<P> This calculation is useful in astronomy, navigation, surveying, meteorology, climatology, solar energy, and for designing sundials . </P> <P> These equations, from the Astronomical Almanac, can be used to calculate the apparent coordinates of the Sun, mean equinox and ecliptic of date, to a precision of about 0 °. 01 (36"), for dates between 1950 and 2050 . </P> <P> Start by calculating n, the number of days (positive or negative) since Greenwich noon, Terrestrial Time, on 1 January 2000 (J2000. 0). If you know the Julian date for your desired time then </P> <Dl> <Dd> n = J D − 2451545.0 (\ displaystyle n = \ mathrm (JD) - 2451545.0) </Dd> </Dl>

How and why do the suns celestial coordinates change over the course of each year