(b. Boston, Massachusetts, 13 March 1855; d. Flagstaff, Arizona, 12 November 1916)
More than any other astronomer of his generation, Percival Lowell had a profound influence on the general public. His thesis that the planet Mars was the abode of intelligent life continued to excite the public mind decades after his death; although the idea never gained the acceptance of his colleagues, it was not until after the Mariner flights to Mars during the late 1960’s that it could firmly and finally be banished from all consideration.
Lowell’s name is also forever linked with Pluto; although he did not live to see that distant planet (and while subsequent evidence has revealed its discovery to be accidental), there is no doubt that his inspiration advanced the date of its detection by many years. His most important contribution to astronomy, however, was his realization that superior observational work can be conducted only where atmospheric conditions are superior. He was a pioneer in constructing an observatory far from the lights and smoke of civilization.
Lowell was descended from some of the most prominent New England families. His father, Augustus Lowell, was closely identified with the cultural life of Boston. His mother, Katharine Bigelow Lawrence, was the daughter of Abbott Lawrence, sometime United States minister to Great Britain. A great great-grandfather, John Lowell, was a member of the Continental Congress; his son, Lowell’s great-grandfather, also John Lowell, represented Boston in the Massachusetts legislature. Both were actively interested in horticulture, and the younger John Lowell had on his farm some of the first greenhouses in the United States to be built on truly scientific principles. John Amory Lowell, Lowell’s grandfather, collected a valuable herbarium and botanical library, the latter now forming an important part of the Gray Herbarium. Lowell’s younger brother, Abbott Lawrence Lowell, became president of Harvard University: and his youngest sister, Amy Lowell, was well known as a poet and critic. James Russell Lowell, a first cousin of his father, was the foremost American man of letters of his time.
Lowell’s early schooling was at Miss Fetter’s dame school. He subsequently attended Noble’s School, where he developed interests in many fields, including astronomy. He graduated from Harvard University in 1876 with distinction in mathematics. After a year in Europe he went into his grandfather’s business (cotton mills and trust and utility companies) and in 1883 traveled to Japan to study its people, customs, and language. While in Japan he was invited to serve as foreign secretary and general counsellor to the first diplomatic mission from Korea to the United States. He subsequently visited Korea and wrote of his experiences there in Chosön—the Land of the Morning Calm—A Sketch of Korea (1885). For several years he journeyed throughout the Far East and learned much of the oriental character, which he portrayed in The Sound of the Far East (1888). Noto (1891) is a straightforward but exciting account of a trip to a remote part of Japan. An earlier interest in Shintoism was renewed by his visit to the sacred mountain of Ontake, and he described his studies of the Shinto trances in Occult Japan, or the Way of the Gods (1895).
But Lowell’s thoughts were turning more and more to astronomy, and on his final voyage to Japan he took a small telescope with him. He left the Orient for the last time in 1893. A favorable opposition of Mars was due toward the end of 1894, and Lowell resolved to study that planet then under the best possible conditions. At the 1877 opposition Mars had been extensively studied by Giovanni Sehiaparelli, whose widely publicized observations of the “canals” had opened a new era in the investigation of that planet. Lowell took up a suggestion by W. H. Pickering that the steadiest air in North America was to be found in the Arizona Territory, and as a result of tests in the spring of 1894 he selected an observing site on the eastern edge of the mesa to the west of Flagstaff, at an altitude of some 7,000 feet. He acquired an eighteen-inch and a twelve-inch telescope and began observations. In Mars (1895) Lowell concluded
…that the broad physical conditions of the planet are not antagonistic to some form of life; secondly, that there is an apparent dearth of water upon the planet’s surface, and therefore, if beings of sufficient intelligence inhabited it, they would have to resort to irrigation to support life; thirdly, that there turns out to be a network of markings covering the disk precisely counter-parting what a system of irrigation would look like; and, lastly, that there is a set of spots placed where we should expect to find the lands thus artificially fertilized, and behaving as such constructed oases should. All this, of course, may be a set of coincidences, signifying nothing; but the probability points the other way.
By 1896 Lowell had replaced the two borrowed telescopes with a twenty-four-inch telescope and had resumed observations of Mars by night and of Mercury and Venus by day. He had also tested sites in the Sahara and in Mexico and South America. During the winter of 1896-1897 he temporarily transferred his telescope to Tacubaya, Mexico, where it was believed—erroneously, as it turned out—that observing conditions would be better than in Flagstaff.
Overwork and insufficient sleep took their toll, and Lowell’s health broke down. He was kept from astronomy for four years, except for his participation in an eclipse expedition to Tripoli in 1900. Observations at the Lowell observatory continued, however, and the first two volumes of the observatory’s Annals appeared. Lowell was back in Flagstaff observing Mars in 1901, 1903, and 1905, and he expanded his earlier ideas about that planet inMars and Its Canals(1906) and Mars as the Abode of Life (1908). Lowell was not the first to regard the Martian bright areas as deserts and the dark areas as vegetation, but he studied in unprecedented detail the progressive “wave of darkening” of the dark areas, from pole to equator, as the seasons advanced from late winter, through spring, and into summer. As water was released from the melting polar caps, plant life would be revived; the accompanying increased prominence of the canals would indicate that water was flowing through them.
The premise that the dark areas are vegetation was almost universally accepted until the late 1950’s. Then astronomers began to suspect that the light and dark areas are equally barren, and that the changes in the latter are simply due to light-colored dust being blown across them by winds. Lowell had himself suggested that the polar caps were due to hoarfrost, although astronomers now believe them to arise more from solid carbon dioxide than from solidified water. Observations from the Mariner flights have confirmed the barren nature of the Martian surface. The canals exist, although not as the fantastic system of hundreds of straight lines depicted by Lowell; most, if not all, of them are in fact merely chance alignments of dark patches.
While it was Mars that received the greatest part of Lowell’s attention, he did not ignore the other planets. He “confirmed” Schiaparelli’s result that Mercury rotates on its axis in the same time it takes to orbit the sun, although radar studies have revealed the true rotation period to be only two-thirds as long. With V. M. Slipher he made, in 1911, the first reliable determination of the rotation period of Uranus—ten and three-quarter hours. He also made a critical investigation of the structure of Saturn’s rings, particularly when they were presented edgewise to the earth in 1907. And he made extensive studies of the “cloud formations’ on Jupiter.
A nonresident professor at the Massachusetts Institute of Technology, Lowell gave a series of lectures there in 1902, later published as The Solar System(1903). Another series of lectures there led to the publication of The Evolution of Worlds (1909). In the latter work, as in Mars as the Abode of Life, Lowell adopted the Chamberlin-Moulton hypothesis that the solar system arose as the result of the encounter of the sun and another star. He then discussed various stages in the evolution of a planet; as cooling set in, a crust formed, conditions became suitable for the development of life, and finally the oceans and atmosphere disappeared and life ceased. He supposed that Mars had evolved much more completely than the earth, and that the moon had reached its final stage. The Evolution of Worlds concludes with a vivid description of how life on the earth could end, as its inhabitants became aware of a dark star steadily approaching, finally to collide with the sun.
Lowell was also interested in purely theoretical studies of the solar system, and in particular that ofthe significance of the resonances among the planets. He maintained that, after each ofthe planets was formed, there Would be a tendency for the next one to collect at a point where its period of revolution bore some simple relationship to that of its predecessor: thus, after the formation of Jupiter, Saturn was formed with a period just two-and-a-half times longer; then Uranus with a period three times that of Saturn; and Neptune with a period twice as long again. There was a similar relationship among the periods of the inner planets.
The planets are not now observed to be exactly at these resonances, and Lowell discussed a mechanism whereby each planet was subsequently perturbed somewhat in toward the sun. Much of this theory is described in Lowell’s final book. The Genesis of the Planets (1916). The process cannot now be given serious consideration, but it led Lowell to anticipate the existence of another planet orbiting the sun with a revolution period twice that of Neptune. He had previously come to a similar conclusion by studying the distribution of the aphelion distances of the periodic comets; there are a large number of cometary aphelia near the orbit of Jupiter, a few near the orbits of Saturn and Uranus, several near that of Neptune, but apparently none in between.
The concept of “cometary families” has since been largely discredited (except for the Jupiter family), but more distant clusters of cometary aphelia could suggest the presence of at least one planet beyond Neptune. For the last eight years of his life Lowell paid particular attention to the problem of finding a trans-Neptunian planet. Recognizing that the orbit of Neptune was too imperfectly known for his purpose, he analyzed the residuals remaining between the observed and calculated positions of Uranus, as J. C. Adams and Le Merrier had done before him; this time, the perturbations by Neptune were taken into account. Lowell had C. O. Lampland photograph the region of the sky in which the new planet X was expected to lie. Subsequent refinement of the calculations led to considerable changes in the prediction, but X still eluded detection.
The search was continued at the Lowell observatory long after its founder’s death, and X was finally identified by Clyde Tombaugh in 1930. Named Pluto, with its symbol E depicting also the initials of Percival Lowell, the new planet was announced to the world on the seventy-fifth anniversary of Lowell’s birth. Pluto was found to travel in an orbit remarkably close to that predicted, although with a period only three-halves (not twice) that of Neptune. Pluto was considerably fainter than had been anticipated. Since it has now been established that Pluto has a mass scarcely greater than that of Mars (and possibly no greater than that of Mercury), it is quite clear that the discovery was due to an incredible coincidence.
Lowell married Constance Savage Keith in 1908. He was a brilliant speaker and was always in demand for lecture tours. He enjoyed all nature and derived from his ancestors a great love of botany. He found near Flagstaff a number of plants not previously known to prevail so far north, and he also discovered a new species of ash tree that now bears his name. Lowell was an honorary member of the Royal Astronomical Society of Canada, and he received medals from the national astronomical societies of France and Mexico.
1. Original Works. In addition to the books mentioned in the text many of Lowell’s writings are contained in the Annals of Lowell Observatory, 1-3 (1898-1905) and the Bulletin of Lowell Observatory, 1-2 (1903-1916). Other works include “On the Capture of Comets by Jupiter,” in Science, 15 (1902), 289; “Expedition for the Ascertaining of the Best Location of Observatories,” in Monthly Notices of the Royal Astronomical Society, 63 (1902), 42-43; “A Standard Scale for Telescopic Observations,” ibid., 63 (1902), 40-42; “On the Variable Velocity of Zeta Herculis in the Line of Sight,” in Astronomical Journal, 22 (1902), 190; “On the Kind of Eye Needed for the Detection of Planetary Detail,” in Popular Astronomy, 13 (1905), 92-94; and “Chart of Faint Stars Visible at the Lowell Observatory,” ibid., 391-392.
See also his “Comparative Charts of the Region Following Delta Ophiuchi,” in Monthly Notices of the Royal Astronomical Society, 66 (1905), 57; “Planetary Photography,” in Nature, 77 (1908), 402-404; “The Tores of Saturn,” in Popular Astronomy, 16 (1908), 133-146; “The Revelation of Evolution: A Thought and Its Thinker,” in Atlantic Monthly, 104 (1909), 174-183; “Planets and Their Satellite Systems,” in Astronomische Nachrichten, 182 (1909), 97-100; “The Plateau of the San Francisco Peaks in Its Effect on Tree Life,” in Bulletin of the American Geographical Society of New York (1909); “On the Limits of the Oblateness of a Rotating Planet and the Physical Deductions From Them,” in Philosophical Magazine, 6th ser., 19 (1910),710-712;“Saturn’s Rings,” in Astronomische Nachrichten, 184 (1910), 177-182; “The Hood of a Comet’s Head,” in Astronomical Journal, 26 (1910), 131-134; “On the Action of Planets Upon Neighboring Particles,” ibid., (1911), 171-174; and “Libration and the Asteroids,” ibid., 27 (1911), 41-46.
See also “The Sun as a Star,” in Popular Astronomy, 19 (1911), 283-287; “The Spectroscopic Discovery of the Rotation Period of Uranus,” in Observatory, 35 (1912), 228-230; “Sur la Désintégration des Cométes,” in Bulletin astronomique, 29 (1912), 94-100; “Precession and the Pyramids,” in Popular Science Monthly, 80 (1913), 449-460; “Precession of the Martian Equinoxes,” in Astronomical Journal, 28 (1914), 169-171; “Mimas and Enceladus,” in Popular Astronomy, 22 (1914), 633; “Memoir on a Trans-Neptunian Planet,” in Memoirs of the Lowell Observatory, 1, no. 1 (1915); “Memoir on Saturn’s Rings,” ibid., no. 2 (1915); “Measures of the Fifth Satellite of Jupiter Made at the Lowell Observatory in September 1915,” in Astronomical Journal, 29 (1916), 133—137; and “Our Solar System,” in Popular Astronomy, 24(1916), 419-427.
II. Secondary Literature. The most complete biographical information is to be found in A. L. Lowell, Biography of Percival Lowell (New York, 1935), and in an account issued by the Lowell Observatory and published in Popular Astronomy, 35 (1917), 219-223. L. Leonard, Percival Lowell: An Afterglow (Boston, 1921) is a delightful character sketch and contains many extracts from his letters.
For recent information on Mars, see S. Glasstone, The Book of Mars (Washington, D.C., 1968) and R. B. Leighton, N. H, Horowitz, B. C Murray, R. P. Sharp, A. G. Herriman, A. T. Young, B. A. Smith, M. E. Davies, and C. B. Leovy, “Mariner 6 Television Pictures: First Report,” in Science, 165 (1969), 684-690.
For material on Pluto and its discovery, 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; P. K. Seidelmann, W. J. Klepczynski, R. L. Duncombe, and E. S. Jackson, “Determination of the Mass of Pluto,” in Astronomical Journal, 76 (1971), 488-492; and C. W. Tombaugh, “Reminiscences of the Discovery of Pluto,” in Sky and Telescope, 19 (1960), 264-270.
Brian G. Marsden