:''There are two comets named Ikeya–Seki: C/1965 S1 (this one), and C/1967 Y1, a.k.a. 1968 I, 1967n.'' Comet Ikeya–Seki, formally designated C/1965 S1, 1965 VIII, and 1965f, was a long-period

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

discovered independently by

Kaoru Ikeya 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 bu ...

and

Tsutomu Seki is a Japanese astronomer and discoverer of minor planets and comets, born in Kōchi, Japan. Career Tsutomu Seki is the Director of the Geisei Observatory in Kōchi, and in charge of the Comet Section of the Oriental Astronomical Association. ...

. First observed as a faint telescopic object on September 18, 1965, the first calculations of its orbit suggested that on October 21, it would pass just 450,000 km above the Sun's surface, and would probably become extremely bright. Comets can defy such predictions, but Ikeya–Seki performed as expected. As it approached perihelion observers reported that it was clearly visible in the daytime sky next to the Sun. In

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, where it reached perihelion at local noon, it was seen shining at magnitude −10.Brightest comets seen since 1935
It proved to be one of the brightest comets seen in the last thousand years, and is sometimes known as the ''

Great Comet A great comet is a comet that becomes exceptionally bright. There is no official definition; often the term is attached to comets such as Halley's Comet, which during certain appearances are bright enough to be noticed by casual observers who ar ...

of 1965''. The comet was seen to break into three pieces just before its perihelion passage. The three pieces continued in almost identical orbits, and the comet re-appeared in the morning sky in late October, showing a very bright tail. By early 1966, it had faded from view as it receded into the outer

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

. Ikeya–Seki is a member of the Kreutz sungrazers, which are suggested to be fragments of a large comet which broke up in 1106.

Gallery

1965 S1.jpg, Comet Ikeya–Seki, seen from Canberra, 31 October 1965. Drawing by David Nicholls. Ikeyaseki tail 30Oct1965.jpg, Comet Ikeya–Seki, 30 October 1965. Photo by James W. Young ( TMO/JPL/NASA)

Notes

References

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External links

{{DEFAULTSORT:Ikeya-Seki, 1965 S1 Non-periodic comets Kreutz Sungrazers Destroyed comets Science and technology in Japan 19650918 Discoveries by amateur astronomers Great comets