Right ascension

Right ascension (abbrev. RA; symbol α) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.
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Noun
1. (astronomy) the angular distance eastward along the celestial equator from the vernal equinox to the intersection of the hour circle that passes through the body; expressed in hours and minutes and second; used with declination to specify positions on the celestial sphere; "one hour of right ascension equals fifteen degrees"
(synonym) RA, celestial longitude
(hypernym) angular distance
(classification) astronomy, uranology
2. an arc of the celestial equator eastward from the vernal equinox
(hypernym) celestial equator, equinoctial circle, equinoctial line, equinoctial

One of the ordinates used to reference objects on the celestial sphere. It is the equivalent to a longitude reference on the Earth. There are 24 hours of right ascension within 360 degrees, so one hour is equivalent to 15 degrees. Together with declination, it represents the most commonly used co-ordinate system in modern astronomy. Zero hours is the point at which the ecliptic crosses the projection of the Earth's equator onto the celestial sphere.

ASCENSIONE RETTA [ASTRONOMIA]

Eng: right ascension
Urdu: (فَلکِیات) مَطلَعِ اِستَوائی ۔