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28-471: Spacewatch was founded in 1980 by Tom Gehrels and Robert S. McMillan , and is currently led by astronomer Melissa Brucker at the University of Arizona . Spacewatch uses several telescopes on Kitt Peak for follow-up observations of near-Earth objects . The Spacewatch Project uses three telescopes of apertures 0.9-m, 1.8-m, and 2.3-m. These telescopes are located on Kitt Peak, and the first two are dedicated to

56-538: 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. In 1951, in

84-790: A heart attack on 23 December 1973 in Mexico City , while on vacation with his wife. Besides the minor planet 1776 Kuiper , three craters ( Mercurian , lunar , and Martian ), Kuiper Scarp in Antarctica, and the now-decommissioned Kuiper Airborne Observatory were also named after him. Astronomers refer to a region of minor planets 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. The Kuiper Prize , named in his honor,

112-549: 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." In another paper, based upon a lecture Kuiper gave in 1950, also called On

140-616: 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 McDonald Observatory in west Texas. In 1949, Kuiper initiated the Yerkes–McDonald asteroid survey (1950–1952). From 1950-1960 he was professor at the University of Chicago , directing the Yerkes Observatory . He was doctoral advisor to Carl Sagan . In 1958,

168-493: Is named after him. Kuiper is considered by many to be the father of modern planetary science . 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 magnitude 7.5 stars, about four times fainter than those visible to normal eyes. He studied at Leiden University in 1924, where at

196-458: Is used exclusively for asteroids and comets. It can find asteroids and comets anywhere from the space near Earth to regions beyond the orbit of Neptune and to do astrometry on the fainter of objects that are already known. The telescope is pointed on stars and tracked with a real time video-rate camera at folded prime focus. Spacewatch was the first to use CCDs to survey the sky for comets and asteroids. When added, they permitted faster coverage of

224-651: The Oort cloud or out of the Solar System; there would not be a Kuiper belt today if this were correct. The name "Kuiper belt" was given to the region in the 1980s; it was first used in print by Scott Tremaine in 1988. In the 1960s, Kuiper helped identify landing sites on the Moon for the Apollo program . Kuiper discovered several binary stars which received "Kuiper numbers" to identify them, such as KUI 79. He married Sarah Parker Fuller on 20 June 1936. Kuiper died age 68 of

252-551: The University of Arizona , serving as the laboratory's director for the rest of his life, until his death in 1973. Kuiper discovered two natural satellites of planets in the Solar System , namely Uranus 's satellite Miranda and Neptune 's satellite Nereid . In addition, he discovered carbon dioxide in the atmosphere of Mars , and the existence of a methane -laced atmosphere above Saturn 's satellite Titan in 1944. Kuiper also pioneered airborne infrared observing using

280-594: The 1970s. Gehrels initiated the Space Science Series of textbooks, was General Editor for the first 30 volumes of the University of Arizona Press, and set the style by participating in the editing of six of them. He also initiated the Spacewatch program in 1980 and was its Principal Investigator (PI) for electronic surveying to obtain statistics of asteroids and comets, including near-Earth asteroids . Bob McMillan

308-456: The German forces. After the war, he attended the University of Leiden where he graduated with a degree in physics and astronomy in 1951. He continued his education at the University of Chicago where he obtained his doctorate in astronomy and astrophysics in 1956 under Professor Gerard P. Kuiper . In 1960, he moved to the University of Arizona along with Gerard Kuiper where he would remain for

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336-566: The Netherlands on February 21, 1925. He was born in bible-belt Netherlands, and was forced to attend church regularly, an act he despised. When he was older he rejoiced when he found out his childhood church had been destroyed. During World War II he was, as a teenager, active in the Dutch Resistance . After he escaped to England , he was sent back by parachute as an organizer for Special Operations Executive SOE committing sabotage against

364-597: The Netherlands on his thesis on binary stars with Hertzsprung in 1933. 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 June 1936. Although he had planned to move to Java to work at the Bosscha Observatory , he took

392-484: 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 2 0, NH 3 , CH 4 , 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

420-411: The comets, in size, number and composition." According to Kuiper "the planet Pluto, which sweeps through the whole zone from 30 to 50 astr. units , is held responsible for having started the scattering of the comets throughout the solar system." 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

448-447: The end of the book review it reads: Von Braun needs no phony defense, for he was a great man in his own scientific specialization... What is needed is a more sophisticated historical perspective... . Tom Gehrels was the husband of Aleida J. Gehrels (née de Stoppelaar) and father of Neil Gehrels , George Gehrels and Jo-Ann Gehrels. He died in Tucson, Arizona. The minor planet 1777 Gehrels

476-514: The named winner of the 2007 Harold Masursky Award for his outstanding service to planetary science. Gehrels was requested by the Journal Nature to write a review on a book regarding Wernher von Braun , in which he quotes inmates of concentration camp Dora . He has therefore charged that von Braun was there regularly and much in charge, and that von Braun bears greater responsibility and guilt than his official biography would imply. Towards

504-567: The next 50 years. Gehrels pioneered the first photometric system of asteroids in the 1950s, and wavelength dependence of polarization of stars and planets in the 1960s, each resulting in an extended sequence of papers in the Astronomical Journal . He discovered, jointly with the husband and wife team of Cornelis Johannes van Houten and Ingrid van Houten-Groeneveld , over 4000 asteroids , including Apollo asteroids , Amor asteroids , as well as dozens of Trojan asteroids . That

532-462: The purpose of finding previously unknown asteroids and comets. Since January 1 2003, Spacewatch has made ~2400 separate-night detections of Near-Earth Objects. There was an upgrade to the 0.9 meter which was funded by NASA and the Kirsch Foundation. The Spacewatch Project is the longest-running of all present programs of astrometry of solar system objects. Spacewatch conducted a survey that

560-405: The purpose of locating Near-Earth Objects (NEOs) . The 36 inch (0.9 meter) telescope on Kitt Peak has been in use by Spacewatch since 1984, and since 2000 the 72 inch (1.8 meter) Spacewatch telescope. The 36 inch telescope continued in use and was further upgraded, in particular, the telescopes use electronic detectors. Spacewatch's 1.8-meter telescope is the largest in the world that

588-424: The sky are productive even if they have been previously examined simply due to the complexities of running large surveys over many nights and variable conditions. Tom Gehrels Anton M.J. " Tom " Gehrels (February 21, 1925 – July 11, 2011) was a Dutch–American astronomer , Professor of Planetary Sciences, and Astronomer at the University of Arizona , Tucson. Gehrels was born at Haarlemmermeer ,

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616-582: The sky than the pre-2002 system. Each year, Spacewatch observes approximately 35 radar targets, 50 near-Earth objects , and 100 potential spacecraft rendezvous destinations. From 2013 to 2016, Spacewatch observed half of all NEOs and potentially hazardous asteroids (PHAs) observed by anyone in that time. As of 2022, Spacewatch had discovered over 179,000 minor planets numbered by the Minor Planet Center . The 1.8 meter Spacewatch telescope and its building on Kitt Peak were dedicated on June 7, 1997 for

644-489: 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 , Jan Oort , and the physicist Paul Ehrenfest . He received his candidate degree in Astronomy in 1927 and continued straight on with his graduate studies. Kuiper received his PhD degree from Leiden University in

672-604: The two worked on the classified military Project A119 , a secret Air Force plan to detonate a nuclear warhead on the moon. In 1959, he sent 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 . In 1960 Kuiper moved to Tucson , Arizona , to found the Lunar and Planetary Laboratory at

700-664: Was co-investigator and manager, and became the PI in 1997. Gehrels taught an undergraduate course for non-science majors in Tucson in the Fall, and lectured a brief version of that in the Spring at the Physical Research Laboratory in Ahmedabad , India. His recent research was on cosmology and evolution of the universe , which was woven in as the guiding thread through these courses. He was

728-580: Was done in a sky survey using the 48-inch Schmidt telescope at Palomar Observatory and shipping the plates to the two Dutch astronomers at Leiden Observatory , who analyzed them for new asteroids. The trio are jointly credited with several thousand discoveries. Gehrels also discovered a number of comets . He was Principal Investigator for the Imaging Photopolarimeter experiment on the Pioneer 10 and Pioneer 11 first flybys of Jupiter and Saturn in

756-449: Was named in his honour. The professional and personal papers of Tom Gehrels are held at the University of Arizona. Gerard P. Kuiper Gerard Peter Kuiper ( / ˈ k aɪ p ər / KY -pər ; born Gerrit Pieter Kuiper , Dutch: [ˈɣɛrɪt ˈpitər ˈkœypər] ; 7 December 1905 – 23 December 1973) was a Dutch-American astronomer , planetary scientist , selenographer , author and professor. The Kuiper belt

784-436: Was proposed May 12, 2006, and accepted on November 13, 2006. This survey used data taken over 34 months by the University of Arizona ’s Spacewatch Project based at Steward Observatory , Kitt Peak. Spacewatch revisited the same sky area every three to seven nights in order to track cohorts of main-belt asteroids. This survey discovered one new large Kuiper Belt Object (KBO) and detected six others. This proved that new sweeps of

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