Yoshihide KOZAI

Japan

1928-2018

Obituary:

Dr. Yoshihide Kozai Former IAU President and Director General of NAOJ Passes Away

Dr. Yoshihide Kozai, Professor Emeritus of the National Astronomical Observatory of Japan (NAOJ), founding Director General of NAOJ and former IAU President, passed away due to liver failure at 6:15 p.m. on Monday, February 5, 2018, at age 89.

Dr. Yoshihide Kozai was a global leader in the field of astronomy. He highly contributed to the development of astronomy in Japan, Asia and whole world. Dr. Kozai started his career as an astronomer at the Tokyo Astronomical Observatory, University of Tokyo in 1952. He also served as a Visiting Researcher of the Smithsonian Astrophysical Observatory from1958 to 1962. He was appointed Director of TAO in 1981, and led the operational reformation of TAO toward a modern astronomical institute, including its reorganization into an Inter-University Research Institute, NAOJ (National Astronomical Observatory of Japan) in 1988. He served as the founding Director General of NAOJ until 1994. During this time he conducted a wide variety of important activities, such as starting the 8.2 meter aperture Subaru Telescope project on Mauna-Kea as Japan’s first large overseas research facility, and serving as the first ever Japanese President of the International Astronomical Union (IAU) from 1988-1991, etc.

He is known worldwide in the research field of celestial mechanics for his work on the motion of artificial satellites. He had many important achievements, such as proposing “Kozai’s equations” which are still used for satellite orbit calculations and based on that he discovered the North-South asymmetry of the Earth (the so called “Pear Shape”). He also proposed the kinematic mechanism by which asteroids in inclined or elliptical orbits experience large changes in their orbits due to the gravity of the planets. This principle is known as the “Kozai mechanism” which is widely used now for the dynamical evolution of exoplanet systems. For these achievements, he received the Imperial Prize and the Japan Academy Prize in 1979, American Astronomical Society Brouwer Award in 1990, Second Class Order of the Sacred Treasure in 2002, and Person of Cultural Merit in 2009.

He chaired the 4th Asian-Pacific IAU Regional Meeting, Beijing in 1987, and invited North Korean astronomers for the first time. In 1991 he led the successful organization of the IAU GA in Buenos Aires as IAU President. After retiring from NAOJ he continued his contributions to the astronomical community as Director of Gunma Astronomical Observatory; he powerfully supported young Asian astronomers, and worked to improve the situation of female researchers as a member of the Science Council of Japan. We will not forget his friendly interactions with amateur astronomers, writing books for the public and serving on the editorial committee for astronomy magazines, etc. Professor Yoshihide Kozai was really a great astronomer and a kindhearted person.

We respectfully mourn his passing.

Norio Kaifu: Professor Emeritus, NAOJ, and Advisor to the IAU
Masahiko Hayashi: Director General, NAOJ
Hiroshi Kinoshita: Professor Emeritus, NAOJ

https://www.nao.ac.jp/en/news/announcements/2018/20180213-kozai.html