• DOI:10.1086/351668
• Corpus ID: 26512655

W. H. Pickering's Planetary Predictions and the Discovery of Pluto

@article{Hoyt1976WHP,
  title={W. H. Pickering's Planetary Predictions and the Discovery of Pluto},
  author={William Graves Hoyt},
  journal={Isis},
  year={1976},
  volume={67},
  pages={551 - 564}
}

• W. Hoyt
• Published 1 December 1976
• Physics, Geology
• Isis

C ERTAINLY THE MOST PROLIFIC POSTULATOR of undiscovered planets in the annals of astronomy was Harvard's William Henry Pickering (1858-1938). While other serious planet hunters of his time were content with predictions of one or two possible trans-Neptunian bodies, Pickering populated the solar system beyond the asteroids with at least seven hypothetical planets, their distances ranging from 5.79 to 6,250 times that of the earth from the sun, and their masses from 0.045 to 20,000 earth masses. Pickering designated his seven planets 0, P, Q, R, S, T, and U, and in the years from 1909 to 1932 he published more or less complete sets of orbital elements for six of them (see Table 1). Only planet T, proposed in 1931 and almost immediately abandoned as being of doubtful reality, was left swinging in an unspecified orbit some 32.8 astronomical units from the sun.' His planet O-or more properly his planets 0, for surely there were two of them-was a short-lived rival to the planet X of Percival Lowell (1855-1916) in the controversy that followed the discovery of Pluto in 1930 at the Lowell Observatory in Flagstaff, Arizona. Pickering's long and productive career in astronomy began in 1883 when he became associated with Harvard College Observatory, then under the direction of his brother, Edward Charles Pickering (1846-1919). For the next forty years he distinguished himself primarily by his pioneering investigations into the problems of astronomical "seeing" and by his studies of Mars, the other planets, and their satellites. In 1889, for example, he was the first to test Mount Wilson in California as an astronomical site, and he also established observing stations for Harvard in 1891 at Arequipa, Peru, and in 1900 at Mandeville, Jamaica, in the British West Indies. In 1899 he discovered Saturn's ninth satellite, Phoebe, on photographic plates exposed at Arequipa by Harvard's Solon I. Bailey. Phoebe, which caused some stir because of its nondirect revolution around the ringed planet, turned out to be Pickering's only undisputed addition to the solar system.2