Skip to definition.
Get the FREE one-click dictionary software for Windows or the iPhone/iPad and Android apps

Noun: right ascension  rIt u'sen-shun
  1. (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
    "one hour of right ascension equals fifteen degrees";
    - RA, celestial longitude

Derived forms: right ascensions

Type of: angular distance

Encyclopedia: Right ascension