Beyond the Big Galaxy: The Structure of the Stellar System 1900–1952

Herschel J. F. W. , Outlines of astronomy (London, 1849), 531.

Herschel W. , ‘On the construction of the heavens’, Philosophical transactions , lxxv (1785), 213–66. For a review of ‘The Milky Way from Antiquity to modern times’, see Hoskin's M. A. paper, pp. 11–24 in The Milky Way Galaxy: Proceedings of the 106^th Symposium of the International Astronomical Union held in Groningen, the Netherlands, 30 May — 3 June, 1983 (Dordrecht, 1985), ed. by Van Woerden H. Allen R. J. Burton W. B. Jaki's S. L. The Milky Way: An elusive road for science (New York, 1972) is also a rich if militantly whiggish account.

Herschel J. F. W. , Outlines of astronomy (ref. 1), 529. For a later version of the ring theory see Proctor R. A. , ‘A new theory of the Milky Way’, Monthly notices of the Royal Astronomical Society , xxx (1870), 50–56.

Struve F. G. W. , Études d'astronomie stellaire sur la voie lactée et sur la distance des étoiles fixes (St Petersburg, 1847).

Kragh H. Smith R. W. , ‘Who discovered the expanding universe?’, History of science , xli (2003), 141–62, p. 142.

Newcomb S. , Sidelights on astronomy and kindred fields of popular science (New York and London, 1906), 53.

Dewhirst D. W. Hoskin M. , ‘The Rosse spirals’, Journal for the history of astronomy , xxii (1991), 257–66, Hoskin M. , ‘The Leviathan of Parsonstown: Ambitions and achievements’, Journal for the history of astronomy , xxxiii (2002), 57–70, and Schaffer S. , ‘The Leviathan of Parsonstown: Literary technology and scientific reputation’, in Inscribing science: Scientific texts and the materiality of communication , ed. by Lenoir T. (Stanford, 1998), 182–222.

Alexander S. , ‘On the origin of the forms and the present condition of some of the clusters of stars, and several of the nebulae’, Astronomical journal , ii (1852), 95–96, 97–103, 105–11, 113–15, 126–8, 140–2, 148–52, 158–60, p. 101.

In 1903, Kapteyn J. C. arranged for Easton to be awarded an honorary degree from the University of Groningen for his scientific contributions.

Easton C. , ‘A new theory of the Milky Way’, Astrophysical journal , xii (1900), 136–58.

Easton , ‘A new theory of the Milky Way’, 157. On Keeler and his researches, see Osterbrock Donald , James E. Keeler: Pioneer American astrophysicist and the early development of American astrophysics (Cambridge, 1984).

Easton , ‘A new theory of the Milky Way’, 157.

Easton C. , ‘A photographic chart of the Milky Way and the spiral structure of the galactic system’, Astrophysical journal , xxxvii (1913), 105–18.

Smith R. W. , The expanding universe: Astronomy's ‘Great Debate’ 1900–1931 (Cambridge, 1982), chap. 1.

See, for example, Gill D. Hale G. , 13 December 1909, Gill Papers, Royal Astronomical Society Archives.

Pannekoek A. , The history of astronomy (London, 1961), 473.

Holmberg G. , Reaching for the stars: Studies in the history of Swedish stellar and nebular astronomy 1860–1940 (Lund, 1999), 132.

Charlier C. , Studies in stellar statistics : *1. Constitution of the Milky Way. First memoir (Lund, 1912). On Charlier and his various researches, see Holmberg's Reaching for the stars (ref. 17). On the development of statistical studies of the Galaxy, see Paul E. R. , The Milky Way and statistical cosmology 1890–1924 (New York, 1993).

Obituary of Seeliger by Eddington A. S. , Monthly notices of the Royal Astronomical Society , lxxxv (1925), 316–18, p. 316.

See Paul E. R. , ‘The death of a research programme: Kapteyn and the Dutch astronomical community’, Journal for the history of astronomy , xii (1981), 77–94. For an example of the heroic status enjoyed by Kapteyn among Dutch astronomers after his death, see, for example, de Sitter's W. Kosmos (Cambridge, MA, 1932). The book contains portraits of seven scientists: William Herschel Copernicus Brahe Kepler Galileo Newton Kapteyn .

Paul , The Milky Way and statistical cosmology (ref. 18), 55.

Eddington A. S. , Stellar movements and the structure of the universe (London, 1914), 184.

Seeliger H. , Abhandlungen der Mathematisch-Physikalischer Klasse der K. Bayerischen Akademie der Wissenschaften zu München , xix (1898), 565–629.

Smith R. W. , ‘Kapteyn and cosmology’, The legacy of J. C. Kapeyn: Studies on Kapteyn and the development of modern astronomy , ed. by Van Der Kruit P. C. Van Berkel K. (Dordrecht, 2000), 175–90, p. 182.

On Seeliger's investigations, see Paul , The Milky Way and statistical cosmology (ref. 18), chap. 3. On the wider cosmological issues that were also in play for Seeliger, see also North J. D. , The measure of the universe (Oxford, 1965), 16–18.

Sitter De , Kosmos (ref. 20), 57.

Eddington , Stellar movements (ref. 22), 184. On the paucity of parallax data, see also, for example, S. Newcomb, The stars: A study of the universe (London, 1908). Also useful is A. Nielsen, ‘Contributions to the history of the Hertzsprung-Russell diagram’, Centaurus , ix (1963), 219–53, pp. 223–5.

Seares F. H. , ‘J. C. Kapteyn’, Publications of the Astronomical Society of the Pacific , xxxiv (1922), 233–53, p. 234.

Sullivan W. T. III , ‘Kapteyn and twentieth century Dutch astronomy’, in The legacy of J. C. Kapteyn: Studies on Kapteyn and the development of modern astronomy , ed. by Van Der Kruit P. C. Van Berkel K. (Dordrecht, 2000), 229–64, p. 236.

Paul , The Milky Way and statistical cosmology (ref. 18), 84.

Kapteyn J. C. , The plan of selected areas (Groningen, 1906).

For a progress report from 1914 by Kapteyn , see ‘The ‘Plan of Selected Areas'’, Monthly notices of the Royal Astronomical Society , lxx (1914), 348–52.

DeVorkin D. , ‘Stellar evolution and the origin of the Hertzsprung-Russell diagram’, in The general history of astronomy , iv: Astrophysics and twentieth century astronomy to 1950 , Part A (Cambridge, 1984), ed. by Gingerich O. , 90–108, p. 96.

Kobold H. , ‘Untersuchungen der Eigenbewegung des Auwers-Bradley Catalogs nach der Bessel'schen Methode’, Abhandlungen der Kaiserlicher Leopoldinisch-Carolinischen Deutschen Akademie der Naturforscher , lxiv (1895), 213–365. See also Paul , The Milky Way and statistical cosmology (ref. 18), 86. Kobold later authored a notable textbook on stellar astronomy, Der Bau des Fixsternsystems, mit besonderer Berücksichtgung der photometrischen Resultate (Braunschweig, 1906).

Paul , The Milky Way and statistical cosmology (ref. 18), 47.

Kapteyn J. C. , ‘Star streaming’, Report of the British Association for the Advancement of Science, Section A (1905), 257–65, p. 264. See also Kapteyn J. C. , ‘On the structure of the universe’, Scientia , xiv (1913), 345–57.

Eddington A. , ‘The systematic motion of the stars’, Monthly notices of the Royal Astronomical Society , lxvii (1906), 34–63.

Dreyer J. L. E. as quoted in Douglas Vibert A. , Arthur Stanley Eddington (London, 1956), 20.

See Paul , The Milky Way and statistical cosmology (ref. 18) for a fuller account, especially pp. 84–94 and 126–36.

Kapteyn J. C. , ‘On the absorption of light in space’, Astrophysical journal , xxix (1909), 46–54, p. 46.

Kapteyn , ‘On the absorption of light in space’, 46. See also Kapteyn J. C. , ‘Remarks on the determination of the number and mean parallax of stars of different magnitude and the absorption of light in space’, Astronomical journal , xxiv (1904), 115–23.

Kapteyn J. C. , ‘On the absorption of light in space’, Astrophysical journal , xxx (1909), 284–317.

This point is discussed in Seeley D. , ‘The development of research on the interstellar medium c. 1900–1940: Diffuse nebulae, interstellar gas, and interstellar extinction’, unpublished Ph.D. thesis, Boston University Graduate School, 1973, 229–30. See, for example, Kapteyn's comments in his letter to Hale G. E. , 23 September 1915, G. E. Hale Papers, Microfilm Edition.

For an excellent biography of Barnard, see Sheehan W. , The immortal fire within: The life and work of Edward Emerson Barnard (Cambridge, 1995). For Barnard's researches on the Milky Way, see especially chapters 16 and 20.

This point is made by Berendzen R. Hart R. Seeley D. , Man discovers the galaxies (New York, 1984), 71, based on their reading of Barnard E. E. , “On a nebulous groundwork in the constellation Taurus”, Astrophysical journal , xxv (1907), 218–25.

Barnard E. E. , ‘On a nebulous region and on the question of absorbing matter in space and the transparency of nebulae’, Astrophysical journal , xxxi (1910), 8–14, p. 13.

Barnard E. E. , ‘On the dark markings of the sky with a catalogue of 182 such objects’, Astrophysical journal , xlix (1919), 1–23, p. 1.

Shapley H. , ‘Studies based on the colors and magnitudes in stellar clusters. Second Paper: Thirteen hundred stars in the Hercules Cluster (Messier 13)’, Contributions from the Mount Wilson Solar Observatory , no. 116 (1915), 52.

Kapteyn J. C. Shapley H. , 17 August 1915, Shapley Papers, Harvard University Archives.

Kapteyn , ‘On the absorption of light in space’ (ref. 42), 56.

Slipher V. M. , ‘Peculiar star spectra suggestive of selective absorption of light in space’, Lowell Observatory bulletin , ii (1909), 1–2, p. 2.

Berendzen Hart Seeley , Man discovers the galaxies (ref. 45), 78–79.

Shapley H. , ‘Studies based on the colors and magnitudes in stellar clusters. First paper. The general problem of clusters’, Contributions from the Mount Wilson Solar Observatory , no. 115 (1915).

Smith Horace A. , ‘Bailey, Shapley, and variable stars in globular clusters’, Journal for the history of astronomy , xxxi (2000), 185–201. The discussion that follows of the development of Shapley's model of the Galaxy draws on Smith , The expanding universe (ref. 14), chap. 2 which examines this topic in more detail.

Shapley H. Bailey S. I. , 30 January 1917, Shapley Papers, Harvard University Archives.

On the globular clusters as island universes, see Smith , The expanding universe (ref. 14), 24–27.

Shapley H. Russell H. N. , 31 October 1917, Shapley Papers, Harvard University Archives.

Shapley H. Eddington A. S. , 8 January 1918, Shapley Papers, Harvard University Archives.

Shapley H. Hale G. E. , 19 January 1918, Shapley Papers, Harvard University Archives.

Bohlin K. , ‘On the galactic system with regard to its structure, origin, and relations in space’, Kungliga Svenska Vetenskaps Akadamiens Handlingar , xliii (1909), no. 10.

Hinks A. R. , ‘On the galactic distribution of gaseous nebulae and of star clusters’, Monthly notices of the Royal Astronomical Society , lxxi (1911), 693–701, p. 697.

This is a key theme of the first half of DeVorkin's D. Henry Norris Russell: Dean of American astronomers (Princeton, 2000).

Russell H. N. , ‘Astronomy notes’, Scientific American , cxviii (1918), 412.

Eddington A. S. Shapley H. , 24 October 1918, Shapley Papers, Harvard University Archives.

Schouten W. J. A. , ‘The parallax of some stellar clusters’, The observatory , xlii (1919), 112–19.

Kapteyn J. C. Van Rhihn P. J. , ‘On the distribution of the stars in space especially in the high galactic latitudes’, Astrophysical journal , lii (1920), 23–38, and Kapteyn J. C. , ‘First attempt at a theory of the arrangement and motion of the sidereal system’, Astrophysical journal , lv (1922), 302–28. See too Gingerich O. , ‘Kapteyn, Shapley and their universes’, in Van Der Kruit Van Berkel (eds), op. cit. (ref. 29), 191–212.

Shapley H. Russell H. N. , 31 March 1920, Shapley Papers, Harvard University Archives.

Smith , The expanding universe (ref. 14), 71.

Kapteyn J. C. Van Rhihn P. J. , ‘The proper motion of δ-Cephei stars and the distances of the globular clusters’, Bulletin of the Astronomical Institute of the Netherlands , i (1922), 37–42.

See particularly Smith , The expanding universe (ref. 14), chap. 2, Gingerich O. , ‘How Shapley came to Harvard: Snatching the prize from the jaws of debate’, Journal for the history of astronomy , xix (1988), 201–7, and Hoskin M. , ‘The ‘Great Debate’: What really happened’, Journal for the history of astronomy , vii (1976), 169–82. See too Smith R. W. , ‘The ‘Great Debate’ revisited’, Sky and telescope , lxv (1983), 28–30.

Smith , The expanding universe (ref. 14), 27.

Shapley H. , ‘The scale of the universe’, Bulletin of the National Research Council , ii (1921), 171–93, p. 187.

Curtis H. , ‘The scale of the universe’, Bulletin of the National Research Council , ii (1921), 194–217, p. 209.

Curtis H. Alter , 1 February 1922, Allegheny Observatory Archives.

Wilson R. E. , “The proper-motions and mean parallax of the Cepheid variables”, Astronomical journal , xxxv (1923), 35–44, p. 35.

Smith , The expanding universe (ref. 14), chap. 3.

Eddington , Stellar movements and the structure of the universe (ref. 22), 216.

Lindblad B. , ‘On the cause of star-streaming’, Astrophysical journal , lxii (1925), 191–7. On Lindblad, see Holmberg , Reaching for the stars (ref. 17), 133–61.

Lindblad B. , ‘Star-streaming and the structure of the stellar system’, Meddelanden Från Astron. Observ. Uppsala , Series C, i (1925), no. 3.

Oort J. H. , ‘Observational evidence confirming Lindblad's hypothesis of a rotation of the galactic system’, Bulletin of the Astronomical Institute of the Netherlands , iii (1927), 275–82. For Oort's thesis, see Oort J. H. , ‘The stars of high velocity’ (thesis, Groningen University), Publications of the Kapteyn Astronomical Laboratory Groningen , xl (1926), 1–75.

Jarrell R. , The cold light of dawn: A history of Canadian astronomy (Toronto, 1988), 117.

Plaskett J. S. , ‘The rotation of the Galaxy’, Monthly notices of the Royal Astronomical Society , lxxxviii (1928), 395–403. See also Eddington A. S. , The rotation of the Galaxy (Oxford, 1930).

Plaskett John S. , ‘The George Darwin Lecture 1930’, The observatory , liii (1930), 223–9, p. 228.

Shapley H. MacPherson H. , 10 December 1918, Shapley Papers, Harvard University Archives.

Shapley H. , ‘The super-galaxy hypothesis’, Harvard College Observatory circular , no. 350 (1930).

Trumpler R. J. , ‘Preliminary results on the distribution of the distances, dimensions and space distribution of open star clusters’, Lick Observatory bulletin , xiv (1930), 154–88, p. 188.

Personal communication to the author, 2 November 1977.

Eddington A. S. , The expanding universe (Cambridge, 1933), 4.

De Sitter W. , Kosmos (Cambridge, MA, 1932), 101.

Trumpler R. J. , ‘Preliminary results on the distribution of the distances, dimensions and space distribution of open star clusters’, Lick Observatory bulletin , xiv (1930), 154–88. See also O. Gingerich, ‘Robert Trumpler and the dustiness of space’, Sky and telescope , lxx (1985), 213–15, and Smith , The expanding universe (ref. 14), 158–9.

Trumpler , ‘Preliminary results on the distribution of the distances, dimensions and space distribution of open star clusters’, 166.

Ibid. .

Plaskett J. S. , The dimensions and structure of the Galaxy (Oxford, 1935).

Bok B. J. , The distribution of the stars in space (Chicago, 1937), pp. xiii and 123. This monograph was based on lectures Bok delivered at Yerkes Observatory in 1936.

Seares F. H. , ‘Some structural features of the galactic system’, Astrophysical journal , lxvii (1927), 123–78.

Trumpler , ‘Preliminary results on the distribution of the distances, dimensions and space distribution of open star clusters’ (ref. 90), 188.

Bok B. J. , The astronomer's universe (London and New York, 1958), 62.

Ibid. 63, and Gingerich O. , ‘The discovery of the spiral arms of the Milky Way’, in Van Woerden Allen Burton (eds), op. cit. (ref. 2), 59–69. Gingerich's important paper was the first full discussion of the discovery of the spiral arms and here I have followed his account. A shorter version appears in Gingerich O. , The great Copernicus chase and other adventures in astronomical history (Cambridge, MA, 1992), 263–70.

Baade W. , ‘Galaxies — present-day problems’, Publications of the University of Michigan Observatory , x (1951), 7–17.

Report on ‘Symposium on the Galaxy’, Sky and telescope , ix (1950), 243–5, p. 244.

Gingerich , ‘The discovery of the spiral arms of the Milky Way’ (ref. 98), 67.

Osterbrock D. , Walter Baade: A life in astrophysics (Princeton and Oxford, 2001), 149.

Struve O. , ‘New light on the structure of the Galaxy gained in 1952’, Leaflet of the Astronomical Society of the Pacific , no. 285 (January 1953), 275–82, p. 277.

On the development of ideas on, and efforts to detect, the 21 cm radiation, by far the best account is Sullivan's ‘Kapteyn and twentieth century Dutch astronomy’ (ref. 29). I have followed Sullivan's account here.

Oort J. , ‘Problems of galactic structure’, Astrophysical journal , cxvi (1952), 233–50.

Ewen H. Purcell E. , ‘Radiation from galactic hydrogen at 1,420 MHz’, Nature , clxviii (1951), 356.

See, for example, Oort J. Kerr F. J. Westerhout G. , ‘The galactic system as a spiral nebula’, Monthly notices of the Royal Astronomical Society , cxviii (1958), 379–89.

Osterbrock , Walter Baade (ref. 102), 102.

Baade W. , “The resolution of Messier 32, NGC 205, and the central region of the Andromeda Nebula”, Astrophysical journal , c (1944), 137–46.

Minutes for the session were taken by Fred Hoyle, and appeared in the Transactions of the International Union. Eighth General Assembly held at ROME, 4 September to 13 September 1952 , viii (1954), 397–8, p. 397.

Baade did not make this point in Rome, but Morgan and his collaborators had reckoned the size of, and distances to, the spiral arms with the aid of population I objects so these sizes and distances needed to be amended.

Shapley did, however, as Osterbrock has described, make unwarranted claims that he should get the credit for the revisions to the distance scale, claims that led a furious Baade to describe Shapley as a ‘wind bag’ and a ‘carnival barker’ in private correspondence. On this controversy, see Osterbrock , Walter Baade (ref. 102), 171–4. On Baade's revision of the distance scale, the best account is Osterbrock , Walter Baade , 162–76. Baade presented his account of the different period-luminosity curves for the two populations of Cepheids in ‘The period-luminosity relation of the Cepheids’, Publications of the Astronomical Society of the Pacific , lxviii (1956), 5–16.

Struve O. , ‘The distance scale of the universe — I’, Sky and telescope , xii (1953), 203–5, p. 203. See also the second part of Struve's report in ‘The distance scale of the universe — II’, Sky and telescope , xii (1953), 238–40.