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The word comet derives from the Old English cometa from the Latin comēta or comētēs. That, in turn, is a romanization of the Greek κομήτης 'wearing long hair', and the Oxford English Dictionary notes that the term (ἀστὴρ) κομήτης already meant 'long-haired star, comet' in Greek.
Periodic comets (also known as short-period comets) are comets with orbital periods of less than 200 years or that have been observed during more than a single perihelion passage [1] (e.g. 153P/Ikeya–Zhang). "Periodic comet" is also sometimes used to mean any comet with a periodic orbit, even if greater than 200 years.
A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.
Periodic comets usually have elongated elliptical orbits, and usually return to the vicinity of the Sun after a number of decades. The official names of non-periodic comets begin with a "C"; the names of periodic comets begin with "P" or a number followed by "P". Comets that have been lost or disappeared have names with a "D". Comets whose ...
These comets come from the Kuiper belt and scattered disk, beyond the orbit of Pluto, with possible origins in the Oort cloud for many. For comets with an orbital period of over 1000 years (semi-major axis greater than ~100 AU), see the List of near-parabolic comets.
An artist's concept of a planetary system. A planetary system is a set of gravitationally bound non-stellar bodies in or out of orbit around a star or star system.Generally speaking, systems with one or more planets constitute a planetary system, although such systems may also consist of bodies such as dwarf planets, asteroids, natural satellites, meteoroids, comets, planetesimals [1] [2] and ...
In an attempt to link the 1843 and 1880 comets to the comet in 1106 and 371 BC, Kreutz measured the fragments of the 1882 comet and determined that it was likely a fragment of the 1106 comet. He then designated that all sungrazing comets with similar orbital characteristics as these few comets would be part of the Kreutz Group. [4]
As the comet warms, parts of it sublimate; [1] this gives a comet a diffuse appearance when viewed through telescopes and distinguishes it from stars. The word coma comes from the Greek κόμη (kómē), which means "hair" and is the origin of the word comet itself. [2] [3] The coma is generally made of ice and comet dust. [1]