Ernst Julius Öpik

Ernst Julius Öpik


Date of Birth
October 23, 1893
Date of Death
September 10, 1985

Born in Estonia, Öpik studied and began research at Moscow University. During World War I he helped establish Turkestan University in Tashkent. In 1921 he returned to Estonia to complete his doctorate and direct astronomy at the University of Tartu. He remained there, aside from four years at Harvard College Observatory, until forced to flee the Red Army by horse cart during World War II. His last four decades of active research were at Armagh Observatory, Northern Ireland, where he edited the Irish Astronomical Journal from 1950 to 1981. During part of this period he also held an appointment at the University of Maryland. Öpik established the foundation of the physical theory of meteors, developed new statistical methods and performed statistical studies of meteors, comets, and asteroids, and predicted the martian craters and the nature of the surface of Venus. He also made early contributions to stellar structure and evolution theory, showing the significance of nonuniform chemical composition in stellar interiors, and explaining the structure of giant stars. Öpik demonstrated that the spiral nebulae were extragalactic as early as 1922. Several of his contributions were not accepted until rediscovered by others much later. Although primarily a theorist, he invented a rocking camera for observations of meteors.

Presentation of Bruce medal

Mercury 5, 4, 25 (1976).

Other awards

American Association for the Advancement of Science & Meteoritical Society, Kepler Gold Medal, 1972
Meteoritical Society, Frederick C. Leonard Medal,1968.
National Academy of Sciences, J. Lawrence Smith Medal, 1960.
Royal Astronomical Society, Gold medal, presented by D.E. Blackwell, QJRAS 16, 358-59 (1975).

Biographical materials

Armagh Observatory, "Ernst Julius Öpik".
Irish Astr. Journal 17, 4, 411-442 (1986). [entire issue, includes 9 articles].
Butler, John, Short Biography of Ernst Julius Öpik
Einasto, Jaan, “Ernst Öpik Centenary,” Mitteilungen der Astronomischen Gesellschaft 77, 19-23 (1994).
Heyden, Francis J., “Some Extra Thoughts on Ernst Julius Öpik," Irish Astr. Journal 19, 2-3 (1989).
Lindsay, E.M., Irish Astr. Journal 10, 1-8 (1972).
O'Connor, J. J. & E. F. Robertson, MacTutor History of Mathematics Archive.
Öpik, E.J., “About Dogma in Science, and Other Recollections of an Astronomer,” Ann. Rev. Astron. & Astrophys. 15, 10 (1977).


Kopal, Zdenek, Astrophys. & Space Sci. 124, 1, 1 (1986).
Moore, Patrick, Sky & Telescope 71, 149 (1986).
Wayman, P.A. & D. J. Mullan, QJRAS 27, 508-12 (1986).
Wetherill, G., Icarus 66, 2, 193-4 (1986).


Armagh Observatory

Named after him

Minor Planet #2099 Opik


Papers, etc.

Papers are at the Armagh Observatory, Armagh, Northern Ireland.

Other References: Historical

Arny, Thomas, “The Star Makers: a History of the Theories of Stellar Structure and Evolution,” Vistas in Astronomy 33, 2, 211-33 (1990).

Bailey, M.E., S. V. M. Clube, & W. M. Napier, The Origin of Comets (Pergamon Press, Oxford, UK, 1990).

Bennett, J.A., Church, State, and Astronomy in Ireland: 200 Years of Armagh Observatory (Armagh Observatory, Armagh in association with the Institute of Irish Studies, the Queen’s University of Belfast, 1990).

Butler, C.J., A Short History of Armagh Observatory

De Groot, Mart, “Armagh Observatory: 200 Years of Irish Excellence,” Astronomy Now 4, 56-58 (1990).

De Groot, Mart, “Ernst Julius Öpik, 1893 - 1985. Reflections on the Life, Works and Personality of Estonia’s Greatest Astronomer.,” International Scientific Conference Devoted to the 200th Anniversary of F.G.W. Struve and J.H. Mädler and the 100th Anniversary of E. J. Öpik, 11-14 (1994).

de Vermond, Mary, “E. Öpik—Composer,” Irish Astr. Jour. Supp. 10, 82-86 (1972).

Eelsalu, Heino, “The Rise and Fall of Small Astronomical Observatories: A Case Study Dorpat/Tartu Observatory,” Journal of Astronomical History & Heritage 2, 111-23 (1999).

Glaessner, M.F., J.H. Shergold & C. Teichert, “Armin Alexander Öpik 1898-1983,” Australian Academy of Science, Biographical Memoirs of Deceased Fellows [brother]

Helin, E.F., “Professor Ernst Opik and his Asteroid 2099 Opik,” Irish Astronomical Journal 17, 428-31 (1986).

“Lembit and His Very Cheeky family,” London Evening Standard 14 April 2007.

McFarland, J. & D. Asher, “The Meteor Work of Ernst Opik at Armagh Observatory,” in D.J. Asher, A.A. Christou, P. Atreya, & G. Barentsen, eds., Proceedings of the International Meteor Conference, Armagh, Northern Ireland, 16-19 September, 2010 (International Meteor Organization, 2011), pp. 67-72.

Muursepp, Peeter & Raimund Preem, “Ernst Öpik and the Perseid Shower,” Sky & Telescope 36, 376 (1968).

Öpik, U. [son], “Reminiscences of Ernst Öpik,” International Scientific Conference Devoted to the 200th Anniversary of F.G.W. Struve and J.H. Mädler and the 100th Anniversary of E. J. Öpik p. 16.

Pustylnik, I., “E. Öpik and the Tartu School of Astrophysics and Stellar Astronomy (1922 - 1945).,” Zvaigžnotā Debess 153, 36-39 (1996).

Pustylnik, I., “Ernst Öpik’s Fundamental Ideas on the Structure of Red Giants,” Astr. Nach. 323, 574-78 (2002).

Sterken, C., “Ernst Julius Öpik, Solar Variability and Climate Change,” Baltic Astronomy 20, 195-203 (2011).

Teerikorpi, P., “On Öpik’s Distance Evaluation Method in a Cosmological Context, ” Astronomy & Astrophysics , 531, id.A10 (2011).

Tsitsin, F.A., “Ehpik i komety — Öpik and Comets,” Istoriko-Astronomicheskie Issledovaniya 29, 128-36, 340 (2004) [in Russian].

Search ADS for works about Öpik

Other References: Scientific

There is a bibliography of Öpik’s publications from 1912-1969 in Irish Astr. Journal 10, 9-22 (1972) and a bibliography from 1972-1985 by J. McFarland in Irish Astr. Journal 17, 441-42 (1986).

Öpik, E., “Zur Theorie der Sonnenstrahlung,” Astron. Nach. 198, 49 (1914).

Öpik, E., “The Densities of Visual Binary Stars,” Ap.J. 44, 292-302 (1916).

Öpik, E., “An Estimate of the Distance of the Andromeda Nebula,” Ap.J. 55, 406-10 (1922).

Öpik, E.J., “Notes on Stellar Statistics and Stellar Evolution,” Tartu Observatory Publications 25, 2 (1922).

Öpik, E.J., “Results of Double-Count Observations of the Perseids in 1921,” Tartu Observatory Publications 25, 4, 3-70 (1923).

Öpik, E.J., “On the Relation of Absolute Magnitude to Colour, Spectrum and Proper Motion,” Tartu Observatory Publications 27, 1 (1929).

Öpik, E.J., “Atomic Collisions and Radiation of Meteors,” Acta Commentationes Univ. Tartu A26, 2, 1-39 (1933).

Öpik, E.J., “Stellar Structure, Source of Energy, and Evolution,” Tartu Observatory Publications 30, 3, 1-115 (1938). [partly reprinted, with commentary, in Lang, Kenneth R. & Owen Gingerich, eds., A Source Book in Astronomy & Astrophysics, 1900-1975 (Harvard Univ. Press, Cambridge, MA, 1979), 342-48]

Öpik, E.J., “Secular Changes of Stellar Structure and the Ice Ages,” MNRAS 110, 49-68 (1950).

Öpik, E.J., “Transport of Heat and Matter by Convection in Stars,” MNRAS 110, 559-89 (1950).

Öpik, Ernst J., “Interstellar Meteors and Related Problems,” Irish Astronomical Journal 1, 80-96 (1950).

Öpik, E., “Stellar Models with Variable Composition. II. Sequences of Models with Energy Generation Proportional to the 15th Power of Temperature,” Proc. R. Irish Acad. A 54, 44-47 (1951).

Öpik, E.J., “Stellar Associations and Supernovae,” Irish Astronomical Journal 2, 219-33 (1953).

Öpik, Ernst J., “The Time-Scale of Our Universe,” Irish Astronomical Journal 3, 89-108 (1954).

Öpik, E.J., “Interplanetary Dust and Terrestrial Accretion of Meteoric Matter,” Irish Astronomical Journal 4, 84 (1956).

Öpik, Ernst Julius, Physics of Meteor Flight in the Atmosphere (Interscience, NY, 1958).

Öpik, Ernst Julius, The Oscillating Universe (Mentor, NY, 1960).

Öpik, E.J., “The Lunar Surface as an Impact Counter,” MNRAS 120, 404 (1960).

Öpik, E.J. & S.F. Singer, “Escape of Gases from the Moon,” Jour. Geophys. Res. 65, 3065-70 (1960).

Öpik, Ernst J., “Tidal Deformations and the Origin of the Moon,” Astronomical Journal 66, 60-67 (1961).

Öpik, E.J. & S.F. Singer, “Density of the Lunar Atmosphere,” Science 133, 1419-20 (1961).

Öpik, E.J., “The Aeolosphere and Atmosphere of Venus,” Jour. Geophys. Res. 66, 2807-19 (1961).

Öpik, E.J. & S.F. Singer, “Density of the Lunar Atmosphere,” Physics of Fluids 4, 221-33 (1961).

Öpik, Ernst Julius, Atmosphere and surface properties of Mars and Venus (North-Holland, Amsterdam, 1962).

Öpik, E.J., “Jupiter: Chemical Composition, Structure, and Origin of a Giant Planet,” Icarus 1, 200-57 (1962).

Öpik, E.J., “The Lunar Atmosphere,” Planetary & Space Sci. 9, 211-44 (1962).

Öpik, E.J., “Climatic Change in Cosmic Perspective,” Icarus 4, 289-307 (1965).

Öpik, Ernst J., “The Martian Surface,” Science 153, 255-65 (1966).

Öpik, Ernst J., “Sun-Grazing Comets and Tidal Disruption,” Irish Astronomical Journal 7, 141-61 (1966).

Öpik, E.J., Mysteries of the Solar System (Oxford U. Press, Oxford, UK, 1968).

Öpik, Ernst J., “Comets and the Formation of Planets,” Astrophys. & Space Sci. 21, 307- 98 (1973).

Öpik, Ernst Julius, Interplanetary Encounters: Close-range Gravitational Interactions (Elsevier, Amsterdam & NY, 1976).

Öpik, Ernst J., “The Moon's Surface,” Ann. Rev. Astron. & Astrophys. 7, 473 (1977).

Öpik, Ernst J., “The Mission Planet,” Moon and the Planets 18, 327-337 (1978).

Valsecchi, Giovanni B., “Close Encounters in Öpik’s Theory,” in Singularities in Gravitational Systems, Lecture Notes in Physics, vol. 590, D. Benest, C. Froeschlé, eds. (Springer, Heidelberg, 2002), pp.145-78.

Search ADS for works by Öpik

Other Works: History, Popularizations, Fiction, etc.

Öpik published hundreds of popular articles in the Irish Astronomical Journal.

Öpik, E., “Meteorites and the Age of the Universe,” Pop. Astron. 41, 71-78 (1933).

Öpik, E.J., “Artificial Satellites,” Irish Astr. Journal 4, 201-51 (1963).

Öpik, E.J., “Astronomical Aspects of the Exploration of Space I,” Irish Astr. Journal 6, 71, 14-28 (1963).

Öpik, E.J., “Dust and Interstellar Absorption,” Irish Astr. Journal 14, 70-72 (1979).

Öpik, Ernst J., “Space Travel and Life Beyond the Earth,” Cosmic Search 3, 2, 2 (1981) and 3, 3, 10 (1981) [reprinted from Irish Astr. Journal 11.

Öpik, Ernst Julius, The Hierarchical Universe (last talk, 1981)

Öpik, E.J., “Kometen—Einfuhrung und Rehabilitation,” Die Sterne 61, 267-69 (1985).