DayNight is a screenlet that displays the areas where is night on Earth.
This screenlet shows the repartition between day and night on Earth. Refresh every 5 minutes. The world map changes during the year, so you can see the seasons too.
dayNight uses SUNRISET.C - computes Sun rise/set times, start/end of twilight, and the length of the day at any date and latitude written as DAYLEN.C, 1989-08-16.
Screenlets is the name of both a set of independently-developed widget applications and the widget engine which runs them. The engine runs primarily on X11-based compositing window managers, most notably the Compiz (under Linux) architecture.