What is celestial sphere?

Celestial Sphere

In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the observer. All objects in the observer's sky can be thought of as projected upon the inside surface of the celestial sphere, as if it were the underside of a dome or a hemispherical screen. The celestial sphere is a practical tool for spherical astronomy, allowing observers to plot positions of objects in the sky when their distances are unknown or unimportant.

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Famous quotes containing the words celestial and/or sphere:

    Happy those early days! when I
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    Before I understood this place
    Appointed for my second race,
    Or taught my soul to fancy aught
    But a white, celestial thought;
    Henry Vaughan (1622–1695)

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