Which two coordinates are used to identify celestial bodies on the Celestial Sphere?

The two coordinates used to identify celestial bodies on the Celestial Sphere are declination and Greenwich hour angle.

Declination is analogous to latitude on Earth; it measures the angle of a celestial object north or south of the celestial equator. It helps to pinpoint the object's position in the sky, indicating its height above or below the equatorial plane.

Greenwich hour angle, on the other hand, is analogous to longitude and represents the time since the object last crossed the Greenwich meridian. It is measured in time units and indicates how far east or west an object is located in relation to the prime meridian of the celestial sphere.

Together, these two coordinates allow astronomers and navigators to locate celestial bodies accurately at any given time, making them essential for celestial navigation and the use of star charts.