Looking at the figure above, the local vertical line in P crosses the parallel rays coming from the celestial body, and then the ZD angle as seen from P is also the angular distance of P from S respect to the center of the Earth O. Since the celestial bodies are so far away from the Earth, rays coming from them are practically parallel. From our position in P we will see the light of the celestial body coming from the same exact direction, but at a certain angle from our Zenith this angle is named Zenith distance of the celestial body and indicated as ZD. An observer located in S will see the celestial body over its head, that is at its Zenith. How this can be made is the subject of this article.īe S the position on the Earth of a certain celestial body at a given day and time, and be P our position. The vice-versa is also possible too: given day, time and the position of the celestial bodies in the sky, it is possible to determine our own position on the Earth. So, given day, time and location on the Earth, the position on the sky of any of these celestial bodies can be determined. The positions of these of all main celestial bodies (Sun, Moon, stars and planets) are calculated and published year by year for the needs of the celestial navigation. The position of the celestial bodies in the sky can be predicted with extreme accuracy by calculation. Our purpose is merely educational and our self-made tools very basic, but despite that we will determine our position with an accuracy of few tens of Km. In this article we show how it is possible to determine our own position on the Earth by using simple tools available at home and some calculations.
Fixed Bennett's formula for refraction correction.
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