[n] ancient hawk-headed Egyptian sun god; a universal creator
[n] (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"
[n] an intensely radioactive metallic element that occurs in minute amounts in uranium ores