The Amateur Astronomer's Introduction to the Celestial Sphere, William Millar, pp. 22, Cambridge University Press, 2006, ISBN 978-0-521-67123-1, ... The sky point straight over your head is called the zenith and its altitude is +90◦. The sky point directly below your feet (on the celestial sphere, on the other side of the Earth) is called the nadir ...
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वैज्ञानिक शब्दावली, आयोग. "zenith शब्द". csttpublication.
