The position of the Sun in the sky is a function of both the time and the geographic location of observation on Earth's surface. As Earth orbits the Sun over the course of a year, the Sun appears to move with respect to the fixed stars on the celestial sphere, along a circular path called the ecliptic.
Earth's rotation about its axis causes diurnal motion, so that the Sun appears to move across the sky in a Sun path that depends on the observer's geographic latitude. The time when the Sun transits the observer's meridian depends on the geographic longitude.
To find the Sun's position for a given location at a given time, one may therefore proceed in three steps as follows:[1][2]
This calculation is useful in astronomy, navigation, surveying, meteorology, climatology, solar energy, and sundial design.
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