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, with each hour representing 15 degrees of angle. This measurement helps astronomers locate stars, planets, and other celestial bodies. Right Ascension is typically paired with Declination, which measures the angle north or south of the celestial equator, allowing for a complete system to pinpoint objects in the night sky.