Sunday, November 11, 2012

Vesto Slipher

Vesto Melvin Slipher was born on November 11, 1875 at a farm in Mulberry, Indiana. His younger brother Earl was also an astronomer. He graduated from high school in Frankfort, Indiana and taught briefly at a country school before going to the University of Indiana in Bloomington, Indiana starting in 1897. He earned his bachelors degree in astronomy and mechanics in 1901. He earned his masters in 1903 and his doctorate in 1909 with a dissertation on the spectrum of Mars. One of his professors, Wilbur Cogshall, recommended him to Percival Lowell and Lowell brought Slipher on as an assistant in 1901. Slipher remained at the observatory for fifty three years afterward. He became assistant director in 1915 and became acting director in 1916 with Lowell's death. He became director in 1926 and served there until his retirement in 1954.

Slipher's first project, at the direction of Lowell, writing from his Boston office, was mounting and using the new spectrograph on Lowell's 24-inch refracting telescope. Slipher used it to record the spectra of Mars, Jupiter, and Saturn. Using the spectra that Slipher produced the confirmed the visually known periods of the planets. Using spectra taken of Mars, he attempted to prove there was water in the Martian atmosphere and he attempted to find the rotational period of Venus. He then turned the telescope to the gas giants and determined that the rotational period of Uranus was 10.75 hrs (it was later determined to be 25 hrs.).

Slipher is remembered chiefly for the work that he did determining the velocity of what at the time where called spiral nebula. Today we know these spiral shaped clouds are galaxies, just like our Milky Way. Slipher determined that these spiral nebula were moving much faster (three times) the velocity of any object observed at that time. Edwin Hubble later used this data to show the universe was expanding and the farther an object was away from Earth, the faster it would be moving away. Slipher is also responsible for hiring Clyde Tombaugh and was responsible for overseeing the work involved in the discovery of Pluto.

Awards won by Slipher include the Bruce Medal (1935), the Lalande Prize (1919), a Gold Medal from the Royal Society (1932), the Henry Draper Prize from the National Academy of Sciences (1932) and a gold medal from the Paris Academy of Sciences (1919). Slipher also has a crater on the moon named after him. In addition to his scientific work Slipher was also active in the community of Flagstaff, Arizona, where he was one of the founders of  its first high school.

Slipher died on November 8, 1969, in Flagstaff, Arizona.


Hoyt, Willliam Graves, "Vesto Melvin Slipher: 1875-1969"; National Academy Press, 1980

Trimble, Virginia; Williams, Thomas; Bracher, Katherine; Jarrell, Richard; Marche, Jordan; and Ragep, F. Jamil; "Vesto Slipher" in Biographical Encyclopedia of Astronomers; Springer; 2006

Vesto Sipher Wikipedia Entry

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