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Seth Barnes Nicholson | |
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| Born | (1891-11-12)November 12, 1891 Springfield, Illinois, U.S. |
| Died | July 2, 1963(1963-07-02) (aged 71) Los Angeles, California, U.S. |
| Alma mater | Drake University |
| Awards | Bruce Medal (1963) |
| Scientific career | |
| Fields | astronomy |
| Institutions | Mount Wilson Observatory |
Seth Barnes Nicholson (November 12, 1891 – July 2, 1963) was an Americanastronomer.[1] He worked at the Lick observatory in California, and is known for discovering several moons of Jupiter in the 20th century.
| Asteroids discovered: 2 | |
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| 878 Mildred | September 6, 1916 |
| 1647 Menelaus | June 23, 1957 |
Nicholson was born inSpringfield, Illinois, and was raised in rural Illinois. He was educated atDrake University, where he became interested in astronomy.[2] On May 29, 1913, he was married to Alma Stotts, a fellow student at Drake then the University of California at Berkeley. They would have three children: Margaret, Donald, and Jean.[3]
In 1914, at the University of California'sLick Observatory, while observing the recently discoveredJupitermoonPasiphaë, he discovered a new one,Sinope, whoseorbit he computed for his Ph.D. thesis in 1915.
He spent his entire career atMount Wilson Observatory, where he discovered three more Jovian moons:Lysithea andCarme in 1938, andAnanke in 1951. While at thePalomar Observatory in 1957, he discovered1647 Menelaus, an asteroid near Jupiter. Other work included computing the orbits of severalcomets and also that ofPluto.
Sinope, Lysithea, Carme, and Ananke were simply designated as "Jupiter IX", "Jupiter X", "Jupiter XI", and "Jupiter XII". They were not given their present names until 1975. Nicholson himself declined to propose names.[4]
At Mt. Wilson, his main assignment concernedsolar activity and he produced for decades annual reports onsunspot activity. He also made a number ofeclipse expeditions to measure the brightness and temperature of theSun's corona.
In the early 1920s, he andEdison Pettit made the first systematicinfrared observations of celestial objects.They used a vacuumthermocouple to measure the infrared radiation and thus the temperature of theMoon which led to the theory that the Moon was covered with a thin layer of dust acting as an insulator, and also of the planets, sunspots and stars.Their temperatures measurements of nearbygiant stars led to some of the first determinations of stellar diameters.
Nicholson, together with astronomerGeorge Ellery Hale, lend their name to the "Hale-Nicholson law" concerning the magnetic polarity of sunspots.[5][6]
From 1943 to 1955, he served as editor of thePublications of theAstronomical Society of the Pacific, of which he was also twice president.
He died inLos Angeles. His final resting place is in dispute, but he was cremated and his remains were likely dispersed by his son.
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