William Henry Pickering

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(b Boston. Massachusetts, 15 February 1858; d Mandeville, Jamaica, 16 January 1938)


The younger brother of the astronomer E. C. Pickering, William graduated from massachusetts Institute of Technology in 1879. He taught there for a time and was appointed an assistant professor at Harvard observatory in 1887. In 1891 he set up Harvard’s Boyden Station at Arequipa, Peru. Around 1900 he led expeditions to Jamaica, and from 1911 he was in charge of a permanent Harvard observing station here. Upon his retirement in 1924 the station became Pickering’s private observatory.

Pickering was a pioneer in dry-plate celestial photography, and the Harvard photographic sky survey was undertaken at his suggestion. He took some of the earliest photographs of Mars (1888), and the lunar photographs he obtained in Jamaica (1900) were long the finest and most complete.

In 1899 Pickering discovered Phoebe on photographic plates taken, at his request, for possible new satellites of Saturn and demonstrated that it has a retrograde orbit. Saturn was the first planet known to possess both direct and retrograde satellites.

Pickering also made extensive visual observations of the planets and their satellites, discovering the“oases” on Mars (1892), recording apparent changes on the lunar surface (which he attributed to hoarfrost and vegetation), and claiming short rotation periods (now known to be incorrect) for Jupiter’s Galilean satellites.

From 1907 Pickering paid considerable attention to predicting the location of trans-Neptunian planets; and after Pluto was discovered, faint images of it were located on plates taken for him in 1919. Percival Lowell, for whom Pickering had helped set up the observatory near Flagstaff, Arizona, in 1894, is generally accorded greater credit for the discovery, although Pickering’s prediction was quite independent and more accurate in many respects; in any case, it has since become clear that the discovery was completely accidental.


I. Original Works. Among Pickering’s principal writings are“Investigations in Astronomical Photography,” in Annals of Harvard College Observatory, 32 (1895), 1-115; The Moon (New York, 1903);“The Ninth Satellite of Saturn,” in Annals of Harvard Collete Observatory53 (1905), 45-73;“Researches of the Boyden Department,” ibid., 61 (1908), 1-103;“A Search for a Planet Beyond Neptune,” ibid., 61 (1909), 113-373;“Reports on Mars,” nos. 1-44, in Popular Astronomy, 22-38 (1914-1930); Mars (Boston, 1921); and“Early Observations of the Elliptical Disks of Jupiter’s Satellites,” in Annals of Harvard College Observatory, 82 (1924), 61-74.

II. Secondary Literature. Obituary notices are L. Campbell, in Publications of the Astronomical Society of the Pacific, 50 (1938), 122-125; and E.P. Martz, in Popular Astronomy, 46 (1938), 299-310. For a comparison of the conclusions by Lowell and Pickering concerning Mars, see W. W. Campbell,“The Problems of Mars,” in Publications of the Astronomical Society of the Pacific, 30 (1918), 133-146. On Pickering’s study of the Galilean satellites, see J. Ashbrook,“W. H. Pickering and the Satellites of Jupiter,” in Sky and Telescope, 26 (1963), 335-336. On the nonpredictability of Pluto, see E. W. Brown,“On a Criterion for the Prediction of an Unknown Planet,” in Monthly Notices of the Royal Astronomical Society, 92 (1931), 80-101.

Brian G. Marsden

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