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 their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

and educator.

Biography

Leuschner was born on January 16, 1868, in the United States but raised in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

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

University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...

in 1888 with a degree in mathematics. Leuschne 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, in the Diablo Range just east of San Jose, California, United States. The observatory is managed by th ...

, 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 Humboldt-Universität zu Berlin (german: Humboldt-Universität zu Berlin, abbreviated HU Berlin) is a German public research university in the central borough of Mitte in Berlin. It was established by Frederick William III on the initiative o ...

, where in 1897 he earned his doctorate with a highly praised thesis on the orbits of comets. He 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 land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...

, 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 James Edward Keeler (September 10, 1857 – August 12, 1900) was an American astronomer. He was an early observer of galaxies using photography, as well as the first to show observationally that the rings of Saturn do not rotate as a solid body ...

, 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 of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

s and

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

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 five dozen students received their doctorates 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 (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

related training at the university. He was a founding member of the Astronomical Society of the Pacific, 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. AAUP membership includes over 500 local campus chapters and 39 state organizations. The AAUP's stated mission is ...

, and chaired the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

'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 S ...

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 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. National Academy of Scienc ...

(1916) *

Order of the North Star The Royal Order of the Polar Star (Swedish: ''Kungliga Nordstjärneorden'') is a Swedish order of chivalry created by King Frederick I on 23 February 1748, together with the Order of the Sword and the Order of the Seraphim. The Order of the ...

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

(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 firs ...

(1936) *

Rittenhouse Medal The Rittenhouse Medal is awarded by the Rittenhouse Astronomical Society for outstanding achievement in the science of Astronomy. The medal was one of those originally minted to commemorate the Bi-Centenary of the birth of David Rittenhouse on April ...

(1937) *

Halley Lecturer Halley may refer to: Science * Halley's Comet, officially designated 1P/Halley, a comet that becomes visible from Earth every 75-76 years * Halley (lunar crater), a lunar crater named after Edmond Halley * Halley (Martian crater), a Martian cra ...

University of Oxford , mottoeng = The Lord is my light , established = , endowment = £6.1 billion (including colleges) (2019) , budget = £2.145 billion (2019–20) , chancellor ...

(1938) Named after him *

Leuschner (crater) Leuschner is a Lunar craters, lunar impact crater that is located on the Moon's Far side (Moon), far side, to the northwest of the Montes Cordillera. It lies to the north of the crater Grachev (crater), Grachev, in the outer skirt of ejecta sur ...

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 ...

* Main-belt asteroid 1361 Leuschneria * Asteroid

718 Erida 718 Erida is a minor planet orbiting the Sun. It was discovered at Vienna on September 29, 1911, by Austrian astronomer Johann Palisa, and was named for Erida Leuschner, daughter of astronomer Armin Otto Leuschner. It is orbiting at a distance of ...

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 in the center of the campus of the University of California, Berkeley, is the university's primary special-collections library. It was acquired from its founder, Hubert Howe Bancroft, in 1905, with the proviso that it retai ...

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