celestial sphere

American  

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.

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celestial sphere British  

noun

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

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celestial sphere Scientific  

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 ecliptic coordinate system equatorial coordinate system

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Etymology

Origin of celestial sphere

First recorded in 1875–80

Example Sentences

Believing that spacetime is a real, physical entity is no more defensible than believing in the old idea of a celestial sphere.

From Science Daily

But from a terrestrial perspective, the celestial sphere appears essentially unchanging.

From Scientific American

This pairing hums with a soft energy, attuned perhaps to the same celestial spheres that Gouverneur hoped to crack open.

From Washington Post

But there’s no need to be perfectly versed in every detail of the celestial sphere.

From New York Times

In his only surviving work, Hipparchus criticized earlier astronomical writers for not caring about numerical accuracy in their visions of orbits and celestial spheres.

From Scientific American