Given the date, time, latitude, longitude, and time zone of a location, this page
calculates the position of the sun. North latitude, west longitude
and US time zones are all positive numbers. Latitude, longitude, and all
results (except radius) are in decimal degrees, including right ascension and the
equation of time.
View the source code to this page to see the underlying formulas used.
They come from Jean Meeus' excellent Astronomical Algorithms, 2nd edition,
published by Willmann-Bell of Virginia.