Seth Barnes Nicholson

Seth Barnes Nicholson (born November 12, 1891 in Springfield , Illinois , † July 2, 1963 in Los Angeles ) was an American astronomer .

Life

Nicholson grew up in rural Illinois and later attended Drake University, where his interest in astronomy was aroused.

In 1914, at the University of California's Lick Observatory , he observed the newly discovered moon of Jupiter , later named Pasiphae . He discovered another moon near Jupiter ( Sinope ), which was named Jupiter moon IX . Nicholson calculated the orbit of the moon in 1915 as part of his doctoral thesis . In 1916 he discovered the asteroid (878) Mildred .

He continued his professional life at the Mount Wilson Observatory , where he discovered three other moons of Jupiter, Lysithea , Carme (both 1938) and Ananke (1951) and the Trojan asteroid (1647) Menelaus . He also calculated the orbits of several comets and the dwarf planet Pluto .

Sinope, Lysithea, Carme and Ananke were initially referred to simply as the moons of Jupiter IX, X, XI and XII. It was not until 1975 that they received their names from the International Astronomical Union (IAU), whereby Nicholson had spoken out against a name being given.

His main job at the Mount Wilson Observatory, however, was the study of solar activity , and for decades he produced annual reports on sunspot activities. He took part in several expeditions to observe solar eclipses to determine the brightness and temperature of the sun's corona .

In the early 1920s, he and Edison Pettit carried out the first systematic investigations of celestial bodies in the infrared range. The measurement of the infrared radiation of the earth's moon and the temperatures derived from it led to the correct assumption that the moon's surface is covered with a thin layer of dust, which has a heat-insulating effect. The temperature measurements of red giant stars gave first indications for the determination of star diameters.

In 1937 Barnes was elected to the National Academy of Sciences . From 1943 to 1955, he served as editor and vice president for the Astronomical Society of the Pacific . In 1963 he was awarded the Bruce Medal for his services .

Asteroid discoveries : 2

(878) Mildred	September 6, 1916
(1647) Menelaus	June 23, 1957

The asteroid (1831) Nicholson , the lunar crater Nicholson , the Mars crater Nicholson and the Nicholson region on Jupiter's moon Ganymede are named after him.

literature

• John Daintith, Sarah Mitchell, E. Tootill, D. Gjertsen: Biographical encyclopedia of scientists . CRC Press. ISBN 0-7503-0287-9

Web links

• Publications by SB Nicholson in the Astrophysics Data System
• Laudation for SB Nicholson on the occasion of the award of the Bruce Medal