The Spokes of Venus: An Illusion Explained

Schiaparelli G. V. , “Considerazioni sul moto rotatario del pianeta Venere” (1890) in Opere , v (1890), 400–10.

During a surprise visit to a meeting of the British Astronomical Association in 1910, Lowell gave a brief talk that included the remark: “It has been said that the best Indian of all is the dead Indian, and so the most perfect aperture you can use is no aperture at all. Just as you get down to nothing, so your image will improve….” See Report on the meeting of the Association, March 30, 1910 , 287–9.

Percival Lowell , “Atmosphere: In its effects on astronomical research”, a manuscript c. 1897 in the Lowell Observatory Archives.

Percival Lowell , “The rotation period of Venus”, Astronomische Nachrichten , no. 3406 (1896), cols 364–6.

Percival Lowell , “Determination of the rotation and surface character of the planet Venus”, Monthly notices of the Royal Astronomical Society , lvii (1897), 146–51, p. 148.

Report of meeting of the Royal Astronomical Society, 13 November 1896, Observatory , xix (1896), 419–31, p. 420.

Antoniadi E. M. , “The rotation period of Venus”, Journal of the British Astronomical Association , viii (1897), 43–46.

Douglass A. E. , “The markings of Venus”, Monthly notices of the Royal Astronomical Society , lviii (1898), 382–5.

Edward Emerson Barnard notebook in the Yerkes Observatory Archives. Barnard later drew up an account of his visit to Flagstaff for the Lick Observatory astronomer Campbell W. W. entitled “Observations at the Lowell Observatory in May and June 1898” that is preserved in the Mary Lea Shane Archive of the Lick Observatory.

Ibid. Douglass described the shortcomings of Flagstaff as an observing site in “The effects of mountains on the quality of the atmosphere”, Popular astronomy , vii (1899), 355–64.

In 1958 Douglass confided to the telescope maker Thomas R. Cave that Flagstaff also had the best saloons of the sites he tested!.

Douglass Putnam , 12 March 1901 (University of Arizona Special Collections). Douglass's break with Lowell is recounted in George Ernest Webb , Tree rings and telescopes: The scientific career of A. E. Douglass (Tucson, 1983), 43–49.

Percival Lowell , “The markings on Venus”, Astronomische Nachrichten , no. 3823 (1902), cols 129–32.

Percival Lowell , “Venus in 1903”, Popular astronomy , xii (1904), 184–90, p. 186.

Percival Lowell , The evolution of worlds (New York, 1910), 79–82.

See Philip Stooke , “The earliest maps of Venus”, Sky & telescope , August 1992, 156–8, and Richard Baum , “Venus: The enigma of phase-locked cloud structure and the UV syndrome”, Journal of the British Astronomical Association , cviii/4 (1998), 216–19.

Denning W. F. , Telescopic work for starlight evenings (London, 1891), 151.

Joseph Ashbrook , “The problem of visual observations of Venus”, Sky & telescope , October 1957, 588.

This article was reprinted in Douglass A. E. , Amateur telescope making advanced (New York, 1937), 585–605.

Personal correspondence from Sherman Schultz to the authors, 4 June 2000.

Joseph Meurers , Astronomische Experimente (Berlin, 1956), 25–27.

William Sheehan Thomas Dobbins , “Lowell and the spokes of Venus”, Sky & telescope , July 2002, 99–103.

The authors are indebted to the Mount Vernon Ohio , eye-surgeon Roger H. Sherman M.D. Phillip Steffey Daytona Beach , Florida, for this explanation.