Right ascension is a coordinate used in astronomy to measure the position of celestial objects in the sky. It is similar to longitude on Earth but is measured in hours, minutes, and seconds. The celestial sphere is divided into 24 hours of right ascension, with 0 hours corresponding to the position of the vernal equinox. Right ascension helps astronomers locate stars, planets, and other celestial bodies. When combined with declination, which measures the angle above or below the celestial equator, right ascension allows for precise navigation and observation of objects in the night sky.