the celestial sphere

The celestial sphere is an imaginary sphere that surrounds the Earth, onto which all celestial objects like stars, planets, and the sun are projected. It helps astronomers map the positions and movements of these objects in the sky. The Earth is at the center of this sphere, and its surface serves as a reference point. Locations on the celestial sphere are defined by coordinates similar to latitude and longitude on Earth, called right ascension and declination. This concept aids in understanding celestial navigation and the apparent motion of the sky as viewed from Earth.