Speedmaster Moonphase

The Omega Speedmaster Moonphase puts a lunar calendar into a chronograph whose name already has a rather literal connection to the Moon. What ties this varied family together is that contrast: elapsed-time measurement alongside the slow progress of a moon disc, expressed through different dial layouts, case sizes, and both hand-wound and automatic movements.

The Speedmaster Moonphase 3576.50 sits close to the familiar Moonwatch formula: a 42 mm case, manual-winding caliber 1866, and three chronograph registers beneath a combined date-and-moonphase display at 12. The later Speedmaster Moonphase Master Co-Axial takes a different route. In its 44.25 mm form with automatic caliber 9904, the moonphase moves to 6, while elapsed hours and minutes share the register at 3; running seconds and the pointer date occupy 9.

Dial material adds another useful distinction. Speedmaster Moonphase Aventurine versions bring a glittering, star-like surface to the astronomical display, while Speedmaster Moonphase Meteorite versions use the patterned structure of meteorite. Those names describe more than a dial color, but they do not replace the generation-specific differences in mechanics and layout.