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parsec

[ pahr-sek ]
/ ˈpɑrˌsɛk /
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noun Astronomy.

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.

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Origin of parsec

First recorded in 1910–15; par(allax) + sec(ond)2
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for parsec

parsec
/ (ˈpɑːˌsɛk) /

noun

a unit of astronomical distance equal to the distance from earth at which stellar parallax would be 1 second of arc; equivalent to 3.0857 × 10 16 m or 3.262 light years

Word Origin for parsec

C20: from parallax + second ²
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for parsec

parsec
[ pärsĕk′ ]

A unit of astronomical length equal to 3.26 light-years. It is based on the distance from Earth at which a star would have a parallax of one second of arc. Its metric equivalent is about 30.8 trillion km (19.1 trillion mi). It is used in measuring distances in interstellar and intergalactic space. The closest star to Earth, Alpha Centauri, is about 1.3 parsecs away. Compare astronomical unit light-year.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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