View source for Gerard Kuiper

{{Short description|Dutch astronomer (1905–1973)}}
{{Distinguish|text=the mathematician [[Nicolaas Kuiper]]}}
{{Use dmy dates|date=September 2022}}
{{Infobox scientist
| honorific_prefix   = 
| name               = Gerard Kuiper
| honorific_suffix   = 
| image              = Gerard Kuiper 1964b.jpg
| alt                = 
| caption            = Kuiper in 1964
| birth_name         = Gerrit Pieter Kuiper
| birth_date         = {{Birth date|1905|12|7|df=y}}
| birth_place        = [[Tuitjenhorn]], Netherlands
| death_date         = {{Death date and age|1973|12|23|1905|12|7|df=y}}
| death_place        = [[Mexico City]], Mexico
| nationality        = Dutch
| other_names        = 
| alma_mater         = [[Leiden University]]
| occupation         = {{hlist|[[Astronomer]]|[[Planetary science|planetary scientist]]|[[selenographer]]|author|professor}}
| era                = 
| employer           = 
| known_for          = [[Kuiper belt]]
| notable_works      = 
| spouse             = {{marriage|Sarah Fuller|1936}}
| field = [[Astronomy]]
| thesis_title       = Statistische onderzoekingen van dubbelsterren
| thesis_url         = http://www.worldcat.org/oclc/1120104305
| thesis_year        = 1933
| doctoral_advisor   =
| doctoral_students  = [[Carl Sagan]]
| awards             = 
}}

'''Gerard Peter Kuiper''' ({{IPAc-en|ˈ|k|aɪ|p|ər}} {{respell|KY|pər}}; born '''Gerrit Pieter Kuiper''', {{IPA|nl|ˈɣɛrɪt ˈpitər ˈkœypər|lang}}; 7&nbsp;December 1905 – 23&nbsp;December 1973) was a Dutch [[astronomer]], [[planetary scientist]], [[selenographer]], author and professor. The [[Kuiper belt]] is named after him.

Kuiper is considered by many to be the father of modern [[planetary science]].<ref>{{cite web |title=NASA Solar System Exploration |publisher=National Aeronautics and Space Administration (NASA) |website=solarsystem.nasa.gov |url=http://solarsystem.nasa.gov/people/profile.cfm?Code=KuiperG |access-date=12 April 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150411083843/http://solarsystem.nasa.gov/people/profile.cfm?Code=KuiperG |archive-date=11 April 2015}}</ref>

==Early life and education==
Kuiper, the son of a tailor in the village of [[Tuitjenhorn]] in [[North Holland]], had an early interest in astronomy. He had extraordinarily sharp eyesight, allowing him to see with the naked eye [[Apparent magnitude|magnitude]] 7.5&nbsp;stars, about four times fainter than those visible to normal eyes.<ref name=":0" />

He studied at [[Leiden University]] in 1924, where at the time a very large number of astronomers had congregated. He befriended fellow students [[Bart Bok]] and [[Pieter Oosterhoff]], and was taught by [[Ejnar Hertzsprung]], [[Antonie Pannekoek]], [[Willem de Sitter]], [[Jan Woltjer (astronomer)|Jan Woltjer]], [[Jan Oort]], and the physicist [[Paul Ehrenfest]]. He received his [[Candidate (degree)|candidate degree]] in Astronomy in 1927 and continued straight on with his graduate studies.

Kuiper received his PhD degree from Leiden University in the Netherlands on his thesis on [[binary star]]s with Hertzsprung in 1933.

==Career==
He traveled to California to become a fellow under [[Robert Grant Aitken]] at the [[Lick Observatory]]. In 1935 he left to work at the [[Harvard College Observatory]], where he met Sarah Parker Fuller (1913-2000), whom he married on 20&nbsp;June 1936. Although he had planned to move to [[Java]] to work at the [[Bosscha Observatory]], he took a position at [[Yerkes Observatory]] of the [[University of Chicago]] and received American citizenship in 1937.

From 1947 to 1949, Kuiper served as the director of the [[Yerkes Observatory]], as well as the [[McDonald Observatory]] in west Texas.<ref name=":0">{{Cite journal |last=Cruikshank |first=Dale P. |date=1993 |title=Gerard Peter Kuiper, December 7, 1905–December 24, 1973 |url=https://www.nasonline.org/wp-content/uploads/2024/06/kuiper-gerard.pdf |journal=[[Biographical Memoirs of the National Academy of Sciences]] |issue=62 |pages=258–295}}</ref> In 1949, Kuiper initiated the Yerkes–McDonald asteroid survey (1950–1952).

From 1950-1960 he was professor at the [[University of Chicago]], and from 1957 to 1959, Kuiper once again served as the director of the [[Yerkes Observatory|Yerkes]] and [[McDonald Observatory|McDonald Observatories]].<ref name=":0" />

[[File:Heacock, Kuiper, and Whitaker.jpg|thumb|Experimenters [[Raymond Heacock]], Kuiper, and [[Ewen Whitaker]] examine [[Ranger 7]] pictures at the Flight Control Center]]

Kuiper was [[doctoral advisor]] to [[Carl Sagan]]. In 1958, the two worked on the classified military [[Project A119]], a secret Air Force plan to detonate a nuclear warhead on the moon.<ref name="Ulivi2004">{{cite book |last=Ulivi |first=Paolo |year=2004 |title=Lunar Exploration: Human pioneers and robotic surveyors |page=20 |publisher=[[Springer Science & Business Media]] |isbn=978-1-85233-746-9 |url=https://books.google.com/books?id=W1f4TvNUwLsC}}</ref> In 1959, he sent [[Jürgen Stock (astronomer)|Jürgen Stock]] to Chile, to search for suitable sites of an observatory for the Southern skies, who eventually would identify the spot for the [[Cerro Tololo Inter-American Observatory]].<ref name="silva">{{Cite journal |last=Silva |first=Bárbara |date=2022-06-21 |title=Un astrónomo, tres continentes, siete instituciones y millares de estrellas. La experiencia global de Jürgen Stock en los inicios de la astronomía en Chile |url=http://journals.openedition.org/nuevomundo/87629 |journal=Nuevo Mundo Mundos Nuevos |doi=10.4000/nuevomundo.87629 |issn=1626-0252|doi-access=free }}</ref>

In 1960 Kuiper moved to [[Tucson]], [[Arizona]], to found the [[Lunar and Planetary Laboratory]] at the [[University of Arizona]], serving as the laboratory's director for the rest of his life, until his death in 1973. 

===Discoveries===
[[File:Shoemaker and Kuiper.jpg|thumb|[[Eugene Shoemaker]] and Kuiper answer newsmen's questions at the Interim Scientific Results Conference of the [[Ranger program]].]]

Kuiper discovered two [[natural satellite]]s of [[planet]]s in the [[Solar System]], namely [[Uranus]]'s satellite [[Miranda (moon)|Miranda]] and [[Neptune]]'s satellite [[Nereid (moon)|Nereid]]. In addition, he discovered [[carbon dioxide]] in the atmosphere of [[Mars]], and the existence of a [[methane]]-laced [[Celestial body atmosphere|atmosphere]] above [[Saturn]]'s satellite [[Titan (moon)|Titan]] in 1944. Kuiper also pioneered airborne infrared observing using a [[Convair 990]] aircraft in the 1960s.

In the 1950s Kuiper's interdisciplinary collaboration with the geochemist and Nobel Laureate [[Harold C. Urey]] to understand the Moon's thermal evolution descended into acrimony, as the two engaged in what became known as the "Hot Moon, Cold Moon" controversy. Their falling out, in part a scientific dispute, also reflected the challenge of maintaining professional relationships across overlapping but distinct scientific disciplines.<ref>{{cite book |last=Doel |first=Ronald E. |year=1996 |title=Solar System Astronomy in America: Communities, patronage, and interdisciplinary science, 1920–1960 |publisher=Cambridge University Press |isbn=9780521115681 |location=New York}}</ref>

By 1950, Kuiper had contributed a theory for the ongoing problem of solar system origins. Kuiper claimed that gravitational instabilities would form in the solar nebula, which would then condense into protoplanets. However, Kuiper's theory failed to address the [[angular momentum problem]], simply attributing the loss of momentum to magnetic and electric fields instead of gravity.<ref name=":0" />

In 1951, in a paper in ''Astrophysics: A Topical Symposium'', Kuiper speculated that a large disc of small astronomical bodies formed early in the Solar System's evolution. He suggested that the disc consisted of "remnants of original clusterings which have lost many members that became stray asteroids, much as has occurred with open galactic clusters dissolving into stars."<ref name="Kuiper2">{{cite book |author1=Kuiper, G.P. |title=Astrophysics: A Topical Symposium |date=1951 |publisher=McGraw-Hill |editor1-last=Hynek |editor1-first=J.A. |location=New York City, New York, US |pages=357–424 |chapter=On the origin of the solar system}}</ref> In another paper, based upon a lecture Kuiper gave in 1950, also called ''On the Origin of the Solar System'', Kuiper wrote about the "outermost region of the solar nebula, from 38 to 50 astr. units (i.e., just outside proto-Neptune)" where "condensation products (ices of H<sub>2</sub>0, NH<sub>3</sub>, CH<sub>4</sub>, etc.) must have formed, and the flakes must have slowly collected and formed larger aggregates, estimated to range up to 1 km or more in size." He continued to write that "these condensations appear to account for the comets, in size, number and composition." According to Kuiper "the planet Pluto, which sweeps through the whole zone from 30 to 50 [[Astronomical unit|astr. units]], is held responsible for having started the scattering of the comets throughout the solar system."<ref>{{cite journal |last1=Kuiper |first1=Gerard |date=1951 |title=On the Origin of the Solar System |journal=Proceedings of the National Academy of Sciences |volume=37 |issue=1 |page=233 |doi=10.1073/pnas.37.4.233 |pmc=1063291 |pmid=16588984 |doi-access=free}}</ref> It is said that Kuiper was operating on the assumption, common in his time, that [[Pluto]] was the size of Earth and had therefore scattered these bodies out toward the [[Oort cloud]] or out of the Solar System; there would not be a Kuiper belt today if this were correct.<ref name="Jewitt2">{{cite web |author=David Jewitt |title=WHY "KUIPER" BELT? |url=http://www2.ess.ucla.edu/~jewitt/kb/gerard.html |url-status=live |archive-url=https://web.archive.org/web/20190212100219/http://www2.ess.ucla.edu/~jewitt/kb/gerard.html |archive-date=12 February 2019 |access-date=14 June 2007 |work=University of Hawaii}}</ref> The name "Kuiper belt" was given to the region in the 1980s;<ref>{{cite journal |author=J.A. Fernández |date=1980 |title=On the existence of a comet belt beyond Neptune |journal=Monthly Notices of the Royal Astronomical Society |volume=192 |issue=3 |pages=481–491 |bibcode=1980MNRAS.192..481F |doi=10.1093/mnras/192.3.481 |doi-access=free}}</ref> it was first used in print by [[Scott Tremaine]] in 1988.<ref name="Davies_2001">{{cite book |last=Davies |first=John K. |title=Beyond Pluto: Exploring the outer limits of the solar system |date=2001 |publisher=Cambridge University Press}}</ref>{{rp|page=191}}

In the 1960s, Kuiper helped identify [[moon landing|landing]] sites on the [[Moon]] for the [[Apollo program]].{{efn|Cameras in [[Ranger 8|Ranger VIII]] were turned on 23&nbsp;minutes before impact, and the spacecraft transmitted pictures back to earth until it struck the surface and was destroyed. The flight's product would be intensively studied by a panel of noted lunar scientists, among them Gerard P. Kuiper and [[Ewen Whitaker|Ewen A. Whitaker]] of the University of Arizona and [[Harold Urey|Harold C. Urey]] of the University of California. &nbsp; &nbsp; — Brooks & Ertel (1976, p.&nbsp;75)<ref name="brooks1976">{{cite book |first1=Courtney G. |last1=Brooks |last2=Ertel |first2=Ivan D. |title=The Apollo Spacecraft: A chronology |date=1976 |department=Scientific and Technical Information Division, Office of Technology Use |publisher=National Aeronautics and Space Administration (NASA) |page=[https://books.google.com/books?id=mBpdI_bqMFEC&pg=PA75 75] |url=https://books.google.com/books?id=mBpdI_bqMFEC&pg=PA75 |language=en}}</ref>}}

Kuiper discovered several binary stars which received "Kuiper numbers" to identify them, such as KUI&nbsp;79.

== Personal life and death ==
He married Sarah Parker Fuller (1913-2000) on 20&nbsp;June 1936. Kuiper died age 68 of a heart attack on 23&nbsp;December 1973 in [[Mexico City]],<ref>{{Cite news |date=1973-12-25 |title=Dr. Gerard Kuiper, Astronomer, Dies (Published 1973) |url=https://www.nytimes.com/1973/12/25/archives/dr-gerard-kuiper-astronomer-dies-predicted-moon-surface-essentially.html |access-date=2025-08-31 |language=en}}</ref><ref>{{Cite web |title=Who was Gerard Kuiper? |url=https://www.universetoday.com/articles/gerard-kuiper |access-date=2025-08-31 |website=Universe Today |language=en}}</ref> while on vacation with his wife.<ref>{{cite web |last=Williams |first=Matt |date=11 November 2015 |title=Who was Gerard Kuiper? |website=Universe Today |language=en-US |url=https://www.universetoday.com/91203/gerard-kuiper/ |access-date=24 March 2020}}</ref>

==Honors==
[[File:University of Arizona May 2019 37 (Gerard P. Kuiper Space Sciences).jpg|thumb|right|Gerard P. Kuiper Space Sciences building at the [[University of Arizona]]]]

* In 1947, Kuiper was awarded the [[Prix Jules Janssen]] of the [[Société astronomique de France]] (Astronomical Society of France).
* In 1959, Kuiper won the [[Henry Norris Russell Lectureship]] of the [[American Astronomical Society]].
*In 1971, Kuiper received the Kepler Gold Medal from the American Association for the Advancement of Science and the Franklin Institute.

Besides the [[minor planet]] [[1776 Kuiper]], three craters ([[Kuiper (Mercurian crater)|Mercurian]], [[Kuiper (lunar crater)|lunar]], and [[Kuiper (Martian crater)|Martian]]), [[Kuiper Scarp]] in Antarctica, and the now-decommissioned [[Kuiper Airborne Observatory]] were also named after him.

Astronomers refer to a region of [[minor planet]]s beyond Neptune as the "[[Kuiper belt]]," since Kuiper had suggested that such small planets or comets may have formed there. However Kuiper himself believed that such objects would have been swept clear by planetary gravitational perturbations, so that none or few would exist there today.{{citation needed|date=August 2020}}

The [[Kuiper Prize]], named in his honor, is the most distinguished award given by the [[American Astronomical Society]]'s [[Division for Planetary Sciences]], an international society of professional planetary scientists.{{efn|The [[Kuiper Prize]] recognizes outstanding contributors to [[planetary science]], and is awarded annually to scientists whose lifetime achievements have most advanced our understanding of planetary systems. Winners of this award include [[Carl Sagan]], [[James Van Allen]], and [[Eugene Shoemaker]].}}

One of the three buildings at Arizona that makes up the Lunar and Planetary Laboratory is named in his honor.<ref>{{Cite web |url=https://www.lpl.arizona.edu/about/history/overview |title=A Brief History of LPL |publisher=[[University of Arizona]] |access-date=2024-06-01}}</ref>

In Tuitjenhorn is since 2001 a statue of Gerard Kuiper, made by Gosse Dam.<ref>https://www.vanderkrogt.net/standbeelden/object.php?record=NH44bb</ref>

==In popular culture==
Episode 6 ("The Man of a Trillion Worlds") of the TV series ''[[Cosmos: Possible Worlds]]'' featured the Kuiper–Urey conflict.<ref>{{Cite web |last=Graney |first=Christopher |date=2020-11-21 |title=“Cosmos: Possible Worlds”, 4-6: Screaming from the Bleachers |url=https://www.vaticanobservatory.org/sacred-space-astronomy/cosmos-possible-worlds-4-6-screaming-from-the-bleachers/ |access-date=2025-08-27 |website=Vatican Observatory |language=en-US}}</ref>

==Notes==
{{notelist}}

==References==
{{reflist|25em}}

==External links==
*{{Commons category-inline}}
* {{cite web |title=Gerard Peter Kuiper: NASA KAO's namesake |series=Biography |url=http://quest.arc.nasa.gov/lfs/kuiper-bio.html |publisher=National Aeronautics and Space Administration (NASA) |url-status=dead |archive-url=https://web.archive.org/web/20140713130039/http://quest.arc.nasa.gov/lfs/kuiper-bio.html |archive-date=13 July 2014}}
* {{cite web |url=http://www.azarchivesonline.org/xtf/view?docId=ead/uoa/UAMS480.xml |title=Gerard Kuiper Papers |series=Archive |publisher=University of Arizona |website=AzArchivesOnline.org}}
* {{cite web |title=Gerard Peter Kuiper, 1905—1973 |publisher=National Academy of Sciences |author=Dale P. Cruikshank |series=Biographical Memoir |url=http://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/kuiper-gerard.pdf}}

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{{DEFAULTSORT:Kuiper, Gerard}}
[[Category:Gerard Kuiper| ]]
[[Category:1905 births]]
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[[Category:20th-century American astronomers]]
[[Category:American science writers]]
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[[Category:20th-century Dutch astronomers]]
[[Category:Dutch science writers]]
[[Category:Dutch essayists]]
[[Category:Dutch encyclopedists]]
[[Category:Dutch emigrants to the United States]]
[[Category:Discoverers of moons]]
[[Category:Planetary scientists]]
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