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 Universi ...
in 1909.
He spent his entire career at
Lowell Observatory in
Flagstaff, Arizona, 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.
His brother
Earl C. Slipher was also an astronomer and a director at the
Lowell Observatory.
Slipher used
spectroscopy to investigate the rotation periods of
planets and the composition of planetary atmospheres. In 1912, he was the first to observe the shift of spectral lines of
galaxies, 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
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 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 exp ...
. Later, Slipher's and additional spectroscopic measurements of radial velocities were combined by
Edwin Hubble 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
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 exp ...
.
Slipher died in
Flagstaff, Arizona 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, a ...
(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 180 ...
(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 ...
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 fi ...
(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 of ...
is named after Earl and Vesto Slipher, as is the crater
Slipher on Mars and the
asteroid 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. SlipherThe 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 scanned ...
{{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