Zytglogge, Bern ( Schweiz ) Royalty-Free Stock Photography

The dial of the Zytglogge's astronomical clock is built in the form of an astrolabe. It is backed by a stereographically projected planisphere divided into three zones: the black night sky, the deep blue zone of dawn and the light blue day sky. The skies are crisscrossed with the golden lines of the horizon, dawn, the tropics and the temporal hours, which divide the time of daylight into twelve hours whose length varies with the time of year.