parsecs

parsec

[pahr-sek]
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.

Origin:
1910–15; par(allax) + sec(ond)2

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World English Dictionary
parsec (ˈpɑːˌsɛk)
 
n
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 × 1016 m or 3.262 light years
 
[C20: from parallax + second²]

Collins English Dictionary - Complete & Unabridged 10th Edition
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Etymonline
Word Origin & History

parsec
1913, from par(allax) sec(ond). It is the distance at which an object has parallax (viewed from Earth) of one second of arc, or about 3.26 light years.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
parsec  [%PREMIUM_LINK%]     (pär'sěk')  Pronunciation Key 
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.

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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Abbreviations & Acronyms
parsec
parallax second
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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