# parsec

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parsec
/pahr"sek'/, n. Astron.
a unit of distance equal to that required to cause a heliocentric parallax of one second of an arc, equivalent to 206,265 times the distance from the earth to the sun, or 3.26 light-years.
[1910-15; PAR(ALLAX) + SEC(OND)2]

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Unit of measure used by astronomers to express distances to stars and galaxies.

It is the distance at which the radius of Earth's orbit would subtend an angle of one second of arc, so an object one parsec away would have a parallax of one second. An object's distance in parsecs is the reciprocal of its parallax in seconds of arc. For example, Alpha Centauri, with a parallax of 0.76 second, is 1.33 parsecs from the Sun and Earth. One parsec equals 3.26 light-years, or 19.2 trillion mi (30.9 trillion km).

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▪ unit of measurement
unit for expressing distances to stars and galaxies, used by professional astronomers. It represents the distance at which the radius of the Earth's orbit subtends an angle of one second of arc; thus a star at a distance of one parsec would have a parallax of one second, and the distance of an object in parsecs is the reciprocal of its parallax in seconds of arc. For example, the nearest triple-star system, Alpha Centauri A and B and Proxima Centauri, has a parallax of 0.747 second of arc; hence, its distance from the Sun and the Earth is 1.34 parsec. One parsec equals 3.26 light-years (light-year), which is equivalent to 3.09 × 1013 km (1.92 × 1013 miles). In the Milky Way Galaxy, wherein the Earth is located, distances to remote stars are measured in terms of kiloparsecs (1 kiloparsec = 1,000 parsecs). The Sun is at a distance of 8.5 kiloparsecs from the centre of the Milky Way system. When dealing with other galaxies or clusters of galaxies, the convenient unit is the megaparsec (1 megaparsec = 1,000,000 parsecs). The distance to the Andromeda Galaxy (Messier 31) is about 0.7 megaparsec. Some galaxies and quasars have likely distances on the order of about 4,000 megaparsecs, or 13,000,000,000 light-years.

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Universalium. 2010.

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• parsec — [ parsɛk ] n. m. • 1923; de par(allaxe) et seconde ♦ Métrol., astron. Unité de mesure de longueur (symb. pc) utilisée en astronomie, valant 3,26 années lumière. ● parsec nom masculin (de parallaxe, et seconde) Unité de distance (symbole pc)… …   Encyclopédie Universelle

• parsec — PARSÉC, parseci, s.m. Unitate de lungime folosită în astronomie, egală cu distanţa parcursă de lumină în 3,26 ani. – Din fr. parsec. Trimis de valeriu, 03.02.2004. Sursa: DEX 98 ﻿ parséc s. m., pl. parséci Trimis de siveco, 10.08.2004. Sursa:… …   Dicționar Român

• parsec — s. m. [Astronomia] Unidade astronômica de distância equivalente à distância de uma estrela cuja paralaxe anual seria de um segundo. (O parsec equivale a 3,26 anos luz, ou seja 3,08.1013 quilômetros.)   ‣ Etimologia: inglês parsec, de par[allax] + …   Dicionário da Língua Portuguesa

• parsec — o pársec (Del ingl. parsec, acrón. de parallax second, segundo de paralaje). m. Astr. Unidad astronómica de longitud, igual a la distancia de un cuerpo celeste desde el que se viera el semieje mayor de la órbita terrestre con un ángulo de un… …   Diccionario de la lengua española

• pársec — parsec o pársec (Del ingl. parsec, acrón. de parallax second, segundo de paralaje). m. Astr. Unidad astronómica de longitud, igual a la distancia de un cuerpo celeste desde el que se viera el semieje mayor de la órbita terrestre con un ángulo de… …   Diccionario de la lengua española

• parsec — par sec (p[aum]r s[e^]k), n. [From parallax second. See {parallax second} and {annual parallax}, under {parallax}.] (Astron.) A unit of length used in describing astronomical distances, equal to 3.26 light years, or 3.086 x 1013 km. Abbreviated… …   The Collaborative International Dictionary of English

• parsec — (n.) 1913, from first elements of parallax second. It is the distance at which an object has parallax (viewed from Earth) of one second of arc, or about 3.26 light years …   Etymology dictionary

• parsec — (izg. parsȅk) m DEFINICIJA astron. posebna jedinica za daljinu u astronomiji; udaljenost zvijezde od Sunca pri kojoj zvjezdana paralaksa iznosi 1 ; znak pc ETIMOLOGIJA krat., engl. par (allax): paralaksa + sec (ond): sekunda …   Hrvatski jezični portal

• parsec — ► NOUN ▪ a unit of astronomical distance equal to about 3.25 light years, corresponding to the distance at which the radius of the earth s orbit subtends an angle of one second of arc. ORIGIN blend of PARALLAX(Cf. ↑parallax) and SECOND(Cf.… …   English terms dictionary

• parsec — [pär′sek΄] n. [ PAR(ALLAX) + SEC(OND)] a unit of distance, usually used to measure the distance to a star, equal to 206,265 astronomical units (3.0857 x 1013 kilometers or 1.92 x 1013 miles or 3.2616 light years): it is the distance at which an… …   English World dictionary

• Parsec — For other uses, see Parsec (disambiguation). 1 parsec = SI units 30.857×10^12 km 30.857×10^15 m Astronomical units 206.26× …   Wikipedia