Glossary

The moon phase complication displays the complete cycle of the moon through a window or aperture on the watch dial. This window contains a small disc that represents the phases of the moon and is moved by a specific mechanism to indicate these phases. The display can be adjusted manually or automatically, depending on the design and internal mechanics of the watch.

The moon phase cycle consists of four phases: new moon, first quarter, full moon, and last quarter. This complication employs a precise mechanism to move the disc in a way that reflects the actual movement of the moon in the sky. Typically, the display is accompanied by other indicators, such as the basic timekeeping functions of hours, minutes, and seconds.