Celestial sphere
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In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon
Celestial globe by Jost Bürgi (1594)
Celestial pole
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The north and south celestial poles are the two points in the sky where Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear per
Over the course of an evening in the Northern Hemisphere, circumpolar stars appear to circle around the north celestial pole. Polaris (within 1° of the pole) is the nearly stationary bright star just to the right of center in this star trail photo.
The south celestial pole over the Very Large Telescope