Born Lisbon, New Hampshire, USA, 29 December 1854
Died Norwell, Massachusetts, USA, 5 June 1931
Solon Bailey, a prominent American astronomer in the late nineteenth and early twentieth centuries, was known primarily for his discovery and study of variable stars in globular clusters, now known as RR Lyrae stars, and for his extensive long-exposure photographic surveys of southern skies and photometric catalog of southern stars.
After receiving an M.A. from Boston University, in 1884, and teaching at Tilton Academy for a short period, Bailey entered graduate studies at the Harvard College Observatory, where he earned a second M.A. in 1888.
In 1889, Edward Pickering , the Harvard College Observatory director, sent Bailey to survey the Andes Mountains for possible sites for a southern extension of the Harvard College Observatory. After several arduous years of travel up and down the Andes chain, Bailey recommended a site near Arequipa, Peru, as the best of several possible sites for an astronomical observatory. Pickering accepted that recommendation, and sent his brother, William Pickering , along with Andrew Douglass and a small staff of other Harvard personnel, to Arequipa. W. H. Pickering directed the construction of the observatory and establishment of the observing program. However, after several years of poor communication between Cambridge and Arequipa, during which W. H. Pickering spent much more of the available money than anticipated for construction, and failed to establish the type of stellar observing program desired, in 1893 E. C. Pickering recalled his brother to Cambridge, and asked Bailey to again take charge of Harvard’s southern station. Bailey and his family returned to Arequipa, where they remained until he was replaced by Frank Hinkley in 1909. The Baileys returned to Peru a total of five times.
One of Bailey’s primary accomplishments after returning to Arequipa was the extension of the Harvard Photometry to the South Celestial Pole. Using a meridian photometer brought from Cambridge, Bailey cataloged the brightness of 7,922 stars not visible from Massachusetts. This southern extension to provide full sky coverage contributed substantially to the later acceptance of the Harvard system as an international standard.
Among the other projects Bailey initiated as part of the observing program of the Arequipa station was photography of nebulae and globular clusters. That project included taking objective prism plates for the Henry Draper Memorial project with the Bruce 24-in. doublet photographic telescope. Bailey’s assistants carefully examined the plates they took to ensure adequate quality of the recorded spectra, and were thus the first to have the opportunity for discoveries of new objects photographed on each plate. After resolving a minor dispute over roles and priorities with Williamina Fleming , Harvard’s first famous woman astronomer, Bailey and his assistants discovered a number of new variable stars based on the presence of certain characteristic hydrogen emission lines in the stellar spectra. Between 1895 and 1898 he and his assistants found over 500 globular cluster variables, most of which were to be later to be classified as the RR Lyrae stars. Bailey’s determinations of the periods of these variables, all within the range of 0.5–1.5 days, proved extremely accurate. The long exposure plates collected during this survey constituted a rich resource for later studies of clusters, galaxies, and nebulae in the southern skies.
The short focal length of the Bruce telescope limited its ability to resolve stars in the crowded regions of globular clusters. Bailey realized that a large telescope and very sensitive plates were critical for his work. At that time there was only one observatory in the world with the necessary equipment – the Lick Observatory in California. E. C. Pickering requested that Lick make plates of M3 with the 36-in. Crossley reflector. The Lick plates would be an important part of Bailey’s 1913 presentations of the variable stars in Messier 3. Bailey’s studies of variable stars in clusters were extended to M5, M15, and Omega Centauri.
From his site survey work, Bailey recognized the value of regular meteorological observations, and established a series of meteorological stations along the Andes. The stations included what was then the highest meteorological station in the world atop a nearby Andean volcano, 19,000-ft “El Misti.” Other meteorological stations were placed along the coast at sea level as well as on various peaks and high plateaus in the Andes. Over the next 41 years (from 1889 to 1930) Bailey published regular Peruvian Meteorology reports for this South American network.
After returning from Peru, Bailey was active in the astronomical community in the Boston area. In 1912, after the retirement of professor Arthur Searle, Bailey was appointed Phillips Professor of Astronomy. In 1918, he served as one of the incorporators of the American Association of Variable Star Observers [AAVSO]. After Edward Pickering’s death in 1919, Bailey became acting director of the Harvard College Observatory. However, it was the young Harlow Shapley who would eventually become director of the observatory, and not Bailey. Perhaps it was Bailey’s age (64), and Shapley’s youthful exuberance, which prevailed in that decision. To a great degree, Shapley’s success in the area of globular clusters and variables was due to his collaboration and communications with Bailey.
Solon Bailey’s legacy remains his observations, which are considered a foundation for those of the likes of Shapley who would follow him. He was elected president of the International Astronomical Union’s Commission on Variable Stars in 1922. He was elected a member of the National Academy of Sciences in 1923. The University of San Augustine, Peru, conferred an honorary Ph.D. degree on Bailey in that same year.
Bailey’s wife, Ruth Poulter Bailey, and young son Irving Widmer accompanied him on many trips to Peru. Irving spent most of his boyhood in Peru, accompanying his father on trips in the Andes, trips which ranged from jungle to barren mountain slopes. Bailey and his family also were to endure the death throes of the Peruvian Aristocratic Republic’s “Revolution of 1895.” This revolution culminated in the Aristocratic Republic, during which Peru experienced relative political harmony and rapid economic growth as well as social and political change.