The Equatorial Coordinate System is a celestial coordinate system used to specify the positions of objects in the sky. It is based on the projection of the Earth's equator and poles onto the celestial sphere, allowing astronomers to locate stars and other celestial bodies. The two main coordinates are right ascension (similar to longitude) and declination (similar to latitude). Right ascension is measured in hours, minutes, and seconds, while declination is measured in degrees. This system is particularly useful for locating objects like stars, planets, and galaxies as it remains fixed relative to the celestial sphere, making it easier to track their movements over time.