The attraction of the moon

The moon has always been irresistibly fascinating for people all over the world. So much so that it became the reference for the passage of time and a focus of scientific analysis. In the 18th century, Dresden was not only a centre of precision watchmaking but also a hub of celestial observation and lunar research – of selenography, to be precise, the systematic mapping of the moon’s surface. At the Mathematics and Physics Salon in Dresden’s Zwinger, astronomers used telescopes to create detailed maps of its visible topographic features. Today, milestones of lunar research in Saxony are on display in the scientific history collection of the museum that belongs to the Dresden State Art Collections. It reopened not long ago after renovation and is co-sponsored by A. Lange & Söhne.

Ever since the first astronomical clocks were built in the 14th century, it has been a declared objective in horology to emulate the progression of the moon as accurately as possible. The technical challenge involved in this complication is to ever more accurately approximate the lunar month of 29 days, 12 hours, 44 minutes and 3 seconds. With a moon-phase display that needs to be corrected by merely one day every 122.6 years, A. Lange & Söhne has attained a highly realistic degree of accuracy.

Since the brand’s legendary comeback in 1994, the manufacture has presented no fewer than twelve calibres with moon-phase displays. Among them are the LANGE 1 MOON PHASE based on Lange’s design icon and the 1815 RATTRAPANTE PERPETUAL CALENDAR, which had its debut this year. The coating of the lunar discs is another noteworthy aspect. Their exceptional brilliance is based on optical interference effects that reflect only the blue portions of the visible light spectrum.

The encounters between timekeeping instruments and the selenographic exhibits in the collection of the Royal Cabinet of Mathematical and Physical Instruments emphasise the strong attraction of the moon in two related disciplines: astronomy and precision watchmaking.