The Masterpiece Jour et Nuit is a clever design by Maurice Lacroix which uses a technique developed in the 18th century. The single hand carries moon and sun symbols, and goes round once a day. This makes for an elegant display, although it wouldn’t be popular with astronomical purists, being a good representation of the positions of the sun and moon only once a month, around the time of the full moon. There’s another example on the Design page of this site.