planisphere(redirected from planispherical)
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planisphere(plan -ă-sfeer) A two-dimensional map projection centered on the northern or southern pole of the celestial sphere that shows the principal stars of the constellations, the Milky Way, etc., and is equipped with a movable overlay to indicate the stars visible at a particular time on any day of the year for a particular zone of terrestrial latitude.
the representation of a sphere on a plane in a normal (polar) stereographic projection. The planisphere was used until the 17th century to determine the times of the rising and setting of celestial bodies. It was usually a coordinate grid etched on a metal disk about whose center an alidade that facilitated calculations rotated. The planisphere fell into disuse with the introduction of special tables and nomographs.