the arc of the celestial equator measured eastward from the vernal equinox to the foot of the great circle passing through the celestial poles and a given point on the celestial sphere, expressed in degrees or hours.
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Origin of right ascension
First recorded in 1585–95
Words nearby right ascension
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020
British Dictionary definitions for right ascension
astronomy the angular distance measured eastwards along the celestial equator from the vernal equinox to the point at which the celestial equator intersects a great circle passing through the celestial pole and the heavenly object in questionSymbol: α Compare declination (def. 1)
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 right ascension
The position of a celestial object east of the vernal equinox along the celestial equator. Right ascension is measured in hours, minutes, and seconds from the vernal equinox (0 hours) to the point where a great circle drawn through the object and the north and south celestial poles intersects the celestial equator. Each hour corresponds to 15° of angular distance along the celestial equator for a total of 24 hours. See more at equatorial coordinate system.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.