Vesto Melvin Slipher (; November 11, 1875 – November 8, 1969) was an American astronomer who performed the first measurements of radial velocities for galaxies. He was the first to discover that distant galaxies are redshifted, thus providing the first empirical basis for the expansion of the universe. He was also the first to relate these redshifts to velocity.

Biography

Slipher was born in Mulberry, Indiana, and completed his doctorate at Indiana University in 1909. He spent his entire career at

Lowell Observatory Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark ...

Flagstaff, Arizona Flagstaff ( ) is a city in, and the county seat of, Coconino County, Arizona, Coconino County in northern Arizona, in the southwestern United States. In 2019, the city's estimated population was 75,038. Flagstaff's combined metropolitan area has ...

, where he was promoted to assistant director in 1915, acting director in 1916, and finally director from 1926 until his retirement in 1952. His great grandfather helped established a Lutheran church. Delegates to the Fourth Conference International Union for Cooperation in Solar Research at Mount Wilson Observatory

Delegates to the Fourth Conference International Union for Cooperation in Solar Research at Mount Wilson Observatory

His brother

Earl C. Slipher Earl Carl Slipher (; March 25, 1883 – August 7, 1964) was an American astronomer, and politician. He was the brother of astronomer Vesto Slipher. He served in both the Arizona House of Representatives and the Arizona State Senate. Biography Sl ...

was also an astronomer and a director at the

. Slipher used

spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wa ...

to investigate the rotation periods of

planets A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young ...

and the composition of planetary atmospheres. In 1912, he was the first to observe the shift of spectral lines of

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

, making him the discoverer of galactic redshifts. In 1914, Slipher also made the first discovery of the rotation of spiral galaxies. He discovered the sodium layer in 1929. He was responsible for hiring Clyde Tombaugh and supervised the work that led to the discovery of Pluto in 1930. By 1917, Slipher had measured the radial velocities of 25 "spiral nebulae," and found that all but three of those galaxies were moving away from us, at substantial speeds. Slipher himself speculated that this might be due to the motion of our own galaxy – as in his sample, those galaxies moving towards us and those moving away from us were roughly in opposite directions. In hindsight, this was the first data supporting models of an expanding universe. Later, Slipher's and additional spectroscopic measurements of radial velocities were combined by

Edwin Hubble Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an Americans, American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. Hubble proved that many objects ...

with Hubble's own determinations of galaxy distances, leading Hubble to discover the (at that time, rough) proportionality between galaxies' distances and redshifts, which is today termed Hubble–Lemaître's law (formerly named as Hubble's law, the IAU Decision of October 2018 recommends the use of a new name), was formulated by Hubble and Humason in 1929 and became the basis for the modern model of the expanding universe. Slipher died in

and is buried there in Citizens Cemetery.

Awards

* Member of the American Academy of Arts and Sciences (elected 1909) * Lalande Prize (1919) * Gold Medal of the Paris Academy of Sciences (1919) * Henry Draper Medal of the National Academy of Sciences (1932) * Gold Medal of the Royal Astronomical Society (1932) * Bruce Medal (1935) * The crater Slipher on the Moon is named after Earl and Vesto Slipher, as is the crater Slipher on Mars and the

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

1766 Slipher 1766 Slipher, provisional designation , is a Paduan asteroid from the central regions of the asteroid belt, approximately 18 kilometers in diameter. It was discovered on 7 September 1962, by astronomers of the Indiana Asteroid Program at Goethe Li ...

, discovered September 7, 1962, by the Indiana Asteroid Program.

Notes

External links

Library of Lowell Observatory: Biography of V. M. Slipher

The Royal Observatory, Edinburgh: History, Papers & External Links on V. M. Slipher
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V. Slipher
@ Astrophysics Data System {{DEFAULTSORT:Slipher, Vesto 1875 births 1969 deaths 20th-century American astronomers Indiana University alumni People from Clinton County, Indiana Recipients of the Gold Medal of the Royal Astronomical Society People from Flagstaff, Arizona Recipients of the Lalande Prize Members of the United States National Academy of Sciences Fellows of the American Academy of Arts and Sciences