The Most Famous

ASTRONOMERS from Japan

This page contains a list of the greatest Japanese Astronomers. The pantheon dataset contains 644 Astronomers, 20 of which were born in Japan. This makes Japan the birth place of the 7th most number of Astronomers behind Italy, and Netherlands.

Top 10

The following people are considered by Pantheon to be the top 10 most legendary Japanese Astronomers of all time. This list of famous Japanese Astronomers is sorted by HPI (Historical Popularity Index), a metric that aggregates information on a biography’s online popularity. Visit the rankings page to view the entire list of Japanese Astronomers.

1. Takeshi Urata (1947 - 2012)

With an HPI of 50.45, Takeshi Urata is the most famous Japanese Astronomer. His biography has been translated into 27 different languages on wikipedia.

Takeshi Urata (浦田武, Urata Takeshi, 1947 – December 15, 2012) was a Japanese astronomer. He was a prolific discoverer of asteroids, observing at Nihondaira Observatory. In 1978 he became the first amateur to discover a minor planet (2090 Mizuho) in over fifty years, which he named after his daughter, Mizuho. His pioneering feat led to an upsurge in such discoveries. In the ten years that followed, amateurs from Japan discovered 160 minor planets. Urata shared his observation data with peer astronomers in Japan on a periodical called "Tenkai" (the Heavens), as well as contributed to academic journals such as Advances in Space Research and participated in poster presentations at astronomical conferences. Urata co-discovered the periodic comet 112P/Urata-Niijima in 1986. One of the most active amateur astronomers in Japan, he was also an editor of the Japanese Ephemerides of Minor Planets. The 1927-discovered asteroid 3722 Urata is named after him.

2. Kiyotsugu Hirayama (1874 - 1943)

With an HPI of 50.13, Kiyotsugu Hirayama is the 2nd most famous Japanese Astronomer. His biography has been translated into 19 different languages.

Kiyotsugu Hirayama (平山清次, Hirayama Kiyotsugu, October 3, 1874 – April 8, 1943) was a Japanese astronomer, best known for his discovery that many asteroid 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.

3. Chushiro Hayashi (1920 - 2010)

With an HPI of 49.44, Chushiro Hayashi is the 3rd most famous Japanese Astronomer. His biography has been translated into 21 different languages.

Chushiro Hayashi (林忠四郎, Hayashi Chūshirō, July 25, 1920 – February 28, 2010) was a Japanese astrophysicist. Hayashi tracks on the Hertzsprung–Russell diagram are named after him. Hayashi was born in Kyoto and enrolled at the Imperial University of Tokyo in 1940, earning his BSc in Physics after 2½ years, in 1942. He was conscripted into the navy and, after the war ended, joined the group of Hideki Yukawa at Kyoto University. He was appointed a professor at Kyoto University in 1957. He made additions to the Big Bang nucleosynthesis model that built upon the work of the classic Alpher–Bethe–Gamow paper. Probably his most famous work was the astrophysical calculations that led to the Hayashi tracks of star formation, and the Hayashi limit that puts a limit on star radius. He was also involved in the early study of brown dwarfs, some of the smallest stars formed. He retired in 1984 and died from pneumonia at a Kyoto hospital on February 28, 2010.

4. Tsutomu Seki (b. 1930)

With an HPI of 47.12, Tsutomu Seki is the 4th most famous Japanese Astronomer. His biography has been translated into 25 different languages.

Tsutomu Seki (関勉, Seki Tsutomu, born November 3, 1930) is a Japanese amateur astronomer and discoverer of minor planets and comets, born in Kōchi, Japan.

5. Hiroshi Kaneda (b. 1953)

With an HPI of 46.78, Hiroshi Kaneda is the 5th most famous Japanese Astronomer. His biography has been translated into 19 different languages.

Hiroshi Kaneda (金田宏, Kaneda Hiroshi, born 1953) is a Japanese astronomer and discoverer of minor planets from Sapporo, in the northernmost prefecture of Japan. Kaneda ranks among the world's most prolific individual discoverers of minor planets. He is credited by the Minor Planet Center with the co-discovery of 705 numbered minor planets, between 1987 and 2000, all of them in collaboration with astronomer Seiji Ueda. Along with being an astronomer, Kaneda works as a computer programmer and is a developer of astronomical software. The main-belt asteroid 4677 Hiroshi, discovered by Atsushi Takahashi and Kazurō Watanabe at Kitami in 1990, is named after him.

6. Hiroki Kosai (b. 1933)

With an HPI of 46.41, Hiroki Kosai is the 6th most famous Japanese Astronomer. His biography has been translated into 19 different languages.

Hiroki Kosai (香西洋樹, Kōsai Hiroki, born 8 February 1933) is a Japanese astronomer with the Kiso Observatory. He is best known for helping to popularize astronomy in Japan and for his observations of comets and asteroids, most notably with his co-discovery the comet 1976 XVI. He is credited by the Minor Planet Center (MPC) with the discovery of nearly 100 asteroids.

7. Yuji Hyakutake (1950 - 2002)

With an HPI of 46.02, Yuji Hyakutake is the 7th most famous Japanese Astronomer. His biography has been translated into 19 different languages.

Yuji Hyakutake (百武裕司, Hyakutake Yūji, July 7, 1950, Shimabara, Nagasaki – April 10, 2002, Kokubu, Kagoshima) was a Japanese amateur astronomer who discovered Comet C/1996 B2, also known as Comet Hyakutake on January 31, 1996, while using 25×150 binoculars. Hyakutake graduated from the Kyushu Sangyo University as a photography major and started working at a newspaper in Fukuoka. He first became interested in astronomy after seeing Comet Ikeya–Seki in 1965. He began searching for comets in 1989. In 1993, he moved to Hayato for because “the skies were much clearer there” and so he could better continue his search for comets. His first discovery was Comet C/1995 Y1, on December 26, 1995. Hyakutake discovered C/1996 B2 while looking for C/1995 Y1, a comet he had discovered a few weeks before. He died in Kokubu, Kagoshima, in 2002 at age 51 of an aneurysm which had led to internal bleeding. Asteroid 7291 Hyakutake is named after him.

8. Takao Kobayashi (b. 1961)

With an HPI of 45.90, Takao Kobayashi is the 8th most famous Japanese Astronomer. His biography has been translated into 26 different languages.

Takao Kobayashi (小林隆男, Kobayashi Takao, born 1961) is a Japanese amateur astronomer and an outstanding discoverer of minor planets who currently works at the Ōizumi Observatory. The asteroid 3500 Kobayashi is named after him.

9. Hisashi Kimura (1870 - 1943)

With an HPI of 45.62, Hisashi Kimura is the 9th most famous Japanese Astronomer. His biography has been translated into 18 different languages.

Hisashi Kimura (木村栄, Kimura Hisashi, October 4, 1870 – September 26, 1943) was a Japanese astronomer originally from Kanazawa, Ishikawa. He devoted his career to the study and measurement of variation in latitude, building upon the work of Seth Carlo Chandler, who discovered the Chandler wobble. In 1899, he became the first director of the International Latitude Observatory at Mizusawa, Japan. He won the Gold Medal of the Royal Astronomical Society in 1936. He was one of the first people to be awarded the Order of Culture when it was established in 1937. The crater Kimura on the Moon is named after him, the same for the asteroid 6233 Kimura.

10. Kaoru Ikeya (b. 1943)

With an HPI of 45.27, Kaoru Ikeya is the 10th most famous Japanese Astronomer. His biography has been translated into 17 different languages.

Kaoru Ikeya (池谷薫, Ikeya Kaoru, born 1943) is a Japanese amateur astronomer who discovered a number of comets. As a young adult, Ikeya lived near Lake Hamana and worked for a piano factory. During his employment there, he made his first discovery in 1963 with an optical telescope he built himself within his low budget. Two years later, he discovered the bright comet C/1965 S1 (Ikeya-Seki). Ikeya discovered the periodic comet 153P/Ikeya-Zhang on February 1, 2002, in Mori, Hokkaidō. The asteroid 4037 Ikeya is also named after Ikeya. On November 13, 2010, Ikeya and Shigeki Murakami co-discovered the comet P/2010 V1, now known as 332P/Ikeya-Murakami, using an optical telescope, rare in an era with access to digital imaging technology. Ikeya contributed his skill to the perfectly ground optics used in the construction of the Pentax 40 cm Cassegrain reflector telescope installed at the Singapore Science Centre Observatory in March, 1989.

People

Pantheon has 26 people classified as Japanese astronomers born between 1870 and 2000. Of these 26, 18 (69.23%) of them are still alive today. The most famous living Japanese astronomers include Tsutomu Seki, Hiroshi Kaneda, and Hiroki Kosai. The most famous deceased Japanese astronomers include Takeshi Urata, Kiyotsugu Hirayama, and Chushiro Hayashi. As of April 2024, 5 new Japanese astronomers have been added to Pantheon including Minoru Honda, Tomimaru Okuni, and Masaru Arai.