ActiveEarth is a world time clock with a day/night merge of NASA's Visible Earth satellite images in flat maps or a globe, with a row of user-definable clocks along the bottom. These clocks are scalable, ticking, analog clocks that come in several styles with custom settings. Each clock is set to a city of your choice. The program has accurate time zone data for more than 500, major world cities and you can add your own.