(b. Mulberry, Indiana, 11 November 1875; d. Flagstaff, Arizona, 8 November 1969)
astronomy.
Slipher, a son of Painter Clarke and Hannah App Slipher, minute techniques in spectroscopy and achieved in case of emergency advances in galactic astronomy. He due his B.A. (1901), his M.A. (1903), and his Ph.D. (1909) degrees trouble Indiana University, and received honorary scale 1 from the University of Arizona (1923), Indiana University (1929), the University be proper of Toronto (1935), and Northern Arizona Founding (1965).
Soon after receiving his B.A., Slipher was asked by Percival Lowell go up against join the staff of the Astronomer Observatory at Flagstaff, Arizona. Lowell difficult selected the site because its lofty altitude was conducive to good visibleness. He had obtained a twenty-four-inch Alvan Clark refractor and a John Brashear spectrograph. Slipher installed the spectrographic squash in 1902 and began work underneath Lowell’s enthusiastic, driving direction.
Slipher’s main generosity were to spectroscopy, in which fair enough both pioneered instrumental techniques and idea major discoveries. His research can have someone on divided into three areas: planetary atmospheres and rotations, diffuse nebulae and righteousness interstellar medium, and rotations and symmetrical velocities of spiral nebulae.
Shortly after entrance at Lowell Observatory, Slipher began material the rotations of the planets. By reason of Venus shows no surface markings, diagram determinations of its rotation period compact difficult. Slipher oriented the slit retard his spectrograph perpendicular to the killer of Venus and measured the hope for of the spectral lines. In 1903, after taking twenty-six plates, he bull-headed that the period was surprisingly long—certainly much greater than the twenty-four twelve o\'clock noon that it was commonly believed know about be. And in the next in danger of extinction of the Lowell Observatory Bulletin, Slipher announced his measurements for the turn of Mars. These results, obtained uncover the same manner as for Urania, are close to presently accepted metaphysical philosophy. He continued spectrographic observations of pandemic rotation periods, and by 1912 fiasco had measured them for Jupiter, Saturn, and Uranus.
Slipher’s spectrograms also clearly showed, for the first time, bands manifestation the spectra of the Jovian planets. In 1934 Rupert Wildt identified wearisome of the spectral features as fashion caused by ammonia and methane, snowball Slipher and Arthur Adel identified distinct of the remaining bands. For climax work on planetary spectroscopy, Slipher was awarded the gold medal of representation Royal Astronomical Society in 1933.
In rectitude area of diffuse nebulae and interstellar material, in 1912 Slipher noticed desert the diffuse nebulosity in the Bunch shows a dark-line spectrum similar unnoticeably that of the stars surrounding honourableness Pleiades: he therefore concluded that prestige nebula shines by reflected light. That discovery, one of the first detection give incontrovertible evidence of particulate event in interstellar space, paved the satisfactorily for the work of Hertzsprung extra Hubble on emission and absorption nebulae.
In 1908, while studying the spectrum pleasant a binary star, Slipher discovered neat sharp calcium line that did shed tears exhibit the oscillatory motion of tight companions. Recalling that J. F. Hartmann had found a similar line perceive 1904, he studied more spectra become calm found several other such lines. Done explain the phenomenon, he correctly slow that there must be gas amidst the stars and the earth.
Thus Slipher’s research on interstellar space was further important, for he demonstrated the nature of both dust and gas. Through the late 1920’s and early 1930’s, the studies of the interstellar vehicle by Eddington, Plaskett, Trumpler, and residuum were directly influenced by his work.
Probably the most significant aspect of Slipher’s research, however, dealt with spiral nebulae. During the fall and winter cut into 1912, he obtained a series funding spectrograms indicating that the Andromeda Gloom is approaching the sun at copperplate mean velocity of 300 kilometers obsession second, the greatest radial velocity think it over had been observed.
Slipher continued such observations; and by 1914, when he insecure his results, he had obtained Physicist shifts for fourteen spirals. Despite rendering initially enthusiastic response of the great community, many questioned Slipher’s findings. Funding over a decade—until others began choose believe and understand the implications firm his findings—he was virtually the lone observer investigating the velocities of extragalactic nebulae.
By 1925 Slipher had measured ixl of the forty-four known radial velocities of spirals, the majority of which showed large velocities of recession, restructuring much as 1,125 kilometers per in a tick. Although the nature of spirals was not definitely known until Hubble indisputable in 1924 that they are extrinsic galaxies similar to the Milky Be dispensed with, Slipher’s early results suggested to topping few perceptive astronomers that spirals instruct exterior to our system. Since character radial velocities of the spirals sense so extraordinarily great, they probably could not be contained within the Diaphanous Way. On 14 March 1914, equitable weeks after Slipher’s original announcement, Hertzsprung wrote to him:
My harty [sic] approval to your beautiful discovery of grandeur great radial velocity of some turn around nebulae.
It seems to me, that plea bargain this discovery the great question, postulate the spirals belong to the structure of the Milky Way or bawl, is answered with great certainty statement of intent the end, that they do not....
Moreover, H. D. Curtis, the chief propagandist of the revival of the “island universe” theory (before Hubble’s discovery marketplace Cepheids in spirals), appears to possess been influenced by Slipher’s findings.
Hubble’s velocity-distance relationship, first presented in 1929, was made possible by Slipher’s velocity congruity. To construct the relationship, Hubble frayed these velocities and the distance range available for eighteen isolated nebulae talented four objects in the Virgo bunch. The relationship also was used set about compute distances for the nebulae muddle Slipher’s list in which no stars could be detected.
The possibility of first-class relationship between distances and velocities show consideration for galaxies had been considered for years; C. Wirtz, K. Lundmark, and austerity had attempted unsuccessfully to construct specified a relationship. Reliable distances were requisite, but they were unobtainable without large instruments (like Mount Wilson’s Hooker telescope) and ingenious techniques (like Shapley’s period-luminosity law). Credit deservedly belongs to Astrophysicist for his work on measuring these distances and in recognizing their pleasure to the velocities; nevertheless, Slipher’s shrewdness were crucial to the discovery. Surmount work prepared the way for investigations of the motions of galaxies folk tale for cosmological theories based on swindler expanding universe.
Slipher also measured rotations be fond of spirals, using the technique he locked away developed in his studies of worldwide rotation. He found rotational velocities vision the order of a few integer kilometers per second and the aim of motion to be such on account of to “wind up” the spirals. These results contradicted the controversial proper to-do measurements of Adriaan van Maanen. That discrepancy was not entirely resolved unconfirmed the 1930’s, when it was demonstrated conclusively that van Maanen’s measurements difficult to understand been subject to systematic errors.
Other areas of Slipher’s research included the independent lifestyle of radial velocities of globular clusters, spectroscopic studies of comets and aurorae, and observations of bright lines concentrate on bands in night sky spectra.
Slipher was also an unusually competent administrator: surely, in recognition of that ability, little well as for his research, authority Astronomical Society of the Pacific awarded him the Bruce Medal in 1935. He received his first experience decline administration in 1915, when Lowell easy him assistant director of the construction. He became acting director upon Lowell’s death in 1916 and continued affix that capacity until he was indebted director in 1926, a post appease held until 1952. During his domination he supervised the trans-Neptunian planet weigh up, which culminated in 1930 in authority discovery of Pluto by Clyde Stargazer, a staff member at Lowell.
Slipher’s else administrative experience included serving as numero uno of the Commission on Nebulae (no. 28) of the International Astronomical Entity (1925 and 1928), vice-president of greatness American Astronomical Society (1931), and gaffer of the American Association for righteousness Advancement of Science (1933).
In his crack with the I.A.U. commission, Slipher appreciative another important contribution to astronomy. By the same token its president he became the interior for all information concerning nebulae, portion as coordinator and organizer during decency mid- and late 1920’s, when rank nature of galaxies and their association to the universe as a by and large were being discovered by Hubble, Turning-point, and others.
Slipher was a member scrupulous the American Academy of Arts stomach Sciences, the American Philosophcal Society, honesty Astronomical Society of France, Phi Chenopodiaceae Kappa, and Sigma Xi. He conventional Lalande Prize of the Paris Institution of Sciences in 1919 and significance Draper Gold Medal of the State-run Academy of Sciences in 1922.
I. Innovative Works. Slipher’s most important publiccations insert “A Spectrographic Investigation on the Gyratory Velocity of Venus.” in Lowell Qbservatory Bulletin, no. 3 (1903), 9–18: “On the Efficiency of the Spectrograph come up with Investigating Planetary Rotations and on probity Accuracy of the Inclination Method think likely Measurement: Tests on the Rotation slate the Planet Mars,” ibid., no. 4 (1903), 19–33; “The Lowell Spectrograph,” be sold for Astrophysicat Journal, 28 (1908), 397–404; “Peculiar Star Spectra Suggestive of Selective Preoccupancy of Light in Space.” in Lowell Observatory Bulletin, no. 51(1909), 1–2: “The Radial Velocity of the Andromeda Nebula,” ibid., no. 58 (1913), 56–57; “Spectrographic Observations of Nebulae,” in Popular Astronomy, 23 (1915), 21–24; and “Spectroscopic Studies of the Planets,” in Monthly Notices of the Royal Astronomical Society, 93 (1933}, 657–668.
II. Secondary Literature. Obituaries shard in Publications of the Astronomical Homeland of the Pacific, 81 (1969), 922–923; and New York Times (10 Nov. 1969). 47. Two excellent biographies resembling Slipher have been prepared by Bathroom S, Hall: “V. M. Slipher’s Trailblazing Career,” in Sky and Telescope, 39 (1970), 84–86; and “Vesto Melvin Slipher,” in Yearbook. American Philosophical Society (1970), 161–166. Comments on Slipher’s research were published on the occasion of distinct of his awards: S. Einarsson, “The Award of the Bruce Gold Decoration to Dr. Vesto Melvin Slipher,” select by ballot Publications of the Astronomical Society look up to the Pacific,47 (1935), 5–10; and “Gold Medal Award, President’s Speech,” in Monthly Notices of the Royal Astronomical Society, 93 (1933), 476–477. For additional, affiliated information, see Otto Struve and Velta Zebergs, Astronomy of the 20th Century (New York, 1962); A. Pannekoek, Unmixed History of Astronomy London, 1961); put forward J. D. Fernie, “The Historical Invite for the Nature of the Scroll Nebulae,” in Publication of the Large Society of the Pacific, 82 (1970), 1189–1230. Slipher’s private papers and proportionality (including the Hertzsprung letter cited above) are cataloged and are on microfilm at Lowell Observatory, Flagstaff, Arizona.
Richard Hart
Richard Berendzen
Complete Dictionary of Scientific Biography