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The following is the IAU's list of periodic comets that have a number designation. Logo of the IAU The International Astronomical Union (French: Union astronomique internationale) unites national astronomical societies from around the world. ...
A comet is a small body in the solar system that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail — both primarily from the effects of solar radiation upon the comets nucleus, which itself is a minor body composed of rock, dust...
Periodic comets have orbital periods of less than 200 years or have been observed during more than a single perihelion passage (e.g. 153P/Ikeya-Zhang). They receive a permanent number prefix only after the second perihelion passage, which is why there are a number of unnumbered periodic comets, such as P/1990 V1 (Comet Shoemaker-Levy 1). For a list of unnumbered periodic comets see Cometography.com. This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...
Comet Ikeya-Zhang (officially designated 153P/Ikeya-Zhang) is a comet discovered independently by two astronomers from Japan and China in 2002. ...
In nearly all cases, comets are named after their discoverer(s), but in a few cases such as 2P/Encke and 27P/Crommelin they were named for a person who calculated their orbits (the orbit computers). The orbits of periodic comets are especially tricky to calculate because of all the possible perturbations from every planet, and in the days before electronic computers some people dedicated their entire careers to this. Even so, quite a few comets were lost because their orbits are also affected by non-gravitational effects such as the release of gas and other material that forms the comet's coma and tail. Comet Encke (officially designated 2P/Encke) is a periodic comet, named after Johann Franz Encke, who through laborious study of its orbit and many calculations was able to link multiple observations in the years 1786, 1795, 1805 and 1818 to the same object. ...
The comet Ikeya-Zhang exhibiting a bright, condensed coma (march 2002) In astronomy, the nebulous envelope around the nucleus of a comet is called its coma (from the Latin word for hair). It is formed when the comet passes close to the sun on its highly elliptical orbit; as the...
Periodic comets sometimes bear the same name repeatedly (e.g. the nine Shoemaker-Levy comets or the twenty-three NEAT comets); the IAU system distinguishes between them either through the number prefix (as in the table below) or by the full designation (e.g. P/1990 V1 and P/1991 V1 are both "Comet Shoemaker-Levy"). In the literature, an informal numbering system is applied to periodic comets (skipping the non-periodic ones), thus P/1990 V1 and P/1991 V1 are known as Comet Shoemaker-Levy 1 and Comet Shoemaker-Levy 6, respectively. Non-periodic Shoemaker-Levy comets are interleaved in this sequence: C/1991 B1 between 2 and 3, C/1991 T2 between 5 and 6, C/1993 K1 and C/1994 E2 after Shoemaker-Levy 9. Gaps appear in the table below (e.g. Comet Barnard 1) when periodic comets are destroyed (they disintegrate, hit a planet like Jupiter, or are ejected from the solar system); thus Comet Barnard 1 is D/1884 O1, last seen on November 20, 1884. Near Earth Asteroid Tracking (NEAT) is a program run by NASA and Jet Propulsion Laboratory to discover near-Earth objects. ...
November 20 is the 324th day of the year (325th in leap years) in the Gregorian Calendar. ...
1884 (MDCCCLXXXIV) is a leap year starting on Tuesday (click on link to calendar) of the Gregorian calendar (or a leap year starting on Thursday of the 12-day-slower Julian calendar). ...
In comet nomenclature, the letter before the "/" is either "C" (a non-periodic comet), "P" (a periodic comet), "D" (a comet which has been lost or has disintegrated), or "X" (a comet for which no reliable orbit could be calculated —usually historical comets). In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. ...
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