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Relationship between zenith, nadir and horizon
Trees that have just grown point to the zenith in the sky.
At the sub-solar point (here on September 17th at noon in Singapore ) the sun is at its zenith; the shadow is vertical.

The zenith is the vertical direction of a location that is extended upwards . The opposite direction is called nadir ("foot point"). This axis defines the horizon plane as its normal . Together with the celestial poles , the zenith is the basis for astronomical coordinate systems .

The name comes from the Arabic سمت الرأس / including ar-raʾs  / 'direction of the head'. Spelling mistakes and incorrect readings resulted in medieval texts from including the spelling cemt or zemt and from this cenit or zenit .

The Geodesy considers the vertical deflection between the zenith and the isolated ellipsoidal Zenit normal referred to the reference ellipsoid .

See also

Individual evidence

  1. Wolfgang Torge : Geodesy. De Gruyter, 2003, ISBN 3-11-017545-2 , limited preview in the Google book search.
  2. Collins English Dictionary - Complete & Unabridged. 10th edition, quoted from Dictionary.com .
  3. Wolfgang Torge: Geodesy. De Gruyter, 2003, ISBN 3-11-017545-2 , p. 90 .

Web links

Wiktionary: Zenit  - explanations of meanings, word origins, synonyms, translations