Jan Hendrik Oort

from Wikipedia, the free encyclopedia
Jan Oort in 1961
Memorial plaque on Oort's birthplace in Franeker

Jan Hendrik Oort (born April 28, 1900 in Franeker , † November 5, 1992 in Leiden ) was a Dutch astronomer .


Oort studied at the University of Groningen . There he was a student of Jacobus C. Kapteyn . From 1924 he worked at the Leiden Observatory . From 1945 to 1970 he was a professor at the University of Leiden . At the same time he was also director of the Leiden observatory .

In 1927, Oort and his colleagues confirmed Bertil Lindblad's hypothesis about the rotation of our galaxy ( Milky Way ), which Immanuel Kant had first proposed in 1755, using Oort's rotation formulas . Oort located the Milky Way center 30,000 light years from Earth in the constellation Sagittarius ( Sagittarius ). He showed that the Milky Way has a mass of 100 billion solar masses .

In the 1950s, Oort postulated an area on the edge of the solar system known as the Oort cloud , from which the comets originate. Oort's theories on this have not yet been confirmed, but are widely accepted.

Oort showed the polarization of the radiation from the Crab Nebula and recognized it as synchrotron radiation .

From 1958 to 1961 Oort was President of the International Astronomical Union .


In 1946 Oort was elected to the American Academy of Arts and Sciences , 1949 to the Royal Society of Edinburgh , 1953 to the National Academy of Sciences and 1957 to the American Philosophical Society . In 1973 Oort was elected a member of the Leopoldina . In 1955 he was elected a corresponding member of the Göttingen Academy of Sciences and was accepted into the Académie des Sciences in Paris.


"De Oortwolk" fountain by Jean-Michel Othoniel in Franeker. The water vapor symbolizes the comets on the edge of our solar system


  • Pieter C. van der Kruit: Jan Hendrik Oort. Master of the Galactic System . Springer Nature, 2019. ISBN 978-3-030-17800-0
  • JK Katgert-Merkelijn: The letters and papers of Jan Hendrik Oort, as archived in the University Library, Leiden . Dordrecht, Kluwer Academic Publishers, 1997. ISBN 0-7923-4542-8

Web links

Individual evidence

  1. Book of Members 1780 – present, Chapter O. (PDF; 289 kB) In: American Academy of Arts and Sciences (amacad.org). Retrieved February 17, 2018 .
  2. ^ Fellows Directory. Biographical Index: Former RSE Fellows 1783–2002. (PDF file) Royal Society of Edinburgh, accessed March 26, 2020 .
  3. Member History: Jan H. Oort. American Philosophical Society, accessed November 2, 2018 .
  4. Holger Krahnke: The members of the Academy of Sciences in Göttingen 1751-2001 (= Treatises of the Academy of Sciences in Göttingen, Philological-Historical Class. Volume 3, Vol. 246 = Treatises of the Academy of Sciences in Göttingen, Mathematical-Physical Class. Episode 3, vol. 50). Vandenhoeck & Ruprecht, Göttingen 2001, ISBN 3-525-82516-1 , p. 182.
  5. ^ List of members since 1666: Letter O. Académie des sciences, accessed on January 29, 2020 (French).