Highlights from 125 Years of Lowell Observatory Science: Vera Rubin and the Identification of Dark Matter

Vera Rubin's identification of dark matter in the Andromeda galaxy using Lowell Observatory's Perkins 72-inch and the KPNO 84-inch telescopes with Kent Ford's image-tube spectrograph represented the culmination and intersection of scientific, technological, collaborative, and managerial interests that spanned the continental United States in the late 1950s and 1960s. Highly sensitive spectroscopic observations were required to detect the redshifts of M31's HII regions, particularly in the outer more tenuous reaches of the great spiral, and adequately generous allocations of telescope time were needed to map out these motions across the whole spatial extent of Andromeda. Because of the constructive spirit of cooperation between scientific and technical staff at Lowell Observatory, Carnegie DTM, Ohio State, USNO, KPNO, Carnegie Pasadena, and other institutions and players, in 1967, driven by an interest in galactic dynamics and the availability of the image-tube spectrograph, Rubin and Ford began a three-year project, dismissed by some colleagues as not worth doing and as overly time-consuming, which ultimately revealed evidence for Fritz Zwicky's conjecture that a significant fraction of gravitationally active matter is not luminous. Rubin pioneered work on some of the most fundamental problems in astrophysics and was an inspiration and supporter to scientists, faculty, and staff at universities and observatories around the world. She made rich contributions to the science and culture at Lowell Observatory where she served on the Board of Advisors for many years and was a colleague and role model to many.