celestial sphere

noun

1. the imaginary spherical shell formed by the sky, usually represented as an infinite sphere, the center of which is a given observer's position.

celestial sphere

noun

1. an imaginary sphere of infinitely large radius enclosing the universe so that all celestial bodies appear to be projected onto its surface

celestial sphere

1. An imaginary sphere with Earth at its center. The stars, planets, Sun, Moon, and other celestial bodies appear to be located on this sphere, and the sphere appears to rotate around the Earth's extended axis once every 24 hours, carrying the celestial bodies with it overhead and giving them their diurnal motions. The celestial sphere is essentially a spherical map of the sky that provides the basis for the coordinate systems used in celestial navigation and in specifying the positions and motions of celestial objects.
2. See more at altazimuth coordinate system

Word History and Origins

Origin of celestial sphere¹

First recorded in 1875–80

Example Sentences

The fifth creation is the celestial Sphere, where for the first time we have motion in its revolutions.

From Project Gutenberg

When a star reaches the meridian in its course across the celestial sphere it is said to culminate or reach its culmination.

From Project Gutenberg

A star rising due east would traverse this great circle of the celestial sphere and set due west.

From Project Gutenberg

In Fig. 5, the outer arc again represents the path of the zodiac on the celestial sphere.

From Project Gutenberg

In Fig. 4, the outer circle represents the path of the zodiac on the celestial sphere.

From Project Gutenberg