986 Osgood Hill Conference, North Andover, MA, Einstein Studies, v. 1 (Birkhäuser, Boston, 1988), pp. 367-432.

Godart, Odon and M. Heller, Cosmology of Lemaître (Pachart Pub. House, Tucson, c1985).

Hetherington, Norriss S., “The Measurement of Radial Velocities of Spiral Nebulae,” Isis 62, 309-13 (1971).

Hetherington, Norriss S., “Theoretical Cosmology in the Twentieth Century,” Human Implications of Scientific Advance, Eric Gray Forbes, ed., Proceedings of the 15th International Congress of the History of Science in Edinburgh 10-15 Aug 1977 (Edinburgh U.P., Edinburgh, 1978), p. 567-75.

Hoskin, M.A. & G.J. Whitrow, Introduction to Symposium 10 [Cosmology Since Newton], Theoretical Cosmology in the Twentieth Century, Human Implications of Scientific Advance, Eric Gray Forbes, ed., Proceedings of the 15th International Congress of the History of Science in Edinburgh 10-15 Aug 1977 (Edinburgh U.P., Edinburgh, 1978), p. 541-43.

Jahn, Carla & Franz Kahn, “Letters from Einstein to de Sitter on the nature of the Universe,” Nature 257, 451-454 (1975).

Janssen, Michael, “The Einstein-De Sitter Debate and Its Aftermath”

Kerszberg, Pierre, “Einstein, De Sitter and Cosmology,” in Einstein and the History of General Relativity, ed. by Don Howard & John Stachel, Proceedings of the 1986 Osgood Hill Conference, North Andover, MA, Einstein Studies, v. 1 (Birkhäuser, Boston, 1989), pp. 325-366.

Kerszberg, Pierre, The Invented Universe: The Einstein-de Sitter Controversy (1916-17) and the Rise of Relativistic Cosmology (Clarendon Press, Oxford, 1989).

Munitz, Milton K., ed., Theories of the Universe: from Babylonian Myth to Modern Science (Free Press, Macmillan, 1957)

North, J.D., The Measure of the Universe: A History of Modern Cosmology (Oxford Univ. Press, Oxford, 1965; Dover, 1990).

Röhle, Stefan, Willem de Sitter in Leiden - ein Kapitel in der Rezeptionsgeschichte der Relativitätstheorien (Johannes Gutenberg Universität Mainz, Mainz, 2007).

Whitrow, G.J., “Theoretical Cosmology in the Twentieth Century,” in Human Implications of Scientific Advance, Eric Gray Forbes, ed., Proceedings of the 15th International Congress of the History of Science in Edinburgh 10-15 Aug 1977 (Edinburgh U.P., Edinburgh, 1978), p. 576-93.

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Other References: Scientific

Many papers of de Sitter may be found at the site of the Royal Netherlands Academy of Arts and Sciences: http://www.dwc.knaw.nl/toegangen/digital-library-knaw/.

de Sitter, W., “On the Use of the Electric Light for the Artificial Star of the Zöllner Photometer,” MNRAS 59, 341 (1899).

de Sitter, W., “On the Systematic Difference, Depending on Galactic Latitude, between the Photographic and Visual Magnitudes of the Stars,” Publications of the Kapteyn Astronomical Laboratory Groningen , 2, 5-22 (1900) [prefatory note by J.C. Kapteyn].

de Sitter, W., “The Orbits of Jupiter’s Satellites,” Observatory 24, 341-45 (1901).

de Sitter, W., “The Determination of Jupiter’s Mass from the Cape Observations,” Observatory 25, 50-54 (1902).

de Sitter, W., “On Periodic Orbits of the Type Hestia,” KNAW, Proceedings 10 I, 47-56 (1907).

de Sitter, W., “On Some Points in the Theory of Jupiter’s Satellites,” Proc. Royal Acad. Amsterdam [KNAW] 10 I, 95-107 (1907).

de Sitter, W., “On the Masses and Elements of Jupiter’s Satellites, and the Mass of the System,” Proc. Royal Acad. Amsterdam [KNAW] 10 II, 653-73 (1908) and 10 II, 710-29 (1908).

Donner, Anders, J.C. Kapteyn, & W. de Sitter, “The Parallaxes of 3650 Stars of Different Galactic Latitudes, Derived from Photographic Plates,” Publications of the Kapteyn Astronomical Laboratory Groningen 20, 1-T136 (1908).

Gill, David, W.H. Finlay, W. de Sitter, & V.A. Lowinger, “Researches on Stellar Parallax Made with the Cape Heliometer,” Annals Cape Obs 8, 2.i-2.175 (1909).

de Sitter, W., “On the Periodic Solutions of a Special Case of the Problem of Four Bodies” Proc. Royal Acad. Amsterdam [KNAW] 11 II, 682-98 (1909).

de Sitter, W., “On the Formulae for the Comparison of Observed Phenomena of Jupiter’s Satellites with Theory,” MNRAS 71, 85-101 (1910).

de Sitter, W., “On the Bearing of the Principle of Relativity on Gravitational Astronomy,” MNRAS 71, 388-415 (1910)

de Sitter, W., “Absorption of Gravitation,” Observatory 35, 387-93 (1912).

de Sitter, W., On Absorption of Gravitation and the Moon’s Longitude. Part I, Proc. Royal Acad. Amsterdam [KNAW]15 II, 808-824 (1912-1913) and 15 II, 824-39 (1912-13).

de Sitter, W., “Some Problems of Astronomy. VII The Secular Variation of the Elements of the Four Inner Planets,” Observatory 36, 296-303 (1913).

de Sitter, W., “Ein astronomischer Beweis für die Konstanz der Lichgeshwindigkeit,” Physik. Zeitschr. 14, 429 (1913). Translated by Robert Fritzius as “An Astronomical Proof for the Constancy of the Speed of Light”.

de Sitter, W., “Über die Genauigkeit, innerhalb welcher die Unabhängigkeit der Lichgeschwindigkeit von der Bewung der Quelle behauptet werden kann,” Physik. Zeitschr. 14, 1267 (1913). Translated by Robert Fritzius as “About the Accuracy within Which the Independence of the Speed of Light from the Movement of the Source Can Be Stated”.

Gill, Sir David & W.H. Finlay, Determination 0f the Mass of Jupiter and Elements of the Orbits of its Satellites from Observations Made with the Cape Heliometer, reduced and discussed by W. de Sitter (H.M. Stationery Off., Edinburgh, 1915).

de Sitter, Willem, “Proposal for a New Method of Determining the Constant of Aberration,” MNRAS 75, 458-64 (1915).

de Sitter, Willem, “The Figure of the Earth,” Observatory 38, 397-98 (1915).

de Sitter, Willem, “The Longitude of Jupiter’s Satellites, derived from Photographic Plates taken at the Cape Observatory in the Year 1913,” MNRAS 76, 448-68 (1916) .

de Sitter, W., “Space, Time, and Gravitation,” Observatory 39, 412-19 (1916).

de Sitter, W., “The Motion of the Perihelion on the Classical Theory of Relativity,” Observatory 40, 302-03 (1917).

de Sitter, W., “On the Relativity of Inertia. Remarks Concerning Einstein’s Latest Hypothesis,” Proc. Royal Acad. Amsterdam [KNAW] 19, 1217-25 (1917).

de Sitter, Willem, “Further Remarks on the Solutions of the Field-Equations of Einstein’s Theory of Gravitation, Proc. Royal Acad. Amsterdam [KNAW] 20 II, 1309-12 (1918).

de Sitter, Willem, “A. Einstein’s Theory of Gravitation and its Astronomical Consequences,” MNRAS 76, 699-728 (1916)77, 155-83 (1916)78, 3-28 (1917).

de Sitter, Willem, “On the Einstein Terms in the Motion of the Lunar Perigee and Node,” MNRAS 81, 102 (1920).

de Sitter, W., “On the Most Probable Values of Some Astronomical Constants, First Paper, Constants Connected with the Earth,” Bull. Astron. Netherlands 4, 57-61 (1930).

de Sitter, Willem, “De seculaire acceleraties en de fluctuaties in de lengtes van de maan, de zon, Venus en Mercurius, en de rotatie der aarde,” Proc. Royal Acad. Amsterdam [KNAW] 36 I, 451-64) (1927) [in Dutch].

Alden, H.L., W. de Sitter, & G. Pels, “The Longitudes of Jupiter’s Satellites Derived from Plates Taken with the 26-inch Telescope of the Yale Observatory Southern Station,” Bull. Astron. Netherlands 5, 55-60 (1929) and 5, 121-24 (1929).

de Sitter, W., “On the Distances and Radial Velocities of Extra-Galactic Nebulae, and the Explanation of the Latter by the Relativity Theory of Inertia,” Proceedings of the National Academy of Sciences 16, 474-88 (1930).

de Sitter, W., “On the Magnitudes, Diameters and Distances of the Extragalactic Nebulae and Their Apparent Radial Velocities,” Bull. Astron. Netherlands 5, 157-171A (1930).

de Sitter, W., “The Expanding Universe. Discussion of Lemaître’s Solution of the Equations of the Inertial Field,” Bull. Astron. Netherlands 5, 211-18 (1930).

de Sitter, W., “Further Remarks on the Astronomical Consequences of the Theory of the Expanding Universe,” Bull. Astron. Netherlands 5, 274-76 (1930).

de Sitter, Willem, “Jupiter’s Galilean Satellites,” George Darwin Lecture, MNRAS 91, 706-38 (1931).

de Sitter, W., “Some Further Computations Regarding Nonstatic Universes,” Bull. Astron. Netherlands 6, 141-45 (1931).

de Sitter, W., “Do the galaxies expand with the universe?” Bull. Astron. Netherlands 6, 146 (1931).

de Sitter, Willem, Kosmos: A Course of Six Lectures on the Development of our Insight into the Structure of the Universe, delivered for the Lowell Institute in Boston, in November 1931 (Harvard Univ. Press, 1932)

Einstein, A. & W. de Sitter, “On the Relation between the Expansion and the Mean Density of the Universe,” Proceedings of the National Academy of Sciences 18, 213 (1932). [reprinted, with commentary, in Lang, Kenneth R. & Owen Gingerich, eds., A Source Book in Astronomy & Astrophysics, 1900-1975 (Harvard Univ. Press, 1979), 849-50.]

de Sitter, Willem “On the Expanding Universe,” KNAW, Proceedings 35 I, 596 -607 (1932).

de Sitter, Willem, “The Astronomical Aspect of the Theory of Relativity”, University of California Publications in Mathematics 2, 8, 143-196 (1933). [Hitchcock lecture, 1933].

de Sitter, Willem, “On the Expanding Universe and the Time-scale,” MNRAS 93, 628-34 (1933).

de Sitter, W., “On the Motion and the Mutual Perturbations of Material Particles in an Expanding Universe,” Bull. Astron. Netherlands 7, 97-105 (1933).

de Sitter, W., “On Distance, Magnitude, and Related Quantities in an Expanding Universe,” Bull. Astron. Netherlands 7, 205-16 (1934).

de Sitter, Willem “On the Foundations of the Theory of Relativity, with Special Reference to the Theory of the Expanding Universe,” Proc. Royal Acad. Amsterdam [KNAW] 37 I, 597-601 (1934).

de Sitter, W., “On the System of Astronomical Constants (edited and completed by Dirk Brouwer) [Errata: 10, 146], Bull. Astron. Netherlands 8, 213-31 (1938).

Eddington, A.S., The Expanding Universe, Royal Institution Library of Science: Astronomy, p. 305-13.

Milne, E.A.Relativity, Gravitation and World Structure (Oxford U.P., 1935).

Robertson, H. P., “Relativistic Cosmology,” Rev. Mod. Phys. 5, 62-90 (1933).

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Other Works: Popularizations, Fiction, etc.

de Sitter, Willem, “The Size of the Universe,” PASP 44, 89-104 (1932).