A moonphaseMoonphase A moonphase complication is a feature found in some watches that displays the phase of the moon as it appears in the sky. It typically includes a small disc with a representation of the moon, usually with a depiction of the lunar surface, that rotates to indicate the current phase of the moon. The disc rotates once every 29.5 days, the same period of time it takes for the moon to go through its lunar cycle. [Learn More] complication is a feature found in some watches that displays the phase of the moon as it appears in the sky. It typically includes a small disc with a representation of the moon, usually with a depiction of the lunar surface, that rotates to indicate the current phase of the moon. The disc rotates once every 29.5 days, the same period of time it takes for the moon to go through its lunar cycle.