Armin Otto Leuschner (January 16, 1868 – April 22, 1953) was an American

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

and educator.

Early life and education

Leuschner was born on January 16, 1868, in

Detroit, Michigan Detroit ( , ) is the List of municipalities in Michigan, most populous city in the U.S. state of Michigan. It is situated on the bank of the Detroit River across from Windsor, Ontario. It had a population of 639,111 at the 2020 United State ...

,LEUSCHNER, Armin Otto
in '' Marquis Who's Who in America'', 1901-1902 edition; via

archive.org The Internet Archive is an American non-profit organization founded in 1996 by Brewster Kahle that runs a digital library website, archive.org. It provides free access to collections of digitized media including websites, software applic ...

but raised in

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

. He returned to the United States for university studies, graduating from the

University of Michigan The University of Michigan (U-M, U of M, or Michigan) is a public university, public research university in Ann Arbor, Michigan, United States. Founded in 1817, it is the oldest institution of higher education in the state. The University of Mi ...

in 1888 with a degree in mathematics. Leuschner then became the first graduate student at

Lick Observatory The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton (California), Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The ...

, but due to conflicts with his advisor, Lick director Edward S. Holden, he left Lick before finishing his Ph.D. Leuschner subsequently returned to Germany and attended the

University of Berlin The Humboldt University of Berlin (, abbreviated HU Berlin) is a public research university in the central borough of Mitte in Berlin, Germany. The university was established by Frederick William III on the initiative of Wilhelm von Humbol ...

, where in 1897 he earned his doctorate with a highly praised thesis on the orbits of comets.

Career

Leuschner returned to California as an associate professor in astronomy at

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a Public university, public Land-grant university, land-grant research university in Berkeley, California, United States. Founded in 1868 and named after t ...

, where he remained for over half a century. He founded an observatory there for student instruction, later renamed in his honor

Leuschner Observatory Leuschner Observatory, originally called the Students' Observatory, is an observatory jointly operated by the University of California, Berkeley and San Francisco State University. The observatory was built in 1886 on the Berkeley campus. For many ...

. Together with Lick director James E. Keeler, Leuschner shaped the combined graduate program at Berkeley and Lick into one of the nation's foremost centers of astronomical education. Leuschner's own research continued to focus on the orbits of

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

s and

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

s; this subject required tremendous amounts of detailed computation, which made the work well-suited to be shared with a long series of students, many of whom went on to successful astronomical careers of their own. More than sixty students received their doctorate under Leuschner's guidance. In 1913, Leuschner became dean of the entire Graduate School at Berkeley, and later was appointed head of all

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

related training at the university. He was a founding member of the

Astronomical Society of the Pacific The Astronomical Society of the Pacific (ASP) is an American scientific and educational organization, founded in San Francisco on February 7, 1889, immediately following the solar eclipse of January 1, 1889. Its name derives from its origins on ...

, served a term as the president of the

American Association of University Professors The American Association of University Professors (AAUP) is an organization of professors and other academics in the United States that was founded in 1915 in New York City and is currently headquartered in Washington, D.C. AAUP membership inc ...

, and chaired the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

's committee on comets and minor planets for two decades. Leuschner was one of the first astronomers to dispute

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

as being

Planet X Following the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began in the mid-19th century and continued at the start of the 20th with Percival Lowell's ...

as predicted by Lowell. By 1932 he was already suggesting that Pluto had a mass less than the Earth, and that the discovery of Pluto was an accidental by-product of the Lowell search. 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

Honors

Awards *

James Craig Watson Medal image:Watson_medal_NAS.gif, 400px, James Craig Watson Medal The James Craig Watson Medal was established by the bequest of James Craig Watson, an astronomer the University of Michigan between 1863 and 1879, and is awarded every 1-4 years by the U.S. ...

(1916) *

Order of the North Star The Royal Order of the Polar Star (Swedish language, Swedish: ''Kungliga Nordstjärneorden''), sometimes translated as the Royal Order of the North Star, is a Swedish order of chivalry created by Frederick I of Sweden, King Frederick I on 23 F ...

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

(1924) *

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 ...

(1936) * Rittenhouse Medal (1937) * Halley Lecturer,

University of Oxford The University of Oxford is a collegiate university, collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the List of oldest un ...

(1938) Honors * Member of the United States

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

(1913) * Member of the

American Philosophical Society The American Philosophical Society (APS) is an American scholarly organization and learned society founded in 1743 in Philadelphia that promotes knowledge in the humanities and natural sciences through research, professional meetings, publicat ...

(1924) Named after him * Leuschner (crater) on the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

* Main-belt asteroid 1361 Leuschneria * Asteroid 718 Erida is named after his daughter Erida Leuschner.

References

External links

Denies Planet Really Found
(Sarasota Herald April 15, 1930)
Armin Otto Leuschner papers, 1875–1951
at

The Bancroft Library The Bancroft Library is the primary special-collections library of the University of California, Berkeley. It was acquired from its founder, Hubert Howe Bancroft, in 1905, with the proviso that it retain the name Bancroft Library in perpetuity. ...

National Academy of Sciences Biographical MemoirPortrait of Armin Otto Leuschner from the Lick Observatory Records Digital Archive, UC Santa Cruz Library's Digital Collections
{{DEFAULTSORT:Leuschner, Armin 1868 births 1953 deaths American astronomers University of Michigan College of Literature, Science, and the Arts alumni Humboldt University of Berlin alumni University of California, Berkeley faculty Order of the Polar Star Presidents of the American Association of University Professors Members of the American Philosophical Society