Kiyotsugu Hirayama | |
|---|---|
平山 清次 | |
| Born | October 3, 1874 Sendai, Japan |
| Died | April 8, 1943(1943-04-08) (aged 68) Tokyo, Japan |
| Alma mater | Tokyo Imperial University |
| Known for | Hirayama families |
| Scientific career | |
| Notable students | Yoshio Fujita |
Kiyotsugu Hirayama (平山 清次,Hirayama Kiyotsugu; October 3, 1874 – April 8, 1943) was a Japaneseastronomer, best known for his discovery that manyasteroid orbits were more similar to one another than chance would allow, leading to the concept of asteroid families, now called "Hirayama families" in his honour.[1]
Hirayama studied astronomy atImperial University of Tokyo and graduated in 1897. He taught astronomy in the engineering school of the General Staff Office of the Japanese Army between 1897 and 1901. In 1906 he became Assistant Professor of Astronomy at Tokyo Imperial University; in 1919 he became a Professor. From 1906 to 1907 Hirayama was a member of the Committee that determined the latitude border atSakhalin after theRusso–Japanese War. In 1911 he received a doctoral degree "with several papers about latitude variation". Hirayama started working on asteroids in 1905; in 1918 he published papers "Researches on the distribution of the mean motions of the asteroids" and "Groups of asteroids probably of common origin", and, later "Families of asteroids" (1922) and "Note on an explanation of the gaps of the asteroidal orbits" (1928). In 1935 he published his main work,Asteroid.[1]
The craterHirayama on theMoon is jointly named after him andShin Hirayama. The asteroid1999 Hirayama is named in his honour.[2]
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