Frank Elmore Ross is a prominent American astronomer, mathematician, and physicist. He is known for the Ross correcting lens and his lists of new proper-motion stars. He photographed Mars and Venus from Mount Wilson, discovering markings in Venus's clouds in the ultraviolet.
Background
Frank Elmore Ross was born on April 2, 1874, in San Francisco, California, the son of Daniel Walter and Katherine (Harris) Ross. His father, a building contractor, lost a fortune during the California gold-mining boom. In 1882, the family moved to San Rafael, California.
Education
Ross obtained a Bachelor of Science degree from the University of California at Berkeley in 1896 and received a Ph.D. degree from the same University in 1901.
When Ross obtained a Bachelor of Science degree from the University of California at Berkeley in 1896, for several years thereafter he gained valuable experience through one-year appointments as teacher (mathematics and physics at Mt. Tamalpais Military Academy), on fellowships (a year each at Berkeley and Lick Observatory), and as an assistant professor of mathematics at the University of Nevada.
After receiving his doctorate in 1901, for the next two years, Ross computed perturbations of Watson asteroids, then spent a year as an assistant in the Nautical Almanac Office, where he attracted the attention of Simon Newcomb.
For two years Ross was a research assistant at the Carnegie Institution, working on planetary and lunar problems under Newcomb. At Newcomb’s suggestion, he computed a definitive orbit of Phoebe, the ninth satellite of Saturn. This was his first major independent publication in astronomy. The differential coordinates of Phoebe given in the American Ephemeris beginning with 1909 are derived from the elements and tables published by Ross.
In 1905 Ross became director of the International Latitude Observatory at Gaithersburg, Maryland, where he took part in the observations and reductions for the precise determination of latitude required to study the motion of the earth’s axis of rotation. In 1909 the U.S. Coast and Geodetic Survey received a grant from the International Geodetic Association for the construction and operation of a photographic instrument to be used in determining the latitude variation. The instrument, known as the photographic zenith tube, or PZT, was designed by Ross.
The optical system of the PZT is patterned after the visual instrument known as the zenith tube, which had been designed by Airy and installed at Greenwich in 1851. Airy’s instrument was no longer in use, but Ross recognized the merits of its basic principle and was successful in developing an improved telescope of extremely high precision. He modified the optical system by locating the second nodal point of the lens in the focal plane, and he constructed it to operate as a photographic instrument. The PZT then had two major improvements over Airy’s instrument: the first made the PZT insensitive to tilt of the lens; the second was effective in smoothing out short-period oscillations caused by refraction and also made the instrument impersonal.
The completed instrument was installed at Gaithersburg in June 1911, and by October 1914 Ross had photographed 6,944 stars on a total of 450 nights. Thereafter the program was discontinued by the Coast and Geodetic Survey and the instrument was sold to the U.S. Naval Observatory, where it was designated as PZT no. 1 and was in continuous operation from 1915 until 1955. In 1934 the instrument was modified to determine time as well as the variation in latitude. Its use for the determination of time proved to be superior to visual methods, and copies of the instrument are used by the world's major time services.
While at Gaithersburg, Ross completed the computations of the orbits of the sixth and seventh satellites of Jupiter that he had begun in Washington. His elements and tables were used to derive the differential coordinates of these satellites, which were published in the American Ephemeris from 1912 through 1947.
In 1912 Ross turned his attention to the cause of the discordance between the positions of Mars deduced from observations and those computed from Newcomb’s theory of Mars in Astronomical Papers; this discordance amounted to six seconds of arc in right ascension in 1905. Ross’s corrections to Newcomb's theory, published in Astronomical Papers (1917), have been used in the American Ephemeris, beginning with the volumes for 1922.
Ross is listed in the American Ephemeris as a part-time member of the staff of the Nautical Almanac Office from 1907 to 1919. In 1915 he was appointed physicist at the Eastman Kodak Company laboratories, where for nine years he studied and perfected the techniques of photography and lens design that he later successfully applied in astronomy. In 1924 he joined the staff of the Yerkes Observatory, where he continued astronomical observations until his retirement in 1939. While at Yerkes he was on the faculty of the University of Chicago as associate professor (1924-1928) and professor (1929-1939) of astronomy.
One of Ross’s early projects at Yerkes was to rephotograph the stellar fields that had been photographed by Barnard. In comparing the new plates with the older ones, he found many variable stars and stars with large proper motions. The Astronomical Journal reported these discoveries, and by 1931 Ross was credited with the discovery of 379 variable stars and 869 proper-motion stars.
Ross photographed Mars in different colors with the Mount Wilson sixty-inch reflector and with the Lick thirty-six-inch refractor at the planet’s opposition in 1926. The next year his photographic observations of Venus at Mount Wilson Observatory revealed unusual temporary markings, or shadings, in the planet's atmosphere.
Ross spent the remainder of his life in California after his retirement from the Yerkes Observatory in 1939. He was furnished an office at the Mount Wilson Observatory, although he was not an official member of the staff.
In his religious affiliation, Ross was a Presbyterian.
Politics
Ross was a member of the Republican political party.
Membership
Ross was a member of the American Astronomical Society, the National Academy of Sciences (1930), and was an associate member of the Royal Astronomical Society.
Royal Astronomical Society
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United Kingdom
Connections
Ross was married three times. His first wife's name was Married Margaret J. Benton, whom he married on May 5, 1904. He was married a second time on June 10, 1913, to Elizabeth Bischoff. His third wife's name was Anna Lee, whom he married on August 21, 1939. Ross had two children: Alan K. Ross and Barbara H. Ross.