Vesto Melvin Slipher (; November 11, 1875 – November 8, 1969) was an American

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

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 Indiana University (IU) is a system of public universities in the U.S. state of Indiana. Campuses Indiana University has two core campuses, five regional campuses, and two regional centers under the administration of IUPUI. *Indiana Universit ...

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 in northern Arizona, in the southwestern United States. In 2019, the city's estimated population was 75,038. Flagstaff's combined metropolitan area has an estimated population ...

, 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 S ...

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 yo ...

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 physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase ...

. 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 Clyde William Tombaugh (February 4, 1906 January 17, 1997) was an American astronomer. He discovered Pluto in 1930, the first object to be discovered in what would later be identified as the Kuiper belt. At the time of discovery, Pluto was cons ...

and supervised the work that led to the discovery of

Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest k ...

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 The expansion of the universe is the increase in distance between any two given gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion whereby the scale of space itself changes. The universe does not ex ...

. 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 American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. Hubble proved that many objects previousl ...

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

. Slipher died in

and is buried there in Citizens Cemetery.

Awards

* Member of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, ...

(elected 1909) *

Lalande Prize The Lalande Prize (French: ''Prix Lalande'' also known as Lalande Medal) was an award for scientific advances in astronomy, given from 1802 until 1970 by the French Academy of Sciences. The prize was endowed by astronomer Jérôme Lalande in 1801 ...

(1919) * Gold Medal of the Paris Academy of Sciences (1919) *

Henry Draper Medal The Henry Draper Medal is awarded every 4 years by the United States National Academy of Sciences "for investigations in astronomical physics". Named after Henry Draper, the medal is awarded with a gift of USD $15,000. The medal was established u ...

of the National Academy of Sciences (1932) *

Gold Medal of the Royal Astronomical Society The Gold Medal of the Royal Astronomical Society is the highest award given by the Royal Astronomical Society (RAS). The RAS Council have "complete freedom as to the grounds on which it is awarded" and it can be awarded for any reason. Past awar ...

(1932) *

Bruce Medal The Catherine Wolfe Bruce Gold Medal is awarded every year by the Astronomical Society of the Pacific for outstanding lifetime contributions to astronomy. It is named after Catherine Wolfe Bruce, an American patroness of astronomy, and was f ...

(1935) * The crater Slipher on the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width ...

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, 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
*
V. Slipher
@

Astrophysics Data System The SAO/NASA Astrophysics Data System (ADS) is an online database of over 16 million astronomy and physics papers from both peer reviewed and non-peer reviewed sources. Abstracts are available free online for almost all articles, and full scanne ...

{{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