The World's Most Accurate Moon Phase Watch

The moon phase display is one of the most fascinating complications in watchmaking. It shows the current moon phase on the dial, so you won’t miss a full moon even if clouds block it. Since IWC launched the perpetual calendar 40 years ago, it has been constantly improving the accuracy of the moon phase display. In 1985, the Da Vinci Perpetual Calendar Chronograph (Model: IW3750) designed by former IWC chief watchmaker Kurt Klaus had a moon phase accuracy of 122 years, and the first Portuguese series perpetual calendar watch (Model: IW5021) launched in 2003 had a moon phase accuracy of 577.5 years. To this day, the new Portuguese series perpetual calendar watch has once again broken through the limit and has been officially recognized by the Guinness World Records (GWR) as the "world's most accurate moon phase display watch" with a theoretical accuracy of more than 45 million years. Guinness World Records, founded in 1955, has developed into the world's most well-known record certification authority, recording and verifying various human and natural records. Before being awarded, each record goes through a rigorous review and verification process to ensure it meets Guinness' stringent standards.

In the moon phase display, a reduction gear system is placed between the base movement and the moon phase disc. This gear system reduces the length of a calendar month to the length of a lunar cycle, which is 29 days, 12 hours, 44 minutes and 2.88 seconds. The key to the display accuracy lies in the number of gears, ratios and teeth used. For the Portugieser Eternal Calendar, IWC engineers designed a new reduction gear system using three intermediate gears, two more than the previous module with an accuracy of 577.5 years.

In order to develop a solution that is robust enough and can operate reliably over an extremely long period of time, IWC's engineers defined key parameters such as the minimum and maximum number of teeth for each gear, for which they developed a special computational simulation program and calculated nearly 23 trillion different gear tooth combinations. In an iterative process, the engineers gradually found the best gear combination for this specific requirement. Assuming that the duration of the lunar phase cycle is constant at 29 days, 12 hours, 44 minutes and 2.88 seconds, IWC's newly designed moon phase profit and loss display will theoretically deviate from the lunar orbit by only one day after 45,361,055 years. Best cheap watches online, discover our affordable replica IWC Portugieser watches collection. Wide range of luxury watches brands.