celestial sphere
/sɛlɪˈʃɪəl ˈsɪr/ · celes·ti·al spher
noun
- An abstract sphere of infinite radius which serves as the imaginary backdrop for celestial objects, and of which the visible sky is one hemisphere. Astronomers use the celestial sphere to model the motion of stars and planets.
Did you know? The celestial sphere is a fundamental concept in astronomy, allowing scientists to visualize and predict the motion of celestial bodies across the universe.