W.W. Morgan and the Discovery of the Spiral Arms of the Milky Way

  • William Sheehan
  • Christopher J. Conselice


It is now common knowledge that the Milky Way is a vast spiral star system which we view edgewise from just outside one of the spiral arms. Th e first clear demonstration of the fact, by Yerkes Observatory astronomer William Wilson Morgan, occurred only in 1951. Th is was one of the grandest discoveries in the history of astronomy, and when Morgan presented it, in a fifteen minute talk at the American Astronomical Society Society in East Cleveland, Ohio, the day aft er Christmas 1951, he received a resounding ovation, that included not only clapping but stomping of feet. (It was the first time that had happened at an A.A.S. meeting since V.M. Slipher announced the large radial velocities of the spirals in 1914.) But for various reasons—not least that Morgan suff ered a nervous breakdown that led to hospitalization only a few months later—no definitive account of his discovery appeared at the time.1


Globular Cluster Galactic Plane Galactic Structure Double Cluster Personal Notebook 
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  1. 1.
    But see: Anonymous, “Spiral arms of the Galaxy,” Sky and Telescope, April 1952, 138-139; and W.W. Morgan, S. Sharpless and D.E. Osterbrock, “Some features of galactic structure in the neighborhood of the Sun,” Astrophysical Journal, 57 (1952), 3.Google Scholar
  2. 2.
    W.B. Burton, “The morphology of hydrogen and other tracers in the Galaxy,” Annual reviews of Astronomy and Astrophysics, 1976, 275-306.Google Scholar
  3. 3.
    Donald E. Osterbrock. Walter Baade: a life in astrophysics (Princeton, New Jersey: Princeton University Press, 2001), 147Google Scholar
  4. 4.
    Owen Gingerich, “The discovery of the spiral arms of the Milky Way,” in H. van Woerden, R. J. Allen, and W. Butler Burton, eds., The Milky Way Galaxy: proceedings of the 106th symposium of the International Astronomical Union held in Groningen, the Netherlands, 30 May-3 June 1983 (Dordrecht: D. Reidel, 1985), 61.Google Scholar
  5. 5.
    Ken Croswell, The Alchemy of the Heavens: searching for meaning in the Milky Way (New York: Anchor Doubleday, 1995), 75.Google Scholar
  6. 6.
    W. W. Morgan, Personal Notebook No. 242, 1987; contains a short autobiography; Yerkes Observatory Archives.Google Scholar
  7. 7.
  8. 8.
    W. W. Morgan, 1978; Interview with David DeVorkin on August 8. Niels Bohr Library, American Institute of Physics.Google Scholar
  9. 9.
    W.W. Morgan, “A Descriptive Study of the Spectra of the A-type Stars,” Publications of Yerkes Observatory, 7 (1935), 133-250.ADSGoogle Scholar
  10. 10.
    Croswell, Alchemy of the Heavens, 74.Google Scholar
  11. 11.
    Ibid., 78.Google Scholar
  12. 12.
    Sandage, Mount Wilson Observatory, 254.Google Scholar
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    James Kaler, Stars and their Spectra (Cambridge: Cambridge University Press, 2002), 112.Google Scholar
  14. 14.
    W. W. Morgan, Journal, 1942; Yerkes Observatory Archives.Google Scholar
  15. 15.
    W. W. Morgan, Personal Notebook No. 104; Yerkes Observatory Archives.Google Scholar
  16. 16.
    The authoritative biography of Baade is: Donald E. Osterbrock, Walter Baade: a life in astrophysics. Princeton, New Jersey: Princeton University Press, 2001.Google Scholar
  17. 17.
    Walter Baade, “The Resolution of M32, NGC 205, and the Central Region of the Andromeda Galaxy,” Astrophysical Journal, 100 (1944), 137-146.ADSCrossRefGoogle Scholar
  18. 18.
    W. Baade, letter to Jan Oort, September 23, 1946; Jan Oort file, Niels Bohr Library, American Institute of Physics.Google Scholar
  19. 19.
    J. Oort to W. Baade, January 11, 1947; Jan Oort file, Niels Bohr Library, American Institute of Physics.Google Scholar
  20. 20.
    W.W. Morgan to W. Baade, July 12, 1949; Yerkes Observatory Archives.Google Scholar
  21. 21.
    W. Baade to W.W. Morgan, August 20, 1949; Yerkes Observatory Archives.Google Scholar
  22. 22.
    The paper was published as: W.W. Morgan, “Application of the principle of natural groups to the classification of stellar spectra,” Publications of the Observatory of the University of Michigan, 10 (1951), 43-50.Google Scholar
  23. 23.
    DeVorkin interview with Morgan, 1978.Google Scholar
  24. 24.
    The camera and another of its early applications, photography of the gegenschein, are well described in: Otto Struve, “Photography of the Counterglow,” Sky and Telescope, July 1951, 215-218.Google Scholar
  25. 25.
    DeVorkin interview with Morgan, 1978.Google Scholar
  26. 26.
  27. 27.
    Jean’s first husband had been Henry Ware Eliot, brother of T.S.Eliot the poet and cousin of Charles Eliot the president of Harvard University.Google Scholar
  28. 28.
    Morgan, personal notebook no. 230; Yerkes Observatory Archives. Osterbrock was true to his word. He did write Morgan’s biography. See: Donald E. Osterbrock, “William Wilson Morgan, 1906-1994,” Biographical Memoirs of the National Academy of Sciences, 72 (1997), 289-313.Google Scholar
  29. 29.
    W.W. Morgan, personal notebook no. 15, 1956; Yerkes Observatory Archives.Google Scholar

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • William Sheehan
    • 1
  • Christopher J. Conselice
    • 2
  1. 1.WillmarUSA
  2. 2.School of Physics and Astronomy University of NottinghamNottinghamUK

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