Right ascension Meaning, Definition & Usage

  1. noun (astronomy) the equatorial coordinate specifying the angle, measured eastward along the celestial equator, from the vernal equinox to the intersection of the hour circle that passes through an object in the sky; usually expressed in hours and minutes and seconds; used with declination to specify positions on the celestial sphere
    celestial longitude; RA.
    • one hour of right ascension equals fifteen degrees

WordNet

Definitions
  1. (Astron.), that degree of the equinoctial, counted from the beginning of Aries, which rises with a star, or other celestial body, in a right sphere; or the arc of the equator intercepted between the first point of Aries and that point of the equator that comes to the meridian with the star; expressed either in degrees or in time.
Definitions
  1. . See under Ascension.

Webster 1913