The Planet Mars:
A History of Observation and Discovery

William Sheehan



Notes

Chapter 1. Motions of Mars

1. It was Georg Joachim Rheticus, the pupil of Copernicus, according to Kepler, Astronomia Nova, in Johannes Kepler, Gesammelte Werke, 22 vols., ed. W. von Dyck and Max Caspar (Munich: C. H. Beck, 1937), vol. 3, p. 8.

2. Copernicus, "Commentariolus," in Three Copernican Treatises, 2d ed., trans. Edward Rosen (New York: Dover, 1959), pp. 77--78.

3. For biographical details about Tycho Brahe, see Victor E. Thoren, The Lord of Uraniborg: A Biography of Tycho Brahe (Cambridge: Cambridge University Press, 1990).

4. Kepler, Astronomia Nova, cap. 7, in Gesammelte Werke, vol. 3, p. 108. On Kepler, the standard source is Max Caspar, Kepler, trans. C. Doris Hellman (1959; reprint, New York: Dover, 1993). Technical accounts of Kepler's calculations are in J. L. E. Dreyer, A History of Astronomy from Thales to Kepler (1906; reprint, New York: Dover, 1953); Antonie Pannekoek, A History of Astronomy (1961; reprint, New York: Dover, 1989); Alexandre Koyré, The Astronomical Revolution, trans. R. E. W. Maddison (1973; reprint, New York: Dover, 1992); and, especially, Curtis Wilson, "How Did Kepler Discover His First Two Laws?" Scientific American 226 (1972): 93--106.

5. Kepler, Astronomia Nova, cap. 7, in Gesammelte Werke, vol. 3, p. 108.

6. The full title is Astronomia Nova a t t sue Physica Coelestis, tradita Commentariis de Motibus Stellae Martis. Ex Observationibus G. V. Tychonis Brahe. An English translation is available as New Astronomy, trans. William H. Donohue (Cambridge: Cambridge University Press, 1993).

7. Kepler, Astronomia Nova, Epistola Dedicatoria, in Gesammelte Werke, vol. 3, p. 8; Koyré, The Astronomical Revolution, pp. 277--278.

Chapter 2. Pioneers

1. A very good recent English translation has been produced by Albert van Helden, Sidereus Nuncius, or the Sidereal Messenger (Chicago: University of Chicago Press, 1989).

2. Galileo Galilei, Le Opere di Galileo Galilei, Edizione Nationale, 20 vols., ed. Antonio Favaro (Florence: G. Barbera, 1890--1909; reprinted 1929--39, 1964--66), vol. 10, p. 503.

3. Kepler, Conversation with Galileo's Sidereal Messenger, trans. Edward Rosen (New York: Johnson Reprint Co., 1965), pp. 14, 77.

4. Kepler, Dioptrice (Augsburg, 1611); trans. in E. S. Carlos, A part of the preface of Kepler's Dioptrics, forming a continuation of Galileo's Sidereal Messenger (London, 1880; reprint, Dawsons of Pall Mall, 1960), p. 88.

5. Galileo, Opere, vol. 10, p. 474.

6. F. Fontana, Novae Coelestium Terrestriumque rerum observationes (Naples, 1646).

7. C. Flammarion, La planète Mars, et ses conditions d'habitabilité, 2 vols. (Paris: Gauthier-Villars et Fils, 1892), vol. 1, p. vii.

8. See Albert van Helden, "`Angulo Cingitur': The Solution of the Problem of Saturn," Journal for the History of Astronomy 5 (1974): 155--174.

9. Huygens's sketches and notes are reproduced in F. Terby, "Aréographie, ou étude comparative des observations faites sur l'aspect physique de la planète Mars depuis Fontana (1636) jusqu'à nos jours (1873)," in Mémoirs des savants étrangers de l'Académie Royale des Sciences de Belgique 39 (1875), at p. 8.

10. Flammarion, La planète Mars, vol. 1, p. 16.

11. G. D. Cassini to M. Petit, June 18, 1667, "Extrait d'une lettre de M. Cassini . . . a M. Petit," Le Journal des Sçavans pour l'anné mdclxii (reprint, Paris, 1729), pp. 122--125.

12. G. D. Cassini, Martis circa proprium axem revolubilis observationes Bononiae habitae (Bologna, 1666), and Dissertatio apologetica de maculis Jovis et Martis (Bologna, 1666).

13. Robert Hooke, Philosophical Transactions of the Royal Society of London (London, 1665--1666), vol. 1, p. 239.

14. C. Huygens, Oeuvres Complètes, 21 vols. (The Hague: Société Hollandaise des Sciences, 1888--1950), vol. 21, p. 224.

15. Quoted in Willy Ley, Watchers of the Skies (New York: Viking Press, 1963), p. 169.

16. For a complete discussion, see Albert van Helden, Measuring the Universe: Cosmic Dimensions from Aristarchus to Halley (Chicago: University of Chicago Press, 1989).

17. Bernard le Bovier de Fontenelle, Conversations on the Plurality of Worlds, trans. H. A. Hargreaves (Berkeley: University of California Press, 1990), p. 52.

18. Steven J. Dick, Plurality of Worlds: The Origins of the Extraterrestrial Life Debate from Democritus to Kant (Cambridge: Cambridge University Press, 1982), p. 129.

19. Huygens, Oeuvres, vol. 21, p. 701; the English edition is The Celestial Worlds Discover'd: or, Conjectures concerning the Inhabitants, Plants and Productions of the Worlds in the Planets (London, 1698), p. 21.

20. Quoted in Joseph Ashbrook, The Astronomical Scrapbook: Skywatchers, Pioneers and Seekers in Astronomy (Cambridge, Mass.: Sky Publishing, 1984), p. 127.

Chapter 3. "A Situation Similar to Ours"

1. The 1704 observations are described in G. Maraldi, "Observations des taches de Mars pour vérifier sa révolution autour de son axe," Histoire et Mémoires de l'Académie des Sciences (Paris, 1706), p. 74; those of 1719 are in "Nouvelle observations de Mars," Histoire et Mémoires (Paris, 1720), p. 144. Incidentally, at the 1719 opposition, the planet's brightness, or perhaps its color---it seems to have been even more than usually red that year---caused a panic. Many believed it to be a nova or red comet portending calamity.

2. W. Herschel, "Astronomical Observations on the Rotation of the Planets," Philosophical Transactions of the Royal Society 81, pt. 1 (1781): 115.

3. Mrs. J. Herschel, Memoir and Correspondence of Caroline Herschel (New York: D. Appleton, 1876), p. 53.

4. W. Herschel, "On the remarkable Appearances at the Polar Regions of the Planet Mars, the Inclination of its Axis, the Position of its Poles, and its spheroidical Figure; with a few Hints relating to its real Diameter and Atmosphere," Philosophical Transactions of the Royal Society of London 74 (1784): 233--273.

5. Ibid.

6. Ibid.

7. Ibid.

8. Schroeter's bibliography includes Beobachtungen vershiedener schwarzdunkler Flecken des Jupiters (Lilienthal, 1786); Beobachtungen über die Sonnefackeln und Sonnenflecken (Erfurt, 1789); Selenotopographische Fragmente über den Mond (Helmstedt, 1791); Aphroditographische Fragmente zur genauern Kenntniss des Planeten Venus (Helmstedt, 1796); Selenotopographische Fragmente über den Mond, 2d Band (Göttingen, 1802); Kronographische Fragmente zur genauern Kenntniss des Planeten Saturn (Göttingen, 1808), a second part was destroyed in the fire of 1813, see below; Beobachtungen des grossen cometen von 1807 in physischer Hinsicht (Göttingen, 1811); and Hermographische Fragmente zur genauern Kenntniss des Planeten Mercur (Göttingen, 1816).

9. J. H. Schroeter, Areographische Beiträge zur genauern Kenntnis und Beurtheilung des Planeten Mars, ed. H. G. van de Sande Bakhuyzen (Leiden, 1881), p. 1.

10. Ibid., p. 2.

11. Though Schroeter confirmed the basic rotation period of the planet, he found irregularities in his measures of its markings which he attributed to real cloud movements. If his measures yielded a period that was too short, he concluded that the markings had an independent motion due to winds blowing in the same direction as the rotation; if too long, the motion was produced by winds blowing in the opposite direction. From such evidence he compiled a table of Martian wind velocities, which, we now know, was sheer fantasy.

12. Ibid., p. 430.

13. Ibid., p. 440.

14. A description of the destruction of Lilienthal is in Richard Baum, "The Lilienthal Tragedy," Journal of the British Astronomical Association 101 (1991): 369--371. Baum gives as his source a letter by W. F. Denning to The Observatory dated July 4, 1904, while Denning in turn cites J. Hemingway, The Northern Campaigns and History of the War, from the Invasion of Russia in 1812 (Manchester, 1815).

15. Tischbein has sometimes been accused of being a clumsy engraver and responsible at least in part for the charge often leveled against Schroeter that he was a clumsy draftsman. A comparison of Schroeter's pencil drawings of Mars with Tischbein's copperplates, however, exonerates the engraver.

16. F. Terby, "Aréographie, ou étude comparative des observations faites sur l'aspect physiquede la planète Mars depuis Fontana (1636) jusqu'à nos jours (1873)," Mémoires des savants étrangers de l'Académie Royale des Sciences de Belgique 39 (1875).

17. Bakhuyzen, Foreword to Schroeter, Areographische Beiträge.

18. Ashbrook, The Astronomical Scrapbook: Skywatchers, Pioneers and Seekers in Astronomy (Cambridge, Mass.: Sky Publishing, 1984), p. 290.

Chapter 4. Areographers

1. Henry C. King, The History of the Telescope (1955; reprint, New York: Dover, 1979), p. 68.

2. Ibid., p. 160.

3. H. de Flaugergues, "Les taches de la planète Mars," Journal de Physique (Paris) 69 (1809): 126; Baron Franz Xaver von Zach, Correspondenz, vol. 1 (Gotha, 1818), p. 180.

4. See, for example, C. F. Capen and L. J. Martin, "The Developing Stages of the Martian Yellow Storm of 1971," Lowell Observatory Bulletin, no. 157, vol. 3, pp. 211--216.

5. G. K. F. Kunowsky, "Einige physische Beobachtungen des Mondes, des Saturns, und Mars," Astronomisches Jahrbuch für 1825 (Berlin, 1822).

6. C. Flammarion, La planète Mars, et ses conditions d'habitabilité, 2 vols. (Paris: Gauthier-Villars et Fils, 1892), vol. 1, p. 101.

7. The most complete information on Mädler is in Heino Eelsau and Dieter B. Hermann, Johann Heinrich Mädler, 1794--1874 (Berlin: Akademie Verlag, 1985).

8. Beer and Mädler's investigations on Mars were published in Astronomische Nachrichten in 1831, 1834, 1835, 1838, and 1839. These investigations were later collected into a book, which appeared in both French and German editions: Fragmente sur les corps celestes du système solaire (Paris, 1840), and Beiträge zur physischen Kenntniss der himmlischen Körper im Sonnensysteme (Weimar, 1841). Mädler's 1841 investigations were published in Astronomische Nachrichten in 1842.

9. Beer and Mädler, "Physische Beobachtungen des Mars bei seiner Opposition im September 1830," Astronomische Nachrichten 191 (1831): 447--456, at p. 448.

10. Ibid., p. 450.

11. F. Arago, Astronomie populaire (Paris, 1854--57), vol. 4, p. 136.

12. A. Secchi, Osservazioni di Marte, fatte durante l'opposizione del 1858. Memorie dell'Osservatorio del Collegio Romano (Rome, 1859).

13. A. Secchi, Osservazioni del pianeta Marte. Memorie dell'Osservatorio del Collegio Romano, n.s., 2 (Rome, 1863).

14. F. Kaiser, "Untersuchungen über den planeten Mars bei dessen oppositionen in der Jahren 1862 und 1864," in Annalen der Sternwarte in Leiden, Dritter Band (The Hague, 1872), pp. 1--87.

15. J. Norman Lockyer, "Measures of the Planet Mars in 1862," Monthly Notices of the Royal Astronomical Society 32

(1862): 179--190.

16. E. M. Antoniadi, "The Hourglass Sea on Mars," Knowledge, July 1, 1897, pp. 169--172, at p. 170.

17. G. V. Schiaparelli, "Osservazioni astronomiche e fisiche sull'asse di rotazione e sulla topographia del pianeta Marte," Atti della R. Accademia dei Lincei, Memoria 1, ser. 3, vol. 2 (1877--78), in Le Opere di G. V. Schiaparelli, 10 vols. (1930; reprint, New York: Johnson Reprint Co., 1969), vol. 1, p. 63n.

18. E. Liais, L'espace céleste et la natur tropicale (Paris, 1865). He was not the first to suggest that there was vegetation on Mars. That suggestion had already been made by the French astronomer J. H. Lambert, who had died in 1777. Lambert had surmised that the vegetation on Mars was reddish, a view later revived by Camille Flammarion.

19. R. A. Proctor, Half-hours with the Telescope (London, 1896), p. 203.

20. Flammarion, La planète Mars, vol. 1, p. 204.

21. W. R. Dawes, "On the Planet Mars," Monthly Notices of the Royal Astronomical Society 25 (1865): 225--268.

22. The map was first published in Proctor, Half-hours with the Telescope, plate 6. It appeared, in somewhat different forms, in Proctor's other works: Other Worlds than Ours (London, 1870), p. 92; The Orbs around Us (London, 1872), frontispiece; Essays on Astronomy (London, 1872), p. 61; etc.

23. G. V. Schiaparelli, "Osservazioni astronomiche e fisiche sull'asse di rotazione e sulla topographia del pianeta Marte," Atti della R. Accademia dei Lincei, Memoria 1, ser. 3, vol. 2 (1877--78), in Le Opere di G. V. Schiaparelli, 10 vols. (1930; reprint, New York: Johnson Reprint Co., 1969), vol. 1, p. 129.

24. P. A. Secchi, Memorie dell'Osservatorio del Collegio Romano (Rome, 1858), vol. 1, no. 3, p. 22.

25. Quoted in W. F. Denning, Telescopic Work for Starlight Evenings (London, 1891), p. 125.

Chapter 5. 1877

1. A. Hall, "My Connection with the Harvard Observatory and the Bonds---1857--1862," in Edward Singleton Holden, Memoirs of William Cranch Bond and of His Son George Phillips Bond (San Francisco, 1897), pp. 77--78.

2. A. Hall to S. C. Chandler, Jr., March 7, 1904, quoted in Owen Gingerich, "The Satellites of Mars: Prediction and Discovery," Journal for the History of Astronomy 1 (1970): 109--115, at p. 113.

3. A. Hall, "The Period of Saturn's Rotation," Monthly Notices of the Royal Astronomical Society 38 (1877--78): 209.

4. A. Hall to E. C. Pickering, February 14, 1888, Harvard College Observatory Archives.

5. A. Hall to E. C. Pickering, February 7, 1888, Harvard College Observatory Archives.

6. A. Hall, "The Discovery of the Satellites of Mars," Monthly Notices of the Royal Astronomical Society 38 (1877--78): 205--208, as supplemented by Gingerich, "The Satellites of Mars," and Steven J. Dick, "Discovering the Moons of Mars," Sky & Telescope 76 (1988): 242--243.

7. A. Hall to Arthur Searle, October 9, 1877, Harvard College Observatory Archives.

8. A. Hall to E. C. Pickering, October 30, 1877, Harvard College Observatory Archives.

9. Richard A. Proctor, "Note from Mr. Proctor," Sidereal Messenger 6 (1887): 259--262, at p. 260.

10. A. Hall to S. C. Chandler, Jr., March 7, 1904, quoted in Gingerich, "The Satellites of Mars."

11. Ibid.

12. N. E. Green, "Observations of Mars, at Madeira in Aug. and Sept. 1877," Memoirs of the Royal Astronomical Society 40 (1880): 123--140.

13. H. Pratt, "Notes on Mars, 1877," Monthly Notices of the Royal Astronomical Society 38 (1877--78): 61--63, at p. 62.

14. Unfortunately, there is as yet no really satisfactory biography of Schiaparelli. Sources I consulted include Piero Bianucci, "Giovanni Virginio Schiaparelli," L'Astronomia 6 (1980): 45--48; E. Fergola et al., All'Astronomo G. V. Schiaparelli-Omaggio---30 Giugno 1860--30 Giugno 1900 (Milan, 1900), which gives a chronology of his life and lists his most important publications; and G. Cossavella, L'Astronomo Giovanni Schiaparelli (Turin, 1914), as well as various necrological sources. The standard edition of Schiaparelli's works is Le Opere di G. V. Schiaparelli (1930; reprint, New York: Johnson Reprint Co., 1969).

15. Quoted in Piero Bianucci, "Giovanni Virginio Schiaparelli," L'Astronomia 6 (1980): 45--48, at p. 45.

16. Hector MacPherson, Makers of Astronomy (Oxford, 1893), p. 189.

17. G. V. Schiaparelli, "Intorno al corso ed all'origine probabile delle Stella Meteoriche; Lettere al P. A. Secchi," Bulletino Meteorologico dell'Osservatorio del Collegio Romano, vols. 5 and 6 (1866--67), in Opere, vol. 3, pp. 261--316.

18. R. G. Aitken, "The Orbit of ß Delphini," Popular Astronomy 11 (1903): 30--34.

19. In a dozen years of observation, Schiaparelli failed to see any spots as marked as those of 1877--78. He announced his result in "Considerazioni sul moto rotatorio del pianeta Venere" (1890), in Opere, vol. 5, pp. 361--428. In 1895 he published similar observations which he felt "put the final seal of certainty on the rotation of 224.7 days" (Schiaparelli to F. Terby, July 31, 1895, in Bulletin de l'Académie de Belgique, August 1895).

20. The solid body of Venus rotates in a retrograde direction, with a period of 243 days. The surface of the planet is, however, hidden by clouds, which sweep around the planet in only 4 days.

21. Schiaparelli, "Sulla rotazione di Mercurio," Astronomische Nachrichten, no. 2944 (1889): 247.

22. Schiaparelli, "Sulla rotazione e sulla costituzione del pianeta Mercurio" (1889), in Opere, vol. 5, p. 343.

23. As noted in A. Dollfus and H. Camichel, "La rotation et la cartographie de la planète Mercure," Icarus 8 (1968): 216--226.

24. This is not the case in the Southern Hemisphere; if Schiaparelli and Antoniadi had made their observations there, the true rotation period of Mercury might have been established long ago. See B. A. Smith and E. J. Reese, "Mercury's Rotation Period: Photographic Confirmation," Science 162 (1968): 1275--1277.

25. Clark R. Chapman and Dale P. Cruikshank, "Mercury's Rotation and Visual Observations," Sky & Telescope 34 (1967): 24--26, at p. 25.

26. E. M. Antoniadi, The Planet Mars, trans. Patrick Moore (Shaldon Devon, U.K.: Keith Reid, 1975), p. 260.

27. Schiaparelli, "Osservazioni astronomiche e fisiche sull'asse di rotazione e sulla topografia del pianeta Marte," Atti della R. Accademia dei Lincei, Memoria 1, ser. 3, vol. 2, in Le Opere di G. V. Schiaparelli, 10 vols. (1930; reprint, New York: Johnson Reprint Co., 1969), vol. 1, pp. 11--175, at pp. 11--12.

28. Flammarion, La planète Mars, vol. 1, p. 294.

29. Schiaparelli, "Osservazioni astronomiche e fisiche," p. 61. A valuable monograph on the nomenclature of Mars is Jürgen Blunck, Mars and Its Satellites: A Detailed Commentary on the Nomenclature (Hicksville, N.Y.: Exposition Press, 1977).

30. Schiaparelli, "Osservazioni astronomiche e fisiche," p. 61.

31. Ibid.

32. P. Lowell, Mars (Boston: Houghton Mifflin, 1895), p. 157.

33. Flammarion, La planète Mars, vol. 1, p. 301.

34. Schiaparelli, "Il pianeta Marte ed i moderni telescopi" (1878), in Opere, vol. 1, pp. 179--200, at p. 188.

35. Concerning the terms channel and canal, I quote from the Oxford English Dictionary (1971): "The words canel, CANNEL, and chanel, CHANNEL, from the same Latin source, but immediately from old French, were in much earlier use in Eng[lish]; when canal was introduced it was to some extent used as a synonym of these, but the forms were at length differentiated." The term canal is, however, taken to refer specifically to "an artificial watercourse constructed to unite rivers, lakes, or seas, and serve the purposes of inland navigation. (The chief modern sense, which tends to influence all the others.)" Schiaparelli himself never approved of canal; see Schiaparelli, Corrispondenza su Marte, 2 vols. (Pisa: Domus Galilaeana, 1976), vol. 2, p. 259.

36. Giovanni Cossavella, L'Astronomo Giovanni Schiaparelli, p. 10.

37. Schiaparelli, "Osservazioni astronomiche e fisiche," p. 164.

38. Color-blind people perceive any modification of the intensity of light as a change of color, and they are more sensitive to contrast effects than those with normal color vision. Though Schiaparelli generally gave hard and sharp outlines to the dark areas and represented slight differences of shade as hard, sharp lines, he did have perceptions of more delicate structure of these areas. Thus he wrote that part of Libya "had the appearance of a shaggy rug, or if you wish, gave the impression of a crowd of minute pores" (in "Osservazioni astronomiche e fisiche sull'asse di rotatione e sulla topografia del pianeta Marte," Atti della R. Accademia dei Lincei, Memoria 3, in Opere, vol. 1, p. 472). On p. 479 of the same work he quoted his observation of February 4, 1882: "Tyrrhenum is very beautiful and dark. Ausonia well terminated along it, seeming like froth floating above it, or of something porous." He noted that "an analogous resemblance to foam or a surface full of pores has been offered at times by Iapygia and Libya. A fleecy aspect was seen in Iapygia in 1879. And also in Libya. Perhaps with increasing power of the telescope one could judge if there is something real in such unusual appearances."

39. Lowell, Mars, p. 157.

40. Schiaparelli, "Osservazioni astronomiche e fisiche," p. 151.

41. Ibid.

Chapter 6. Confirmations and Controversies

1. Schiaparelli, "Osservazioni astronomiche e fisiche sull'asse di rotazione e sulla topografia del pianeta Marte," Atti della R. Accademia dei Lincei, Memoria 2 (Osservazioni dell'opposizione 1879--80), in Le Opere di G. V. Schiaparelli, 10 vols. (1930; reprint, New York: Johnson Reprint Co., 1969), vol. 1, p. 244.

2. Ibid., pp. 334--335.

3. Ibid., p. 386.

4. G. V. Schiaparelli to N. E. Green, October 27, 1879, cited by Green in "Mars and the Schiaparelli Canals," Observatory 3 (1879): 252.

5. Ibid.

6. As reported in The Astronomical Register 17 (1879): 47--48.

7. T. W. Webb, "Planets of the Season: Mars," Nature 34 (1886): 213.

8. "Report of the Meeting of the Association held Dec. 31, 1890," Journal of the British Astronomical Association 1 (1890): 112.

9. Schiaparelli, "Osservazioni astronomiche e fisiche," p. 302.

10. Schiaparelli, "Osservazioni sulla topografia del pianeta Marte . . . durante l'opposizione 1881--1882---Communicazione Preliminare," in Opere, vol. 1, pp. 381--388, at p. 385.

11. Ibid., pp. 385--386.

12. Flammarion, La planète Mars, et ses conditions d'habitabilité, 2 vols. (Paris: Gauthier-Villars et Fils, 1892), vol. 1, p. 362.

13. Quoted in T. J. J. See, "The Study of Planetary Detail," Popular Astronomy 4 (1897): 553.

14. Flammarion, La planète Mars, vol. 1, p. 446.

15. Ibid., p. 389.

16. R. A. Proctor, "Maps and Views of Mars," Scientific American, supplement, 26 (1888): 10659--10660.

17. Flammarion, La planète Mars, vol. 1, p. 412.

18. H. Perrotin, "Observations des canaux de Mars," Bulletin Société Astronomique de France 3 (1886): 324--329.

19. Terby, "Physical Observations of Mars," Astronomy and Astro-Physics 11 (1892): 479--480.

20. E. H. Gombrich, Art and Illusion: A Study in the Psychology of Pictorial Representation, 2d ed. (Princeton, N.J.: Bollingen Press, 1961), p. 204.

21. Perrotin, "Les canaux de Mars. Nouveaux changements observes sur cette planète," Astronomie 7 (1888): 213--215.

22. Quoted in Flammarion, La planète Mars, vol. 1, p. 510.

23. J. E. Keeler, "First Observations of Saturn with the 36-Inch Refractor of the Lick Observatory," Sidereal Messenger 7 (1888): 79--83.

24. New York Common Advertiser, November 1888.

25. Flammarion, La planète Mars, vol. 1, pp. 426--430.

26. Schiaparelli to O. Struve, July 6, 1878, in Corrispondenza su Marte, 2 vols. (Pisa: Domus Galilaeana, 1976), vol. 1, pp. 14--18.

27. Flammarion, La planète Mars, vol. 1, p. 425.

28. Ibid.

29. Schiaparelli to Terby, June 12, 1890, in Corrispondenza su Marte, vol. 2, pp. 29--31.

30. E. S. Holden, "Note on the Opposition of Mars, 1890," Publications of the Astronomical Society of the Pacific 2 (1890): 299--300.

31. E. S. Holden, J. M. Schaeberle, and J. E. Keeler, "White Spots on the Terminator of Mars," Publications of the Astronomical Society of the Pacific 2 (1890): 248--249.

32. San Francisco Chronicle, June 2, 1895.

33. As quoted in Flammarion, "Idée d'un communication entre les mondes," L'Astronomie 10 (1891): 282.

34. R. W. Sinnott, "Mars Mania of Oppositions Past," Sky & Telescope 76 (1988): 244--246.

35. As noted in G. E. Hale, "The Aim of the Yerkes Observatory," Astrophysical Journal 6 (1897): 310--321, at pp. 320--321.

36. Flammarion, "How I Became an Astronomer," North American Review 150 (1890): 100--195, at p. 102. For more details about Flammarion, consult his autobiography, Mémoires: biographiques et philosophiques d'un astronome (Paris: E. Flammarion, 1911), which covers the first thirty years of his life; and Philippe de la Cotardière and Patrick Fuentes, Camille Flammarion (Paris: Flammarion, 1994).

37. Robert H. Sherard, "Camille Flammarion at Home," San Francisco Call, May 28, 1893.

38. Flammarion, La planète Mars, vol. 1, p. 515.

39. Ibid.

40. Ibid.

41. Ibid., p. 579.

42. Ibid., pp. 580, 586.

43. Ibid., p. 586.

44. C. A. Young, "Observation of the Red Spot of Jupiter," Observatory 8 (1885): 172--174.

45. Quoted in W. F. Denning, Telescopic Work for Starlight Evenings (London, 1891), p. 125.

46. G. V. Schiaparelli, "Il pianeta Marte ed i moderni telescopi," Nuova Antologia, ser. 2, vol. 9 (Rome, 1878), in Opere, vol. 1, pp. 179--200, at p. 197. Compare Isaac Newton in the Opticks (1707): "If the Theory of making Telescopes could at length be fully brought into Practice, yet there would be certain Bounds beyond which Telescopes could not perform. For the Air through which we look upon the Stars, is in a perpetual Tremor. . . . The only Remedy is a most serene and quiet Air such as may perhaps be found on the tops of the highest Mountains above the grosser Clouds."

47. Agnes M. Clerke, A Popular History of Astronomy during the Nineteenth Century, 3d ed. (London: Adam and Charles Black, 1893), p. 519.

48. E. S. Holden, "The Lowell Observatory in Arizona," Publications of the Astronomical Society of the Pacific 6 (1894): 160--169, at p. 165.

49. W. H. Pickering, "Mars," Astronomy and Astro-Physics 11 (1892): 668--672.

50. Ibid., p. 669.

51. Ibid., p. 670.

52. Clerke, Popular History of Astronomy, p. 344.

53. Ibid.

Chapter 7. Lowell

1. William Graves Hoyt, Lowell and Mars (Tucson: University of Arizona Press, 1976), p. 12. Lowell's continuing fascination is attested by the fact that he has been the subject of several biographies. In addition to Hoyt's there is a biography by Lowell's brother, Abbott Lawrence Lowell, Biography of Percival Lowell (New York: Macmillan, 1935). Ferris Greenslet's The Lowells and Their Seven Worlds (Boston: Houghton Mifflin, 1946), contains much original information about Lowell and his family. Another important source is William Lowell Putnam, The Explorers of Mars Hill: A Centennial History of Lowell Observatory (West Kennebunk, Maine: Phoenix, 1994). Hoyt's Planets X and Pluto (Tucson: University of Arizona Press, 1980) is a thorough account of Lowell's mathematical and observational quest for a trans-Neptunian planet, which occupied much of his time and energy after the turn of the century. What is likely to be the authoritative biography is now being written by David Strauss, who has already completed an excellent account of the early history of the founding of the Lowell Observatory: "Percival Lowell, W. H. Pickering, and the Founding of the Lowell Observatory," Annals of Science 51 (1994): 37--58, which I follow closely here.

2. Greenslet, The Lowells and Their Seven Worlds, p. 366.

3. Nathan Appleton, The Introduction of the Power Loom and the Origin of Lowell (Boston, 1858), p. 9.

4. Amy Lowell, "Sevenels, Brookline, Mass.," Touchstone 7 (1920): 210--218.

5. Quoted in Wrexie Louise Leonard, Percival Lowell: An Afterglow (Boston: Badger Press, 1921), p. 25.

6. P. Lowell, "Reply to Newcomb," Astrophysical Journal 26 (1907): 131.

7. David Strauss, "`Fireflies Flashing in Unison': Percival Lowell, Edward Morse and the Birth of Planetology," Journal for the History of Astronomy 24 (1993): 157--169, at p. 160.

8. A. L. Lowell, Biography of Percival Lowell, p. 12.

9. Greenslet, The Lowells and Their Seven Worlds, p. 349.

10. David Strauss, "The `Far East' in the American Mind, 1883--1894: Percival Lowell's Decisive Impact," Journal of American--East Asian Relations 2 (1993): 217--241, at p. 225.

11. Greenslet, The Lowells and Their Seven Worlds, p. 349.

12. Ibid.

13. The Soul of the Far East and Noto were prepublished in the Atlantic Monthly.

14. P. Lowell, "Noto," Atlantic Monthly 67 (1891): 500.

15. Greenslet, The Lowells and Their Seven Worlds, p. 355.

16. Flammarion later wrote that Lowell had told him that "his passion for astronomy, in particular for the discoveries he made in the world of Mars, had been inspired by the publication of this book" (C. Flammarion, "Percival Lowell," Bulletin Société Astronomique de France 30 [1916]: 423).

17. P. Lowell to E. C. Pickering, February 14, 1894, E. C. Pickering Papers, Harvard University Archives.

18. S. C. Chandler to E. S. Holden, September 4, 1894, Mary Lea Shane Archives of Lick Observatory.

19. The scale was as follows: 0, diffraction disk and rings confused and enlarged; 2, disk and rings confused but not enlarged; 4, disk defined; no evidence of ring; 6, rings broken but traceable; 8, rings complete but moving; 10, rings motionless.

20. P. Lowell to A. E. Douglass, April 16, 1894, Lowell Observatory Archives.

21. The quotation is from Strauss, "Percival Lowell, W. H. Pickering and the Founding of the Lowell Observatory," p. 37.

22. W. W. Campbell, review of Mars, by Percival Lowell, Publications of the Astronomical Society of the Pacific 51 (1896): 207.

23. Quoted in A. L. Lowell, Biography of Percival Lowell, p. 72.

24. P. Lowell, observing notebooks, Lowell Observatory Archives.

25. P. Lowell, Mars and Its Canals (New York: Macmillan, 1906), p. 149.

26. P. Lowell, observing notebooks, Lowell Observatory Archives.

27. W. H. Pickering, "The Seas of Mars," Astronomy and Astro-Physics 13 (1894): 553--556.

28. Lowell, "The Polar Snows," Popular Astronomy 2 (1894): 52--56.

29. Lowell, "Spring Phenomena," Popular Astronomy 2 (1894): 97--100.

30. Ibid., p. 100.

31. Lowell, "The Canals---I," Popular Astronomy 2 (1894): 255--261, at p. 261.

32. Lowell, "Oases," Popular Astronomy 2 (1895): 343--348, at p. 348.

33. Ray Bradbury, Arthur C. Clarke, Bruce Murray, Carl Sagan, and Walter Sullivan, Mars and the Mind of Man (New York: Harper and Row, 1973), p. 11.

34. Lowell, "Mars," Popular Astronomy 2 (1894): 1--8.

35. Lowell, "The Canals---I," p. 258.

36. J. E. Keeler to G. E. Hale, December 27, 1894, Yerkes Observatory Archives.

37. Greenslet, The Lowells and Their Seven Worlds, p. 366.

38. Quoted in A. L. Lowell, Biography of Percival Lowell, p. 93. Flammarion published his own account of their conversation in 1896 in "Recent Observations of Mars," Scientific American 74 (February 29, 1896): 133--134.

39. Flammarion, "La planète Mars," L'Astronomie 13 (1894): 321--329, at p. 328.

40. Flammarion, La planète Mars, et ses conditions d'habitabilité, 2 vols. (Paris: Gauthier-Villars et Fils, 1909), vol. 2, p. 135.

41. Flammarion, "Mars and Its Inhabitants," North American Review 162 (May 1896): 546--557.

42. Schiaparelli to F. Terby, November 30, 1896, in Corrispondenza su Marte, vol. 2, p. 137.

43. Schiaparelli to F. Terby, January 27, 1895, in Corrispondenza su Marte, vol. 2, pp. 166--167.

44. Schiaparelli to O. Struve, May 1, 1898, in Corrispondenza su Marte, vol. 2, pp. 278--280.

45. Schiaparelli, "Il pianeta Marte," Opere, vol. 2, pp. 47--74; the third and fourth parts of this four-part essay appeared as "The Planet Mars," trans. W. H. Pickering, Astronomy and Astro-Physics 13 (1894): 635--640, 714--723.

46. Schiaparelli, "La vita sul pianeta Marte," Natura ed Arte 4 (June 1, 1895), in Opere, vol. 2, pp. 83--95, at p. 88.

47. Ibid., p. 91.

48. Ibid.

49. His comment to Flammarion was published in a note to Flammarion's translation of "La vita sul pianeta Marte," which was published as "La vie sur la planète Mars" in Bulletin Société Astronomique de France 12 (1898): 429--429. To George Comstock of the Washburn Observatory of the University of Wisconsin, he explained in 1897: "I pray you not to take [this paper] too seriously; it is a lupus ingenii whose purpose is to show that it is possible to explain some of the mysterious phenomena of Mars without assuming anything very extraordinary or different from what one finds on Earth" (Corrispondenza su Marte, vol. 2, p. 235).

50. Quoted in Hector McPherson, "The Problem of Mars," Popular Astronomy 29 (1921): 129--137, at p. 133.

51. Schiaparelli, Corrispondenza su Marte, vol. 2, p. 192.

52. Schiaparelli, "Observations of the Planet Mars," Opere, vol. 2, p. 249.

53. E. M. Antoniadi, "Mars Section, Fifth Interim Report, 1909," Journal of the British Astronomical Association 20 (1909): 138.

Chapter 8. How the Eye Interprets

1. W. W. Campbell, "The Spectrum of Mars," Publications of the Astronomical Society of the Pacific 6 (1894): 228--236.

2. E. E. Barnard, Nashville Artisan, August 10, 1883. The standard biography of E. E. Barnard is William Sheehan, The Immortal Fire Within: The Life and Work of Edward Emerson Barnard (Cambridge: Cambridge University Press, 1995).

3. Barnard, "Mars: His Moons and His Heavens" (unpublished manuscript in the Vanderbilt University Archives).

4. "E. E. Barnard's Visit with G. V. Schiaparelli in Milan" (manuscript in the Vanderbilt University Archives); it was published by George Van Biesbroeck in Popular Astronomy 42 (1934): 553--558.

5. Barnard, observing notebooks, Lick Observatory.

6. Ibid.

7. E. E. Barnard to S. Newcomb, September 11, 1894, Simon Newcomb Papers, Library of Congress.

8. Ibid.

9. Ibid.

10. Noted in "Proceedings of the Meeting of the Royal Astronomical Society, April 14, 1882," Observatory 5 (1882): 135--137.

11. E. Walter Maunder, "The Tenuity of the Sun's Surroundings," Knowledge, March 1, 1894, pp. 49--50, at p. 49.

12. Ibid.

13. Maunder, "The Canals of Mars," Knowledge, November 1, 1894, pp. 249--252, at p. 251.

14. Ibid., p. 252.

15. W. G. Hoyt, Lowell and Mars (Tucson: University of Arizona Press, 1976), p. 201.

16. A. L. Lowell, Biography of Percival Lowell (New York: Macmillan, 1935), p. 66, quoting from an unpublished paper written by Percival Lowell in 1897 which was intended to be the introduction to the first volume of the observatory's Annals.

17. A. E. Douglass, "Notice to the Citizens of Flagstaff," March 29, 1895, Lowell Observatory Archives.

18. Lowell, "Detection of Venus' Rotation Period and Fundamental Physical Features of the Planet's Surface," Popular Astronomy 4 (1896): 281--285; "Determination of Rotation Period and Surface Character of the Planet Venus," Monthly Notices of the Royal Astronomical Society 57 (1897): 148--149; "The Rotation Period of Venus," Astronomische Nachrichten, no. 3406 (1897): 361--364; "Venus in the Light of Recent Discoveries," Atlantic Monthly 5 (1897): 327--343.

19. Lowell, Boston Evening Transcript, November 28, 1896.

20. Lowell, "Mascari, Cerulli and Schiaparelli on Venus' Rotation Period," Popular Astronomy 4 (1897): 389.

21. E. M. Antoniadi, "On the Rotation of Venus," Journal of the British Astronomical Association 8 (1897): 46.

22. P. Lowell, "Means, Methods, and Mistakes in the Study of Planetary Evolution" (unpublished manuscript dated April 13, 1905, Lowell Observatory Archives).

23. See Andrew T. Young, "Seeing and Scintillation," Sky & Telescope 42 (1971): 139--141, at p. 150.

24. Douglass's most important work had been as Pickering's understudy in Arequipa, in which role he had begun his studies of atmospheric "seeing." See Douglass, "Atmosphere, Telescope, and Observer," Popular Astronomy 5 (1897): 64--84; also P. Lowell, "Atmosphere: In Its Effect on Astronomical Research" (lecture text, ca. spring 1897, Lowell Observatory Archives).

25. W. S. Adams to E. E. Barnard, October 29, 1905, Vanderbilt University Archives.

26. Douglass to W. L. Putnam, March 12, 1901, Andrew Ellicott Douglass Papers, Special Collections, University of Arizona Library.

27. Douglass's later career is described in George Ernest Webb, Tree Rings and Telescopes: The Scientific Career of A. E. Douglass (Tucson: University of Arizona Press, 1983). In his work with tree rings, Douglass thought that he could see evidence of eleven-year sunspot cycles. This aspect of his work was finally refuted by Valmore LaMarche and Harold Fitts, working at Douglass's Laboratory of Tree-Ring Research, in 1972. John A. Eddy noted in his review of Webb's book that "the ultimate irony of Douglass's later life [was] in succumbing to the same faults of autosuggestion that he had diagnosed in Lowell not that many years before" (Journal for the History of Astronomy 17 [1986]: 69--71).

28. Lowell, "The Markings on Venus," Astronomische Nachrichten, no. 3823 (1902): 129--132, at p. 130.

29. Lowell, "Venus---1903," Popular Astronomy 12 (1904): 184--190, at p. 185.

30. Lowell, "Epitome of Results at the Lowell Observatory April 1913--April 1914," Lowell Observatory Bulletin, no. 59 (1914).

31. E. Walter Maunder and J. E. Evans, "Experiments as to the Actuality of the `Canals' of Mars," Monthly Notices of the Royal Astronomical Society 58 (1903): 488--499, at p. 498.

32. "Report of the Meeting of the Association Held on Dec. 30, 1903," Journal of the British Astronomical Association 14 (1904): 118.

33. Antoniadi, "Report of Mars Section, 1896," Memoirs of the British Astronomical Association 6 (1898): 55--102, at, p. 62.

34. Antoniadi, "Report of Mars Section, 1903," Memoirs of the British Astronomical Association 16 (1910): 55--104, at p. 58.

35. P. B. Molesworth, manuscript in Royal Astronomical Society Archives.

36. For accounts of Cerulli's career, see Mentore Maggini, "Vincenzo Cerulli," Memorie de la Societa Astronomica Italiana 4 (1927): 171--187; and Luigi Prestinenza, "Vincenzo Cerulli e la sua Collis Uraniae," L'Astronomia (October 1989): 25--28.

37. V. Cerulli, Marte nel 1896--97 (Collurania, 1898), p. 105.

38. Schiaparelli, Corrispondenza su pianeta Marte, 2 vols. (Pisa: Domus Galilaeana, 1976), vol. 2, p. 307.

39. P. Lowell, Mars as the Abode of Life (New York: Macmillan, 1910), pp. 181--182.

40. P. Lowell, Mars and Its Canals (New York: Macmillan, 1906), p. 126.

41. Quoted in P. Lowell, Mars as the Abode of Life, p. 155. This was less an endorsement than it seemed, however, for Schiaparelli wrote to Antoniadi on August 29, 1909: "Perhaps over a longer or shorter period, molecular actions develop inside the images, in spite of their being fixed---or even during the fixing---and these actions follow different images of the same object, even when the photographs are taken under conditions and circumstances which are apparently identical, and in the same series. All in all, the problem of the photography of Mars is beset with traps and difficulties" (quoted in E. M. Antoniadi, The Planet Mars, trans. Patrick Moore [Shaldon Devon, U.K.: Keith Reid, 1975], p. 262).

42. P. Lowell, Mars and Its Canals, p. 277.

43. See W. H. Wesley, "Photographs of Mars," Observatory 28 (1905): 314; and H. H. Turner, "From an Oxford Note-book," Observatory 28 (1905): 336.

44. A. R. Wallace, Is Mars Habitable? (London: Macmillan, 1907).

45. Lowell, "A General Method for Evaluating the Surface-Temperature of the Planets; with Special Reference to the Temperature of Mars," Philosophical Magazine, ser. 6, 14 (July 1907): 161--176.

46. Wrote Wallace: "The figure he uses in his calculations for the actual albedo of the earth, 0.75, is also not only improbable, but almost self-contradictory, because the albedo of cloud is 0.72, and that of the great cloud-covered planet, Jupiter, is given by Lowell as 0.75, while Zollner made it only 0.62. Again, Lowell gives Venus an albedo of 0.92, while Zollner made it only 0.50 and Mr. Gore 0.65. This shows the extreme uncertainty of these estimates, while the fact that both Venus and Jupiter are wholly cloud-covered, while we are only half-covered, renders it almost certain that our albedo is far less than Mr. Lowell made it. It is evident that mathematical calculations founded upon such uncertain data cannot yield trustworthy results. But this is by no means the only case in which the data employed in this paper are of uncertain value. . . . It requires a practiced mathematician, and one fully acquainted with the extensive literature of this subject, to examine these various data, and track them through the maze of formulae and figures so as to determine to what extent they affect the final result" (Is Mars Habitable, p. 51).

47. Ibid., p. 20.

48. Wrexie Louise Leonard, Percival Lowell: An Afterglow (Boston: Badger Press, 1921), p. 25. The lectures were serialized in Century magazine, and in 1910 were published in book form as Mars as the Abode of Life.

49. Lowell to D. P. Todd, July 26, 1907, Lowell Observatory Archives.

Chapter 9. Opposition 1909

1. V. Cerulli, "Polemica Newcomb-Lowell-fotografie lunari," Rivista di astronomia 2 (1908): 13--23, at p. 13. My thanks to Signor Luigi Prestinenza for bringing this letter to my attention.

2. G. V. Schiaparelli to E. M. Antoniadi, December 15, 1909, quoted in E. M. Antoniadi, La planète Mars, 1659--1929 (Paris: Hermann et Cie, 1930), p. 31.

3. "G. Schiaparelli über die Marstheorie von Svante Arrhenius," Kosmos 7 (1910): 303.

4. W. W. Campbell to G. E. Hale, May 11, 1908, Mary Lea Shane Archives of the Lick Observatory.

5. P. Lowell to V. M. Slipher, March 16, 1908, Lowell Observatory Archives.

6. W. W. Campbell to G. E. Hale, May 11, 1908, Mary Lea Shane Archives of the Lick Observatory.

7. W. W. Campbell, "Water Vapor in the Atmosphere of the Planet Mars," Science 30 (1909): 474--475.

8. See Donald E. Osterbrock, "To Climb the Highest Mountain: W. W. Campbell's 1909 Mars Expedition to Mount Whitney," Journal for the History of Astronomy 20 (1989): 77--97.

9. P. Lowell, "The Canals---I," Popular Astronomy 2 (1895): 258.

10. See Donald E. Osterbrock, Pauper and Prince: Ritchey, Hale and Big American Telescopes (Tucson: University of Arizona Press, 1993), pp. 89--91.

11. For biographical information on Antoniadi, see Richard McKim, "The Life and Times of E. M. Antoniadi, 1870--1944," Journal of the British Astronomical Association 103 (1993): 164--170, 219--227.

12. E. M. Antoniadi, "Report of Mars Section, 1896," Memoirs of the British Astronomical Association 5 (1897): 82.

13. Ibid.

14. Ibid., p. 83.

15. Ibid., p. 85.

16. For further information about Brenner's strange personality and career, see Joseph Ashbrook, "The Curious Career of Leo Brenner," The Astronomical Scrapbook (Cambridge, Mass.: Sky Publishing, 1984), pp. 103--111; Michael Heim, Spiridion Gop_evi_: Leben und Werk (Wiesbaden: O. Harrassowitz, 1966); and for a more sympathetic view, Martin Stangl, "The Forgotten Legacy of Leo Brenner," Sky & Telescope 90 (1995): 100--102.

17. Antoniadi, "Report of Mars Section, 1898--1899," Memoirs of the British Astronomical Association 9 (1901): 68.

18. Antoniadi, 1898, quoted in C. Flammarion, La planète Mars, et ses conditions d'habitabilité, 2 vols. (Paris: Gauthier-Villars et Fils, 1909), vol. 2, pp. 410--411; and 1902, in John Burnett, "British Studies of Mars: 1877--1914," Journal of the British Astronomical Association 89 (1979): 136--145, at p. 139.

19. McKim, "The Life and Times of E. M. Antoniadi," p. 168.

20. Antoniadi, "Report of the Mars Section, 1900--1901," Memoirs of the British Astronomical Association 11 (1903): 137.

21. Antoniadi, "Report of Mars Section, 1903," Memoirs of the British Astronomical Association 16 (1910): 225--274.

22. E. W. Maunder, "A New Chart of Mars," Observatory 26 (1903): 351.

23. Antoniadi, "Note on Mr. Lowell's Drawings of Mars," Journal of the British Astronomical Association 20 (1909): 42--43, at p. 43.

24. P. Lowell to E. M. Antoniadi, September 26, 1909, Lowell Observatory Archives.

25. According to the work of A. Kolmogoroff, the energy contained in a turbulent eddy is proportional to the five-thirds power of its linear size. Since the squares of the refractive index fluctuations are proportional to the kinetic energies of the eddies, the refractive index fluctuations are very nearly proportional to the eddy sizes. See Andrew T. Young, "Seeing and Scintillation," Sky & Telescope 42 (1971): 139.

26. Antoniadi, "Fourth Interim Report for the Apparition of 1909," Journal of the British Astronomical Association 20 (1909): 78--81, at p. 79.

27. Antoniadi, "On the Advantages of Large over Small Telescopes in Revealing Delicate Planetary Detail," Journal of the British Astronomical Association 21 (1910): 104--106, at p. 105.

28. Antoniadi to P. Lowell, October 9, 1909, Lowell Observatory Archives.

29. Antoniadi to W. H. Wesley, September 25, 1909, Royal Astronomical Society Archives. In another letter, to Barnard, dated December 11, 1909, he deleted the terrestrial analogy, writing simply: "I have seen a few straight, or even parallel lines, but then I was careful to note that such impressions were fleeting . . . and that, whenever definition was quite satisfactory, all such appearances vanished, the face of the planet looking like that of the Moon" (Vanderbilt University Archives).

30. Antoniadi to P. Lowell, October 6, 1909, Lowell Observatory Archives.

31. P. Lowell to E. M. Antoniadi, November 2, 1909, Lowell Observatory Archives.

32. Antoniadi to P. Lowell, November 15, 1909, Lowell Observatory Archives.

33. Antoniadi later felt the need to defend his priority in having seen what a large telescope could show on Mars, pointing out that his first report on his Meudon observations of September 20 had been published eight days before the famous telegram of Edwin B. Frost, director of the Yerkes Observatory, who had answered a question about the success of the Yerkes refractor in showing the canals by wiring: "Yerkes telescope too powerful for canals." Observations similar to Antoniadi's were made by George Ellery Hale and a group at Mount Wilson (including Lowell's former assistant Douglass) using the 60-inch (1.52-m) reflector diaphragmed to 44 inches (1.12 m) to decipher so much detail on the planet that they found it impossible to draw.

34. Antoniadi, "Fourth Interim Report," Journal of the British Astronomical Association 20 (1909): 79.

35. Antoniadi, "Fifth Interim Report," Journal of the British Astronomical Association 20 (1909): 137.

36. Antoniadi, "Le retour de la planète Mars," Bulletin Société Astronomique de France 40 (1926): 348--349.

37. Antoniadi, "Considerations on the Physical Appearance of the Planet Mars," Popular Astronomy 21 (1913): 420.

38. P. Lowell, "Our Solar System," Popular Astronomy 24 (1916): 427.

39. Antoniadi, "Second Interim Report on the Observations of 1909," Journal of the British Astronomical Association 20 (1909): 28.

40. H. G. Wells, The War of the Worlds (New York: Harper, 1898). A Princess of Mars, by Edgar Rice Burroughs, was first published in All-Story Magazine as a six-part serial, February through July 1912; it appeared in book form in 1917. It was the first of Burroughs's Martian tales, followed by The Gods of Mars (1918), The Warlord of Mars (1919), Thuvia, Maid of Mars (1920), The Chessmen of Mars (1922), The Master Mind of Mars (1928), A Fighting Man of Mars (1931), Swords of Mars (1936), Synthetic Men of Mars (1940), and Llana of Gathol (1948).

Chapter 10. The Lingering Romance

1. Howard Plotkin, "William H. Pickering in Jamaica: The Founding of Woodlawn and Studies of Mars," Journal for the History of Astronomy 24 (1993): 101--122. Pickering died a bitter man in 1938 because he felt that his contributions to astronomy had not been appreciated (Walter H. Haas to William Sheehan, personal correspondence, May 31, 1994).

2. Quoted in Richard McKim, "The Life and Times of E. M. Antoniadi, 1870--1944. Part 2: The Meudon Years," Journal of the British Astronomical Association 103, no. 5 (1993): 219--227, at p. 223.

3. E. C. Slipher, The Photographic Story of Mars (Flagstaff, Ariz.: Northland Press, 1962).

4. E. M. Antoniadi, La planète Mars, 1659--1929 (Paris: Hermann et Cie, 1930); it has been translated into English by Patrick Moore as The Planet Mars (Shaldon Devon, U.K.: Keith Reid, 1975).

5. McKim, "The Life and Times of E. M. Antoniadi, 1870--1944. Part 2: The Meudon Years."

6. H. P. Klein, N. H. Horowitz, and K. Biemann, "The Search for Extant Life on Mars," in Mars, ed. H. H. Kieffer, B. M. Jakosky, C. W. Snyder, and M. S. Matthews (Tucson: University of Arizona Press, 1993), p. 1223.

7. P. Lowell, Mars as the Abode of Life (New York: Macmillan, 1908), p. 240.

8. G. de Vaucouleurs, Physics of the Planet Mars, trans. Patrick Moore (London: Faber and Faber, 1954).

9. W. S. Adams and T. Dunham, "The B Band of Oxygen in the Spectrum of Mars," Astrophysical Journal 79 (1934): 308--316; idem, "Water-Vapor Lines in the Spectrum of Mars," Publications of the Astronomical Society of the Pacific 49 (1937): 209--211.

10. G. de Vaucouleurs, The Planet Mars, trans. Patrick Moore (London: Faber and Faber, 1950), p. 127.

11. E. M. Antoniadi, The Planet Mars, p. 54.

12. Ibid.

13. E. M. Antoniadi, "Mars Report, 1909," Memoirs of the British Astronomical Association 20 (1915): 37.

14. Slipher, The Photographic Story of Mars, p. 39.

15. Ibid.

16. T. E. Thorpe, "Viking Orbiter Observations of the Mars Opposition Effect," Icarus 36 (1978): 204--215.

17. P. Lowell, Mars and Its Canals, pp. 39--40.

18. G. de Vaucouleurs, The Planet Mars, p. 26.

19. Alfred Russel Wallace, Is Mars Habitable? (London: Macmillan, 1907), pp. 34--35.

20. Quoted in Samuel Glasstone, The Book of Mars (Washington, D.C.: National Aeronautics and Space Administration, 1968), p. 104.

21. G. Fournier, quoted in de Vaucouleurs, The Planet Mars, p. 63.

22. Antoniadi, The Planet Mars, p. 27.

23. Ibid., p. 29.

24. E. E. Barnard, observing notebook, Yerkes Observatory Archives.

25. G. P. Kuiper, "Visual Observations of Mars, 1956," Astrophysical Journal 125 (1957): 307--317.

26. D. G. Rea, B. T. O'Leary, and W. M. Sinton, "The Origin of the 3.58- and 3.69-Micron Minima in the Infrared Spectra," Science 147 (1965): 1286--1288.

27. M. E. Chevreul, The Principles of Harmony and Contrast of Colours, 3d ed., trans. Charles Martel (London, 1860).

28. Ibid., p. 11.

29. Dean B. McLaughlin, "Volcanism and Aeolian Deposition on Mars," Geological Society of America Bulletin 65 (1954): 715--717; McLaughlin, "Interpretation of Some Martian Features," Publications of the Astronomical Society of the Pacific 66 (1954): 161--170; McLaughlin, "Wind Patterns and Volcanoes on Mars," Observatory 74 (1954): 166--168; McLaughlin, "Further Notes on Martian Features," Publications of the Astronomical Society of the Pacific 66 (1954): 221--229; McLaughlin, "Additional Evidence of Volcanism on Mars," Bulletin of the American Geological Society 66 (1955): 769--772; McLaughlin, "Changes on Mars, as Evidence of Wind Deposition and Volcanism," Astronomical Journal 60 (1955): 261--270; McLaughlin, "The Volcanic-Aeolian Hypothesis of Martian Features," Publications of the Astronomical Society of the Pacific 68 (1956): 211--218; McLaughlin, "A New Theory of Mars," Michigan Alumnus Quarterly Review 62 (1956): 301--307.

30. T. Saheki, "Martian Phenomena Suggesting Volcanic Activity," Sky & Telescope 14 (1955): 144--146.

31. Interestingly, other flares with associated clouds were noted here by S. Tanabe on November 6, 1958, and by S. Fuikui on November 10, which led Charles Capen to suspect that the region might be actively volcanic at the present time (Capen, unpublished manuscript). Some of the Viking 1 orbiter images revealed a cloud that cast a shadow of unusual shape that was consistent with an eruption, and was tentatively identified by Leonard Martin of the Lowell Observatory as a steam vent; it is located at 79° W, 16° S, between Solis Lacus and Tithonius Lacus, near the location where the Japanese observers recorded their flares.

32. G. P. Kuiper, "Note on Dr. McLaughlin's Paper," Publications of the Astronomical Society of the Pacific 68 (1956): 304--305.

33. Kuiper, "Visual Observations of Mars, 1956."

34. Quoted in Glasstone, The Book of Mars, p. 119.

35. Tombaugh's view is that "the Martian canals were global fracture fault lines, perhaps induced by internal heating and expansion, bursting a thick rigid crust at the round spots known as oases, or triggered by asteroid impacts at the round spots known as oases" (Clyde W. Tombaugh to William Sheehan, personal correspondence, December 6, 1986--March 9, 1987). For the suggestions of Baldwin and Öpik, see Ralph B. Baldwin, The Face of the Moon (Chicago: University of Chicago Press, 1949); and E. J. Öpik, "Collision Probabilities with the Planets," Proceedings of the Royal Irish Academy 54A (1951): 165--199. Among others who recognized that a flat Mars did not follow from the apparently smooth terminator was V. A. Firsoff, who wrote in Our Neighbour Worlds (London: Hutchinson, 1952), p. 23: "On the Moon five-power binoculars will reveal a wealth of detail, but if her phase is full the mountains will not stand out clearly, as they cast no visible shadows. This is how we see Mars at opposition through the most powerful telescopes. . . . Moreover, Mars has a sensible atmosphere, and, although this is remarkably transparent, it does intervene, especially at the limb or terminator, where accidents of the terrain will show best. To sum up, it is perhaps not very significant that no mountains or marked differences in altitude of the ground have been discovered on Mars by direct observation, and our estimates of heights and depressions on his surface must needs be somewhat problematic."

36. A. Dollfus, "Mèsure de la quantité de vapeur d'eau contenue dans l'atmosphere de la planète Mars," Comptes Rendu Académie Sciences 256 (1963): 3009--3011; H. Spinrad, G. Münch, and L. D. Kaplan, "The Detection of Water Vapor on Mars," Astrophysical Journal 137 (1963): 1319--1321.

37. L. D. Kaplan, G. Münch, and H. Spinrad, "An Analysis of the Spectrum of Mars," Astrophysical Journal 139 (1964): 1--15.

Chapter 11. Spacecraft to Mars

1. A. J. Kliore, D. L. Cain, G. S. Levy, V. R. Eshleman, G. Fjeldbo, and F. D. Drake, "Occultation Experiment: Results of the First Direct Measurement of Mars' Atmosphere and Ionosphere," Science 149 (1965): 1243--1248.

2. R. B. Leighton and B. C. Murray, "Behavior of Carbon Dioxide and Other Volatiles on Mars," Science 153 (1966): 136--144. Leighton and Murray calculated that, for a moonlike Mars---that is, one without condensible gases---the temperature would fall well below -128°C in the polar regions, and predicted the existence of permanent caps of frozen carbon dioxide.

3. R. B. Leighton et al., Mariner Mars 1964 Project Report: Television Experiment. Part I: Investigators' Report (Jet Propulsion Laboratory Technical Report 32-884, part I, 1967).

4. See E. M. Shoemaker, "Impact Mechanics at Meteor Crater," in The Moon, Meteorites and Comets, ed. B. M. Middlehurst and G. P. Kuiper (Chicago: University of Chicago Press, 1963), 301--336. For historical background on this particular issue, see W. G. Hoyt, Coon Mountain Controversies (Tucson: University of Arizona Press, 1987).

5. See Don E. Wilhelms, To a Rocky Moon (Tucson: University of Arizona Press, 1993).

6. J. E. Mellish, letter, Sky & Telescope 31 (1966): 339. His letter of January 18, 1935, to Walter Leight describing his observations was published by Rodger W. Gordon, "Mellish and Barnard---They Did See Martian Craters!" Journal of the Association of Lunar and Planetary Observers 29 (1975): 196--199.

7. The literature on this subject has grown rather extensive. See, for instance, Rodger W. Gordon, "Martian Craters from Earth," Icarus 29 (1976): 153--154; "Craters on Mars and Mercury: A History of Predictions and Observations," in Yearbook of Astronomy, ed. P. Moore (London, 1982), pp. 138--155; R. J. McKim, note, Journal of the British Astronomical Association 97 (1987): 191--192; William Sheehan and Richard McKim, "The Myth of Earth-Based Martian Crater Sightings," Journal of the British Astronomical Association 104 (1994): 281--286; and Richard McKim and William Sheehan, "Visibility of Martian Craters from Earth," Journal of the British Astronomical Association 105 (1995): 137.

8. Thomas A. Mutch, Raymond E. Arvidson, James W. Head III, Kenneth L. Jones, and R. Stephen Saunders, The Geology of Mars (Princeton: Princeton University Press, 1976), p. 17.

9. D. G. Rea, "Evidence for Life on Mars," Nature 200 (1964): 114--116; C. Sagan and J. B. Pollack, "A Windblown Dust Model of Martian Surface Features and Seasonal Changes," Smithsonian Astrophysical Observatory Special Report 255 (1967); and Sagan and Pollack, "Windblown Dust on Mars," Nature 223 (1969): 791--794.

10. C. F. Capen, The Mars 1964--1965 Apparition, Jet Propulsion Laboratory Technical Report 32-990.

11. C. F. Capen to W. Sheehan, personal communication, April 24, 1983.

Chapter 12. Mariner 9

1. C. R. Chapman, J. B. Pollack, and C. Sagan, An Analysis of the Mariner 4 Photographs of Mars, Smithsonian Astrophysical Observatory Special Report 268 (Washington, D.C., 1968).

2. C. F. Capen, "Martian Yellow Clouds---Past and Future," Sky & Telescope 41 (1971): 117--120, at p. 120.

3. An intriguing record of what several prominent personalities in planetary astronomy and science fiction expected to find is in Ray Bradbury, Arthur C. Clarke, Bruce Murray, Carl Sagan, and Walter Sullivan, Mars and the Mind of Man (New York: Harper and Row, 1973).

4. For detailed discussions, see Thomas A. Mutch, Raymond E. Arvidson, James W. Head III, Kenneth L. Jones, and R. Stephen Saunders, The Geology of Mars (Princeton: Princeton University Press, 1976); Michael H. Carr, The Surface of Mars (New Haven: Yale University Press, 1981); Victor R. Baker, The Channels of Mars (Austin: University of Texas Press, 1982); Peter Cattermole, Mars: The Story of the Red Planet (London: Chapman and Hall, 1992); and Hugh H. Kieffer, Bruce M. Jakosky, Conway W. Snyder, and Mildred S. Matthews, eds., Mars (Tucson: University of Arizona Press, 1993).

5. J. M. Boyce, A Method for Measuring Heat Flow in the Martian Crust Using Impact Crater Morphology, NASA TM-80339 (Washington, D.C., 1979), pp. 114--118.

6. The scale height over which the barometric pressure is reduced by a factor of 1/e (where e is the base of natural logarithms, or approx. 2.72), is on the order of 10 kilometers.

7. D. E. Wilhelms and S. W. Squyres, "The Martian Hemispheric Dichotomy May Be Due to a Giant Impact," Nature 309 (1984): 138--140.

8. V. R. Baker, The Channels of Mars (Austin: University of Texas Press, 1982).

9. V. C. Gulick and V. R. Baker, "Fluvial Valleys and Martian Paleoclimates," Nature 341 (1989): 514--516.

10. V. R. Baker and D. J. Milton, "Erosion by Catastrophic Floods on Mars and Earth," Icarus 23 (1974): 27--41.

Chapter 13. Vikings---and Beyond

1. Viking Orbiter Imaging Team, Viking Orbiter Views of Mars, NASA SP-441 (Washington, D.C., 1980), p. 4.

2. Four spacecraft (two orbiters and two landers) were launched during summer 1973 and arrived at Mars between February 10 and March 12, 1974. Unfortunately, none worked entirely as planned. The braking rocket of the first orbiter, Mars 4, failed to fire, and it merely swept past Mars and returned a few television images, none very good. The other orbiter, Mars 5, did make it into orbit and managed to obtain photographs of which a few of the best were comparable in quality to those of Mariner 9, but it failed after only twenty-two orbits. As for the landers, the Mars 7 descent module separated prematurely and missed Mars altogether; Mars 6 did better, at least initially---the descent module separated successfully and transmitted data all the way down to the surface, but then contact was lost. After that, until the Phobos mission of 1989, the Russians concentrated their efforts on Venus instead of Mars, where they enjoyed one of their greatest triumphs in achieving the first successful soft landings on the surface of another planet with their Veneras 9 and 10, in October 1975.

3. The true color of the rocks is chocolate brown. See Andrew T. Young, "What Color Is the Solar System?" Sky & Telescope 69 (1985): 399--403.

4. Viking Imaging Team, The Martian Landscape, NASA SP-425 (Washington, D.C., 1978), p. 36.

5. Not everyone accepted the revised version, even at the time; see, for instance, V. A. Firsoff, The Solar Planets (Newton Abbot, U.K.: David and Charles, 1977), pp. 134--135.

6. See, for instance, the summaries provided by H. P. Klein, "The Viking Biological Experiments on Mars," Icarus 34 (1978): 666--674, and "The Viking Mission and the Search for Life on Mars," Review of Geophysics and Space Physics 17 (1979): 1655--1662; N. H. Horowitz, To Utopia and Back: The Search for Life in the Solar System (New York: Freeman, 1986).

7. See G. V. Levin and P. A. Straat, "Recent Results from the Viking Labeled Release Experiment on Mars," Journal of Geophysical Research 82 (1977): 4663--4668; Klein, "The Viking Biological Experiments on Mars"; G. V. Levin and P. A. Straat, "A Reappraisal of Life on Mars," in The NASA Mars Conference, ed. D. B. Reiber (San Diego: Univelt, Inc., for NASA and the American Astronautical Society, 1988), pp. 187--208.

8. K. L. Jones, S. L. Bragg, S. D. Wall, C. E. Carlston, and D. G. Pidek, "One Mars Year; Viking Lander Imaging Observations," Science 204 (1979): 799--806.

9. H. H. Kieffer, S. C. Chase, Jr., T. Z. Martin, E. D. Miner, and F. D. Palluconi, "Martian North Pole Summer Temperatures: Dirty Water Ice," Science 194 (1976): 1341--1344.

10. V. A. Firsoff, The Solar Planets, p. 141.

11. C. Sagan, J. Veverka, P. Fox, R. Dubisch, J. Lederberg, E. Levinthal, L. Quam, R. Tucker, J. B. Pollack, and B. A. Smith, "Variable Features on Mars: Preliminary Mariner 9 Television Results," Icarus 17 (1972): 346--372; see also Mariner Mars 1971, Project Final Report, Jet Propulsion Laboratory Technical Report 32-1550 (1973).

12. E. S. Barker, R. A. Schron, A. Woszcyk, R. G. Tull, and S. J. Little, "Mars: Detection of Atmospheric Water Vapor during the Southern Hemisphere Spring and Summer Season," Science 170 (1970): 1308--1310.

13. Certainly there are many instances of local obscurations, but nothing like the global storms in the earlier records. During the 1890s and early 1900s, Percival Lowell, who saw only one dust cloud during eleven years of observation, wrote in Mars and Its Canals (p. 89): "If we are uncertain of the precise character of the Martian climate, we know on the other hand a good deal about the Martian weather. A pleasing absence of it over much of the planet distinguishes Martian conditions from our own. That we can scan the surface as we do without practical interruption day in and day out proves the weather over it to be permanently fair. In fact a clear sky, except in winter, and in many places even then, is not only the rule, but the rule almost without exceptions. In the early days of Martian study cases of obscuration were recorded from time to time by observers, in which portions of the disk were changed or hidden as if clouds were veiling them from view. More modern observations fail to support this deduction, partly by absence of instances, partly by other explanation of the facts. Certainly the recorded instances are very rare."

14. For obliquities above 54°, the average yearly solar insolation becomes greater at the poles than at the equator (this is actually the case for Uranus, with obliquity 97.9°, and the Pluto-Charon system, with obliquity 118.5°).

15. A. W. Ward, "Climatic Variations on Mars. 1. Astronomical Theory of Insolation," Journal for Geophysical Research 84 (1974): 7934--7939.

16. O. B. Toon, J. B. Pollack, W. Ward, J. A. Burns, and K. Bilski, "The Astronomical Theory of Climatic Change on Mars," Icarus 44 (1980): 552--607; J. B. Pollack and O. B. Toon, "Quasi-Periodic Climate Changes on Mars: A Review," Icarus 50 (1982): 259--287; Bruce M. Cordell, "Mars, Earth, and Ice," Sky & Telescope 72 (1986): 17--22.

17. V. R. Baker, R. G. Strom, V. C. Gulick, J. S. Kargel, G. Komatsu, and V. S. Kale, "Ancient Oceans, Ice Sheets and the Hydrological Cycle on Mars," Nature 352 (1991): 589--594.

Chapter 14. The Hurtling Moons of Mars

1. Jonathan Swift, Gulliver's Travels (London, 1726), part 3, chapter 3.

2. See Owen Gingerich, "The Satellites of Mars: Prediction and Discovery," Journal for the History of Astronomy 1 (1970): 109--115.

3. B. P. Sharpless, "Secular Accelerations in the Longitudes of the Satellites of Mars," Astronomical Journal 51 (1945): 185--195.

4. I. S. Shklovskii and C. Sagan, Intelligent Life in the Universe (New York: Dell, 1967).

5. Joseph A. Burns, "Contradictory Clues as to the Origin of the Martian Moons," in Mars, ed. H. H. Kieffer, B. M. Jakosky, C. W. Snyder, and M. S. Matthews (Tucson: University of Arizona Press, 1993), 1283--1301.

6. See J. A. Burns, "On the Orbital Evolution and Origin of the Martian Moons," Vistas in Astronomy 22 (1978): 193--210; and, for a particularly lucid and provocative account, Tom Van Flandern, Dark Matter, Missing Planets and New Comets (Berkeley, Calif.: North Atlantic Books, 1993).

Chapter 15. Observing Mars

1. In this respect, the July 10, 1986, opposition was one of the worst possible, since despite the large apparent diameter (22² of arc) the planet was almost as far south as it can get---between -23° and -28°---throughout the prime observing window. On the other hand, conditions at the September 28, 1988, opposition were as favorable as they had been at any time since 1909---the apparent diameter was 23², and the planet lay close to the celestial equator so that an observer at mid-northern latitudes had to peer through only half as much air mass as was necessary in 1986.

2. Harold Hill to William Sheehan, personal correspondence, June 21, 1994.

3. Quoted in Richard McKim, BAA Mars Section Circular (London: British Astronomical Association, May 1994).

4. Harold Hill to William Sheehan, personal correspondence, June 21, 1994.

5. Shigemi Numazawa, "Using a CCD on the Planets," Sky & Telescope 83 (1992): 209--215.

6. According to amateur Mars observer Thomas Dobbins: "The still images contain anamorphic distortions (i.e., squares deformed into rectangles or trapezoids, circles into ellipses) induced by atmospheric turbulence, despite the extremely short exposures involved. . . . These distortions are further compounded by a poor signal-to-noise ratio." On the other hand, he noted that "when one views video pictures at rates above the threshold for `flicker fusion,' our eye-brain combination fills in parts of the picture that are missing for short intervals. . . . By filling in or `integrating' the scenes, we average out noise and smooth out incrementally displaced or distorted images" (Thomas Dobbins to William Sheehan, personal correspondence, February 17, 1995).

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