Seems like every couple years I end up writing a program to calculate planetary orbits. This time I chose to use Haskell.
Celestial bodies and their trajectories across the skies have always fascinated people. Sun, moon and stars follow very predictable paths and one can predict certain events with great accuracy. Many religious events have been tied to timing of some special event (Easter for example, Sunday after first full moon after vernal equinox). So no wonder people have long kept track of these and tried to predict when things are about to happen.