The angular distance of a celestial object eastward along the celestial equator from the vernal equinox point, measured in hours, minutes, and seconds. It's the celestial equivalent of longitude on Earth.
From Latin 'ascensio recta' meaning 'straight rising,' referring to the arc that rises perpendicularly from the horizon at the celestial equator. The term was established in medieval astronomy to distinguish it from 'oblique ascension' used in different coordinate systems.
Right ascension is measured in time units (24 hours total) rather than degrees because it's tied to Earth's rotation - as our planet spins, objects with the same right ascension cross your meridian exactly 24 hours apart! It's like cosmic longitude that ticks like a clock.
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