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thumb|upright=1.25|right|Diagram showing the relationship between the zenith, the nadir, and different types of [[horizon]] The zenith (, ) is the imaginary point on the celestial sphere directly "above" a particular location. "Above" means in the vertical direction (plumb line) opposite to the gravity direction at that location (nadir). The zenith is the "highest" point on the celestial sphere. The direction opposite of the zenith is the nadir.
AI overview
The zenith is an imaginary point on the celestial sphere that lies directly above any particular location on Earth, determined by the direction opposite to gravity at that spot. It matters because it provides a reference point for describing the positions of stars and celestial objects in the sky, making it a fundamental concept in astronomy and navigation.
AI-generated from the Wikipedia summary — may contain errors.