:Vesto Slipher

Vesto Melvin Slipher was born in Mulberry, Indiana, to Daniel Clark and Hannah App Slipher. He spent his early years working on his family farm in Mulberry.{{Cite journal |last=Graves Hoyt |first=William |date=1980 |editor-last=Crawford Jr. |editor-first=Bryce |editor2-last=McEuen |editor2-first=Caroline K. |title=Vesto Melvin Slipher |journal=Biographical Memoirs of the National Academy of Sciences |publisher=National Academy Press |volume=52 |page=413}} Vesto had a younger brother, Earl C. Slipher, who was also an astronomer at Lowell Observatory.

Slipher went to high school in Frankfort, IN. He then attended Indiana University in Bloomington, IN and earned his Bachelor's Degree in Mechanics and Astronomy in June 1901.{{Cite journal |last=Graves Hoyt |first=William |date=1980 |editor-last=Crawford Jr. |editor-first=Bryce |editor2-last=McEuen |editor2-first=Caroline K. |title=Vesto Melvin Slipher |journal=Biographical Memoirs of the National Academy of Sciences |publisher=National Academy Press |volume=52 |page=414}} Two years later, Slipher earned his Master's Degree in the same program. At the age of 33, Vesto graduated with his Ph.D. in Mechanics and Astronomy from Indiana University.

While at school at Indiana University, Slipher formed a personal bond with one of his professors, William Cogshall. Cogshall was one of the main reasons Slipher became interested in astronomy in the first place. Cogshall convinced Percival Lowell, director of the Lowell Observatory in Flagstaff, Arizona, to take Vesto in as a temporary assistant.{{Cite journal |last=Graves Hoyt |first=William |year=1980 |editor-last=Crawford Jr. |editor-first=Bryce |editor2-last=McEuen |editor2-first=Carolina K. |title=Vesto Melvin Slipher |journal=Biographical Memoirs of the National Academy of Sciences |publisher=National Academy Press |volume=52 |page=414}} Slipher worked as an assistant from 1901 to 1915 when Lowell finally named him the assistant director of the observatory. One year later Percival Lowell died and Vesto became the acting director for the next ten years. In 1926, 25 years after arriving in Flagstaff, Slipher was named director of the Lowell Observatory. He remained in charge for 28 more years when he retired from professional life.{{Cite journal |last=Graves Hoyt |first=William |year=1980 |editor-last=Crawford Jr. |editor-first=Bryce |editor2-last=McEuen |editor2-first=Caroline K. |title=Vesto Melvin Slipher |journal=Biographical Memoirs of the National Academy of Sciences |publisher=National Academy Press |volume=52 |pages=414–415}} Slipher spent his years there studying many things, but most notably, spectroscopy and redshifts of spiral nebulae.

The first major task Slipher was given was to measure the Solar System's planets' rotation interval.{{Cite book |last=Moore |first=Patrick |title=Men of the Stars |publisher=Gallery Books |year=1986 |isbn=0831758155 |page=84}} He was one of the first astronomers to show that Uranus has a much faster rotation than Earth, similar to the other giant planets in the Solar System. What Vesto is most known for though is his work with spiral nebulae, or, spiral galaxies, like the Milky Way and Andromeda. His initial goal was to measure how fast the nebulae were moving. His discoveries were confirmed ten years later when Edwin Hubble used the Mount Wilson Observatory reflector to view the galaxies much more clearly.

File:Delegates to the Fourth Conference International Union for Cooperation in Solar Research at Mount Wilson Observatory.jpg in California]]

Slipher introduced as early as 1909 that the infrared spectrum could be recorded using photographic emulsions, and used those to record the absorption lines of sunlight and major planets.{{Cite book |url=https://www.worldcat.org/oclc/900836268 |title=A Source Book in Astronomy and Astrophysics, 1900–1975 |date=1979 |publisher=Harvard University Press |others=Owen Gingerich, Kenneth R. Lang |isbn=978-0-674-36667-1 |location=[Erscheinungsort nicht ermittelbar] |pages=67 |oclc=900836268}} He found that the planets showed different absorption lines that were not present in sunlight, and identified those bands with ammonia and methane. In the early twentieth century, Vesto Slipher elongated the spectrum to include the red and infrared wavelengths and showed that the major planets display strong absorption lines at many different wavelengths.{{Cite book |url=https://www.worldcat.org/oclc/900836268 |title=A Source Book in Astronomy and Astrophysics, 1900–1975 |date=1979 |publisher=Harvard University Press |others=Owen Gingerich, Kenneth R. Lang |isbn=978-0-674-36667-1 |location=[Erscheinungsort nicht ermittelbar] |page=117 |oclc=900836268}} 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.Slipher first reports on the making the first Doppler measurement on September 17, 1912 in [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1913LowOB...1b..56S&db_key=AST&data_type=HTML&format=&high=448f04e38822894 The radial velocity of the Andromeda Nebula] in the inaugural volume of the Lowell Observatory Bulletin, pp. 2.56–2.57. In his report Slipher writes: "The magnitude of this velocity, which is the greatest hitherto observed, raises the question whether the velocity-like displacement might not be due to some other cause, but I believe we have at present no other interpretation for it." Three years later, Slipher wrote a review in the journal Popular Astronomy, Vol. 23, pp. 21–24 [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1915PA.....23...21S&db_key=AST&data_type=HTML&format=&high=448f04e38822894 Spectrographic Observations of Nebulae], in which he states, "The early discovery that the great Andromeda spiral had the quite exceptional velocity of -300 km(/s) showed the means then available, capable of investigating not only the spectra of the spirals but their velocities as well." Slipher reported the velocities for 15 spiral nebula spread across the entire celestial sphere, all but three having observable "positive" (that is recessional) velocities. Using the Doppler effect and noting subtle changes, he measured the speeds in which spiral nebulae traveled during his research from 1912 and onward.{{Cite book |last=Helicon |url=https://www.worldcat.org/oclc/923353697 |title=Hutchinson Trends in Science : Astronomy. |date=2006 |publisher=Helicon Publishing |isbn=978-1-85986-504-0 |location=Abingdon |pages=15, 19|oclc=923353697}}

These subtle changes in the speeds of the nebulae led Slipher to conclude that the nebulae were not within the Milky Way galaxy.{{Cite book |last=Publishing |first=Helicon |title=Hutchinson Trends in Science – Astronomy|publisher=Helicon Publishing |year=2006 |isbn=978-1859865040 |pages=15, 19}} In 1914, Slipher also made the first discovery of the rotation of spiral galaxies.{{Cite news |last= Slipher |first= Vesto |date=1914 |title= The detection of nebular rotation |journal= Lowell Observatory Bulletin, 62}}

He discovered the sodium layer in 1929.{{Cite web | url=http://www.albany.edu/faculty/rgk/atm101/sodium.htm | title=The Metallic Vapor Layers}} 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.{{cite journal|author=Slipher, Vesto|journal=Proceedings of the American Philosophical Society|volume=56|pages=403–409|year=1917|bibcode=1917PAPhS..56..403S|title=Nebulae}}

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 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 the Hubble–Lemaître law (formerly named Hubble's law; the IAU Decision of October 2018 recommends the use of a new name{{Cite web|url=https://www.iau.org/news/pressreleases/detail/iau1812/|title=International Astronomical Union {{!}} IAU|website=www.iau.org|access-date=2019-08-26}}), was formulated by Hubble and Humason in 1929 and became the basis for the modern model of the expanding universe.

Slipher married Emma R. Munger in 1904 in Frankfort, IN. Vesto and Emma had two children together, David Clark and Marcia Frances.{{Cite journal |last=Graves Hoyt |first=William |date=1980 |editor-last=Crawford Jr. |editor-first=Bryce |editor2-last=McEuen |editor2-first=Caroline K. |title=Vesto Melvin Slipher |journal=Biographical Memoirs of the National Academy of Sciences |publisher=National Academy Press |volume=52 |page=415}}

In 1901, Vesto Slipher moved to Flagstaff, Arizona and began work at Lowell Observatory. He spent the next 53 years of his life working at Lowell Observatory as an assistant and then the director of the observatory until his retirement in 1954. Slipher lived until age 93 and died in Flagstaff in 1969. He is buried at Citizens Cemetery in Flagstaff.{{Cite book |last=Nickell |first=Duane S. |title=Scientific Indiana |publisher=The History Press |year=2021 |isbn=9781467149488 |page=37}}{{cite web |title=Vesto Melvin Slipher |url=https://arizonagravestones.org/view.php?id=92752 |website=arizonagravestones.org |publisher=Gravestone Photo Project (GPP)}}

• Member of the American Academy of Arts and Sciences (elected 1909){{cite web |title=Member Directory |url=https://www.amacad.org/person/vesto-melvin-slipher |website=American Academy of Arts and Sciences |access-date=October 7, 2022}}
• Lalande Prize (1919)
• Gold Medal of the Paris Academy of Sciences (1919)
• Member of the United States National Academy of Sciences (1921){{Cite web |title=Vesto M. Slipher |url=http://www.nasonline.org/member-directory/deceased-members/20001710.html |access-date=2023-09-13 |website=www.nasonline.org}}
• Member of the American Philosophical Society (1921){{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Vesto+M.+Slipher&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=2023-09-13 |website=search.amphilsoc.org}}
• Henry Draper Medal of the National Academy of Sciences (1932){{cite web|title=Henry Draper Medal |url=http://www.nasonline.org/about-nas/awards/henry-draper-medal.html |publisher=National Academy of Sciences |access-date=24 February 2011 |url-status=dead |archive-url=https://web.archive.org/web/20130126003930/http://www.nasonline.org/about-nas/awards/henry-draper-medal.html |archive-date=January 26, 2013 }}
• Gold Medal of the Royal Astronomical Society (1932){{cite web|title=Winners of the Gold Medal of the Royal Astronomical Society|url=http://www.ras.org.uk/awards-and-grants/awards/268|publisher=Royal Astronomical Society|access-date=24 February 2011|url-status=dead|archive-url=https://web.archive.org/web/20110525064844/http://www.ras.org.uk/awards-and-grants/awards/268|archive-date=25 May 2011}}
• Bruce Medal (1935){{cite web|title=Past Winners of the Catherine Wolfe Bruce Gold Medal|url=http://astrosociety.org/membership/awards/pastbruce.html|publisher=Astronomical Society of the Pacific|access-date=24 February 2011}}
• The crater Slipher on the Moon is named after Earl and Vesto Slipher, as is the crater Slipher on Mars and the asteroid 1766 Slipher, discovered September 7, 1962, by the Indiana Asteroid Program.

{{Reflist}}

• {{Cite book|last=Hoyt|first=William Graves|chapter=Vesto Melvin Slipher|year=1980|editor-last=Crawford Jr.|editor-first=Bryce|editor2-last=McEuen|editor2-first=Caroline K.|title=Biographical Memoirs of the National Academy of Sciences |publisher=National Academies Press|place=Washington D.C.|volume=52|pages=411–449|via=Internet Archive|url=https://archive.org/details/biographicalmemo0052nati_u3j0/page/n3/mode/2up|isbn=0-309-03099-4}}

• [https://web.archive.org/web/20070927002645/http://www.lowell.edu/Research/library/paper/vm_slipher.html Library of Lowell Observatory: Biography of V. M. Slipher]
• [http://www.roe.ac.uk/~jap/slipher/ The Royal Observatory, Edinburgh: History, Papers & External Links on V. M. Slipher]
• {{Find a Grave|7129315|Vesto Melvin Slipher}}
• [http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&author=slipher,%20v.&aut_syn=NO V. Slipher] @ Astrophysics Data System

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Category:1875 births

Category:1969 deaths

Category:20th-century American astronomers

Category:Indiana University alumni

Category:People from Clinton County, Indiana

Category:Recipients of the Gold Medal of the Royal Astronomical Society

Category:People from Flagstaff, Arizona

Category:Recipients of the Lalande Prize

Category:Members of the United States National Academy of Sciences

Category:Fellows of the American Academy of Arts and Sciences

Category:Members of the American Philosophical Society