Jan Hendrik Oort

Jan Hendrik Oort


Date of Birth
April 28, 1900
Date of Death
November 5, 1992

Jan Oort began studying stellar dynamics under Jacobus C. Kapteyn at the University of Groningen, where he completed his Ph.D. under Pieter van Rhijn in 1926. While a graduate student he spent two years at Yale University with Frank Schlesinger, after which he worked at the University of Leiden from 1924 until his death. In 1927 Oort confirmed Bertil Lindblad’s hypothesis of galactic rotation by analyzing motions of distant stars. Oort found evidence for differential rotation and founded the mathematical theory of galactic structure. During World War II Oort started Hendrik C. van de Hulst on the successful search for a radio spectral line. Following the war Oort led the Dutch group which built a 25-m radio telescope at Dwingeloo and used the 21-cm line to map hydrogen gas in the Galaxy. They found the large-scale spiral structure, the galactic center, and gas cloud motions. In 1950 Oort proposed the now generally accepted model for the origin of comets. He later showed that light from the Crab Nebula is polarized, confirming Iosif S. Shklovskii’s suggestion of synchrotron radiation. He continued researching the Milky Way and other galaxies and their distribution until shortly before his death at 92. Oort was a leader in European astronomy and played a major role in the rise of the European Southern Observatory and other international organizations.

Presentation of Bruce medal

King, Arthur S., PASP 58, 229-32 (1946).

Other awards

American Astronomical Society, Henry Norris Russell Lectureship, 1951.
Association pour le Développement International de l’Observatoire de Nice, ADION medal, 1978
Astronomische Gesellschaft, Karl Schwarzschild Medal, 1972.
Vetlesen Foundation, Vetlesen Prize, 1966.
Inamori Foundation, Kyoto Prize, 1987.
International Balzan Foundation, Balzan Prize, 1984.
National Radio Astronomy Observatory, Jansky Prize, 1967.
Royal Astronomical Society, Gold medal, 1946.

Some offices held

International Astronomical Union, President, 1958-61; General Secretary, 1935-48.

Biographical materials

Blaauw, Adriaan, Biographical Encyclopedia of Astronomers (Springer, NY, 2007), pp. 853-55.
Chapman, David M.F., “Reflections: Jan Hendrik Oort—- Swirling Galaxies and Clouds of Comets,” JRASC 94, 53-54 (2000).
ESA Space Science, “Comet Pioneer: Jan Hendrik Oort,” 27 February 2004.
Oort, J.H., “Some Notes on My Life as an Astronomer,” Annual Reviews of Astronomy & Astrophysics 19, 1 (1981).
Katgert-Merkelijn, J., University of Leiden, Jan Oort, Astronomer
van de Hulst, H.C., Biographical Memoirs of the Royal Society of London 40, 320-26 (1994). van der Kruit, Pieter C., Jan Hendrik Oort: Master of the Galactic System (Springer, 2019). [About this book] .
van Woerden, Hugo, Willem N. Brouw, and Henk C. van de Hulst, eds., Oort and the Universe: A Sketch of Oort’s Research and Person (D. Reidel, Dordrecht, 1980).


Blaauw, Adriaan, Zenit jaarg, 196-210 (1993).
Blaauw, Adriaan & Maarten Schmidt, PASP 105, 681 (1993).
Blaauw, Adriaan, “Oort im Memoriam,” in Leo Blitz & Peter Teuben, eds., 169th IAU Symposium: Unsolved Problems of the Milky Way, (Kluwer Acad. Publishers, 1996), pp. xv-xvi.
Pecker, J.-C., ”La Vie et l’Oeuvre de Jan Hendrik Oort,” Comptes Rendus de l’Acadèmie des Sciences: La Vie des Science 10, 5, 535-540 (1993).
van de Hulst, H.C., QJRAS 35, 237-42 (1994).
van den Bergh, Sidney, “An Astronomical Life: J.H. Oort (1900-1992),” JRASC 87, 73-76 (1993).
Woltjer, L., J. Astrophys. Astron. 14, 3-5 (1993).
Woltjer, Lodewijk, Physics Today 46, 11, 104-05 (1993).


American Institute of Physics Emilio Segr� Visual Archives.
Friedman, Jon R., Portrait Sketch.
University of Leiden: Jan Oort, Astronomer (many).
University of Leiden Observatory (six photos).
Weisstein, Eric W

Named after him

Minor Planet #1691 Oort
Oort Cloud of comets around the Sun.
Oort Constants of galactic structure
J.H. Oort Building, Leiden University


Papers, etc.

Papers are at Leiden University Library. There is a published index: Katgert-Merkelign, J.K., The Manuscripts and Correspondence of Jan Hendrick Oort (University Library, Leiden, 1992). There is an oral history interview at the Niels Bohr Library & Archives.

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).

Blaauw, Adriaan, History of the IAU: The Birth and First Half-century of the International Astronomical Union (Kluwer, Boston, 1994.

Chapman, David M.F., “Jan Hendrik Oort–Swirling Galaxies and Clouds of Comets,” JRASC 94, 53-54 (2000).

Elbers, Astrid, “The Establishment of the New Field of Radio Astronomy in the Post-War Netherlands: A Search for Allies and Funding,” Centaurus 54, 265-285 (2012).

History of Leiden Observatory

National Radio Astronomy Observatory, Prediction of 21cm Line Radiation

Oort, J.H., “The Development of our Insight into the Structure of the Galaxy between 1920 and 1940,” Ann. NY Acad. Sci. 198, 255-66 (1972).

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Other References: Scientific

Oort, J.H., “Some Peculiarities in the Motion of Stars of High Velocity,” Bull. Astron. Inst. Neth. 1, 133-37 (1922).

Oort, J.H., “The Stars of High Velocity,” (Thesis, Groningen University) Publ. Kapteyn Astr. Lab, Groningen, 40, 1-75 (1926).

Oort, Jan H., “Asymmetry in the Distribution of Stellar Velocities,” Observatory 49, 302-04 (1926).

Oort, J.H., “Observational Evidence Confirming Lindblad’s Hypothesis of a Rotation of the Galactic System,” Bull. Astron. Inst. Neth. 3, 275-82 (1927).

Oort, J.H., “Investigations Concerning the Rotational Motion of the Galactic System together with New Determinations of Secular Parallaxes, Precession and Motion of the Equinox (Errata: 4, 94),” Bull. Astron. Inst. Neth. 4, 79-89 (1927).

Oort, J.H., “Dynamics of the Galactic System in the Vicinity of the Sun,” Bull. Astron. Inst. Neth. 4, 269-84 (1928).

Oort, J.H., “Some Problems Concerning the Distribution of Luminosities and Peculiar Velocities of Extragalactic Nebulae,” Bull. Astron. Inst. Neth. 6, 155-59 (1931).

Oort, J.H., “The Force Exerted by the Stellar System in the Direction Perpendicular to the Galactic Plane and Some Related Problems,” Bull. Astron. Inst. Neth. 6, 249-87 (1932).

Oort, J.H., “A Redetermination of the Constant of Precession, the Motion of the Equinox and the Rotation of the Galaxy from Faint Stars Observed at the McCormick Observatory,” 4, 94),” Bull. Astron. Inst. Neth. 8, 149-55 (1937).

Oort, J.H., “Absorption and Density Distribution in the Galactic System,” Bull. Astron. Inst. Neth. 8, 233-64 (1938).

Oort, J.H., “Stellar Motions,” MNRAS 99, 369-84 (1939).

Oort, J.H. “Some Problems Concerning the Structure and Dynamics of the Galactic System and the Elliptical Nebulae NGC 3115 and 4494,” Ap.J. 91, 273-306 (1940).

Mayall, N.U. & J.H. Oort, “Further Data Bearing on the Identification of the Crab Nebula with the Supernova of 1054 A.D. Part II: The Astronomical Aspects,” PASP 54, 95-104 (1942).

Oort, J.H., “Some Phenomena Connected with Interstellar Matter (1946 George Darwin Lecture),” MNRAS 106, 159-79 (1946) [George Darwin Lecture].

Oort, J.H., “The Structure of the Cloud of Comets Surrounding the Solar System and a Hypothesis Concerning its Origin,” Bull. Astron. Inst. Neth. 11, 91-110 (1950).

Oort, J.H., “Origin and Development of Comets (1951 Halley Lecture),” Observatory 71, 129-44 (1951) [Halley Lecture].

Oort, J.H. & M. Schmidt, “Differences between New and Old Comets,” Bull. Astron. Inst. Neth. 11, 259-70 (1951).

Westerhout, G. & J.H. Oort, “A Comparison of the Intensity Distribution of Radio-frequency Radiation with a Model of the Galactic System,” Bull. Astron. Inst. Neth. 11, 323-33 (1951).

Morgan, H.R. & J.H. Oort, “A New Determination of the Precession and the Constants of Galactic Rotation,” Bull. Astron. Inst. Neth. 11, 379-84 (1951).

Oort, J.H. “Problems of Galactic Structure,” Ap.J. 116, 233-250 (1952) [Henry Norris Russell Lecture, 1951].

Oort, J. H., “Outline of a Theory on the Origin and Acceleration of Interstellar Clouds and O Associations,” Bull. Astr. Inst. Neth. 12, 177-86 (1954).

Oort, J. H., & H.C. van de Hulst, “Gas and Smoke in Interstellar Space,” Bull. Astr. Inst. Neth. 10, 187-204 (1946).

van de Hulst, H.C., C.A. Muller, & J.H. Oort, “The spiral structure of the outer part of the Galactic System derived from the hydrogen emission at 21 cm wavelength,” Bull. Astr. Inst. Neth. 12, 117-49 (1954).

van Houten, C.J., J.H. Oort, & W.A. Hiltner, “Photoelectric Measurements of Extragalactic Nebulae,” Ap.J. 120, 439-53 (1954).

Oort, Jan H. & Lyman Spitzer, Jr., “Acceleration of Interstellar Clouds by O-Type Stars,” Ap.J. 121, 6-23 (1955).

Oort, J.H., “Measures of the 21-cm Line Emitted by Interstellar Hydrogen,” Vistas in Astronomy. 1, 607-16 (1955).

Oort, J. H. & Th. Walraven, “Polarization and Composition of the Crab Nebula,” Bull. Astr. Inst. Neth. 12, 285-308 (1956).

Oort, J.H., “Die Spiralstruktur des Milchstraßensystems,” Mitt. Astr. Ges. 7, 83-87 (1956).

Oort, J.H., F.J. Kerr, & G. Westerhout, “The Galactic System as a Spiral Nebula,” MNRAS 118, 379-89 (1958).

Oort, J.H., “Summary - From the Astronomical Point of View,” in Ricerche Astronomiche, Vol. 5, Specola Vaticana, Proceedings of a Conference at Vatican Observatory, Castel Gandolfo, May 20-28, 1957, ed. by D.J.K. O'Connell (North Holland, Amsterdam & Interscience, NY, 1958), 507-29.

Oort, Jan H., “Radio-frequency Studies of Galactic Structure,” Handbuch der Physik vol. 53, 100-28 (1959).

Oort, J.H., “A Summary and Assessment of Current 21-cm Results Concerning Spiral and Disk Structures in Our Galaxy,” in Paris Symposium on Radio Astronomy, IAU Symposium no. 9 and URSI Symposium no. 1, held 30 July - 6 August, 1958, ed. by R.N. Bracewell (Stanford University Press, Stanford, CA, 1959), 409-15

Rougoor, G. W. & J.H. Oort, “Neutral Hydrogen in the Central Part of the Galactic System,” in Paris Symposium on Radio Astronomy, IAU Symposium no. 9 and URSI Symposium no. 1, held 30 July - 6 August, 1958, ed. by R.N. Bracewell (Stanford University Press, Stanford, CA, 1959), pp. 416-22.

Oort, J. H. & G. van Herk, “Structure and dynamics of Messier 3,” Bull. Astr. Inst. Neth. 14, 299-321 (1960).

Oort, J. H., “Note on the Determination of Kz and on the Mass Density Near the Sun,” Bull. Astr. Inst. Neth. 15, 45-53 (1960).

Rougoor, G.W. & J.H. Oort, “Distribution and Motion of Interstellar Hydrogen in the Galactic System with Particular Reference to the Region within 3 Kiloparsecs of the Center,” Proc. Nat. Acad. Sci. 46, 1-13 (1960).

Oort, J.H. & G.W. Rougoor, “The Position of the Galactic Centre,” MNRAS 121, 171-73 (1960).

Oort, J.H., “The Galaxy,” IAU Symposium 20, 1-9 (1964).

Oort, J.H. “Stellar Dynamics,” in A. Blaauw & M. Schmidt, eds., Galactic Structure (Univ. of Chicago Press, Chicago, IL, 1965), pp. 455-512.

Oort, J. H., “Possible Interpretations of the High-Velocity Clouds,” Bull. Astr. Inst. Neth. 18, 421-38 (1966).

Oort, J. H., “Infall of Gas from Intergalactic Space,” Nature 224, 1158-63 (1969).

Oort, J.H., “The Formation of Galaxies and the Origin of the High-Velocity Hydrogen.,” Astronomy & Astrophysics 7, 381-404 (1970).

Oort, J.H., “The Density of the Universe,” Astronomy & Astrophysics 7, 405 (1970).

Oort, J.H., “Galaxies and the Universe,” Science 170, 1363-70 (1970).

van der Kruit, P.C., J.H. Oort, & D.S. Mathewson, “The Radio Emission of NGC 4258 and the Possible Origin of Spiral Structure,” Astronomy & Astrophysics 21, 169-84 (1972).

Oort, Jan H. “On the Problem of the Origin of Spiral Structure,” Mitteilungen der AG 32, 15-31 (1973) [Karl Schwarzschild Lecture, 1972].

Oort, J.H. & L. Plaut, “The Distance to the Galactic Centre Derived from RR Lyrae Variables, the Distribution of these Variables in the Galaxy's Inner Region and Halo, and A Rediscussion of the Galactic Rotation Constants,” Astronomy & Astrophysics 41, 71-86 (1975).

Pels, G., J.H. Oort, & H.A. Pels-Kluyver, “New Members of the Hyades Cluster and a Discussion of its Structure,” Astronomy & Astrophysics 43, 423-41 (1975).

Rubin, Vera C., W. Kent Ford, Jr., Charles J. Peterson, & J.H. Oort,“New Observations of the NGC 1275 Phenomenon,” Ap.J. 211, 693-96 (1977).

Oort, J.H., “The Galactic Center,” Annual Reviews of Astronomy & Astrophysics 15, 295-362 (1977).

Oort, J.H., “Superclusters and Lyman α Absorption Lines in Quasars,” Astronomy & Astrophysics 94, 359-64 (1981).

Oort, J.H., H. Arp, & H. de Ruiter, “Evidence for the Location of Quasars in Superclusters,” Astronomy & Astrophysics 95, 7-13 (1981).

Oort, J.H., “Superclusters,” Annual Reviews of Astronomy & Astrophysics 21, 373-428 (1983).

Oort, J.H., “Structure of the Universe,” in Early Evolution of the Universe and its Present Structure; Proceedings of the Symposium, Kolymbari, Greece, August 30-September 2, 1982, (Reidel, Dordrecht & Boston, 1983), 1-6.

Oort, Jan H. “The Origin and Dissolution of Comets (1986 Halley Lecture),” Observatory 106, 186-93 (1986).

Oort, Jan H. “Origin of Structure in the Universe,” Publ. Astron. Soc. Japan 40, 1-14 (1988).

Oort, J.H., “Questions Concerning the Large-scale Structure of the Universe,” in Problems in Theoretical Physics and Astrophysics: Collection of Articles in Celebration of the 70th Birthday of V. L. Ginzburg (Izdatel’stvo Nauka, Moscow, 1989), pp. 325-337.

Oort, J.H., “Orbital Distribution of Comets,” in W.F. Huebner, ed., Physics and Chemistry of Comets (Springer-Verlag, 1990), pp. 235-44 (1990).

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Other Works: Popularizations, History, etc.

Oort, J.H., “Non-Light-Emitting Matter in the Stellar System,” public lecture of 1926, reprinted in The Legacy of J. C. Kapteyn, ed. by P. C. van der Kruit and K. van Berkel (Kluwer, Dordrecht, 2000) [abstract].

Strom, R. G., G.K. Miley, & J. Oort, “Giant Radio Galaxies,” Sci. Amer. 233, 26 (1975).

Oort, J.H., “A New Southern Hemisphere Observatory,” Sky & Telescope 15, 163 (1956).

Oort, J.H., “Exploring the Nuclei of Galaxies,” Mercury 21, 57 (1992).