Three of A. Lange & Söhne’s most spectacular models channel one of Mother Nature’s most fascinating extravaganzas, the Northern Lights seen in the Arctic sky above Iceland.
The trio of luminous timepieces from the luxury watch manufacture include the GRAND LANGE 1 MOON PHASE “Lumen”, which was first presented in January 2016, as well as the ZEITWERK “Luminous” and the GRAND LANGE 1 “Lumen”.
Each model possesses a semi-transparent sapphire-crystal dial, with a light permeable coating which allows the numerals to absorb a sufficient amount of light energy to uniformly glow in the dark for several hours.
Watches with luminous displays need a light source that charges the luminous compound applied to the display elements and allows them to glow.
On account of the semi-transparent black-tinted dial and an ingenious mechanism, the displays of the GRAND LANGE 1MOON PHASE “Lumen” and of the other swiss watch A. Lange & Söhne “Lumen” models can be permanently charged with light energy.
The dial of the GRAND LANGE 1 MOON PHASE “Lumen” is made of blackened silver with generous apertures and a semi-transparent black tinted sapphire-crystal glass wafer. The special coating applied to the glass, blocks most of the visible light but not the UV spectra that “charge” the luminous pigments on the outsize date mechanism and cause them to glow in the dark.
The tens cross is coated with a white luminous compound and printed with black numerals. The units disc, also featuring black numerals, is made of transparent glass and rotates in front of the luminous background of the date aperture.
At the same time, the lunar disc is made of glass. Its glass surface is firstly coated with a patented process, then 1,164 stars and the moon are cut out with a laser beam. The luminous compound behind the lunar disc is what makes the moon and the stars shine.
The large moon-phase display occupies a prominent position on the main dial. Once properly set, it only needs to be corrected by one day every 122.6 years.
Why the northern lights are green?
The rare natural phenomenon can be observed in the polar region merely during a few days between September and March. Complex physical processes create the polychrome auroras in the upper strata of the earth’s atmosphere.
The green light, to which our eyes are particularly receptive, occurs at an altitude of about 100 kilometres. Here, oxygen atoms collide with the electrically charged particles of the solar winds. These collisions emit light with a wavelength of 557.7 nanometres, which the human eye perceives as green.