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# parsec

(pc or psc)
a non-metric unit of distance used in astronomy. As the Earth makes its orbit around the Sun, nearby stars appear to shift their positions in relation to the background of distant stars. This shift, called the parallax of the star, is very small, less than one arcsecond even for the nearest stars. One parsec is the distance at which a star would appear to shift its position by one arcsecond during the time in which the Earth moves a distance of one astronomical unit (au) in the direction perpendicular to the direction to the star. Using this unit makes it easy to compute distances: the distance to a star, in parsecs, is simply one divided by the parallax, in arcseconds. If the parallax is 0.01 arcsecond, the distance is 100 parsecs. One parsec divided by one astronomical unit (the length of the semimajor axis of the Earth's elliptical orbit) is the trigonometric function of 0.01 arcsecond called the cotangent; from this relation we can compute that one parsec equals 206 264.8 au. This is the same as about 3.261 56 light years, 30.856 78 petameters (30.856 78 x 1012 kilometers), or 19 173 510 000 000 miles.

Dictionary of units of measurement. 2015.

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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

• 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

• Pársec — Para la revista Pársec, véase Parsec (revista) Diagrama geométrico de la definición del pársec, resultado de la ecuación Δ = r / tg π.[1] El pársec o parsec (símbolo pc) es una unidad de longitud …   Wikipedia Español