In 2002, A. Lange & Söhne launched a new watch model with moon-phase display from their flagship timepiece collection LANGE 1.
The display of the LANGE 1 MOONPHASE arguably provides the most faithful emulation of synodic time. It is a display that, just like the moon itself, does not jump forward merely once per day, or twice. Instead, it is connected to the continuum of the hour wheel. The LANGE 1 MOONPHASE accurately follows the moon’s orbit – with a deviation of merely 0.002 percent.
The moon makes one complete orbit around our planet in an average of 29 days, 12 hours, 44 minutes, and 3 seconds (a synodic month). The term “average” is deliberate: because the moon’s orbit is elliptical, and because of the combined gravitational forces of the sun and the earth, the moon moves faster when it is close to the earth than when it is far away. Thus, the duration of one entire moon phase is not always the same in the course of a year.
Ordinary moon-phase displays that indicate the average (synodic) progress of the moon’s orbit generally achieve only rough approximations. Most moon-phase mechanisms use a wheel with 59 teeth, and this rounds the lunar cycle to 29.5 days. The resulting inaccuracy is 44 minutes and 3 seconds. In two and a half years, the compounded error already amounts to one whole day. Moreover, mechanisms of the type that activate the forward motion of the moon disc only once or twice a day instead of continuously have an intrinsic display error of more than 6 or 3 degrees, respectively, just before they advance.
The much more complex gear train of the LANGE 1 MOONPHASE not only drives the moon-phase display continuously and thus in the celestial rhythm of synodic time, it also minimises the mechanically inevitable display error to a smidgen: merely 1.9 seconds a day or 57 seconds for each complete lunar orbit. Mathematically speaking, this represents a deviation of only 0.002 percent. Hence, it takes 122.6 years for the error to add up to one day. However, the corrector recessed in the case between 7 and 8 o’clock allows minuscule adjustments at any time. It also readjusts the moon-phase display in the event that the watch is ever set aside for longer periods of time.
The enhanced, manually wound Calibre L901.5 movement, consisting of 398 individual parts, stands out with a host of the typical hallmarks of Lange quality, among them:
– Rigid Glashütte three-quarter plate made of cross-laminated German silver
– Twin mainspring barrels for more than three days’ power reserve
– Patented Lange outsize date
– Hand-engraved balance cock with whiplash precision index adjuster and a shock-resistant screw balance timed to 21,600 semi-oscillations per hour
– stop seconds
– 54 jewels, of which nine in screwed gold chatons
– Manually blued steel screws
– Manually bevelled and polished plate edges
– Plates and bridges damascened and solarised with Glashütte ribbing
– End stone set in a gold chaton on the separate escape wheel cock, carried by a black polished steel plate
The LANGE 1 MOONPHASE is available in three case styles and with hand-stitched crocodile straps and the sturdy Lange prong buckle: yellow gold (Ref. 109.021), pink gold (Ref. 109.032), and platinum (Ref. 109.025). Precious metal bracelets and clasps are available on request as well.
The heavy three-part cases with sapphire-crystal glasses and casebacks feature a push-piece at 10 o’clock for fast adjustments of the Lange outsize date and a recessed corrector between 7 and 8 o’clock for the moon-phase display. The ergonomic crown with the embossed Lange signature communicates perfection down to the last detail. It winds the movement and sets the time.
The neatly arranged displays on the asymmetric, tiered solid-silver dial interact with celestial harmony to tell the hours, minutes, and seconds, to indicate the power reserve, to show the outsize date in the smart twin aperture, and now to faithfully track the orbit of the moon which is framed by the seconds scale. The LANGE 1 MOONPHASE salutes the night with its luminous hour, minute, and power-reserve hands as well as its glowing hour markers.
In this particular case, the asymmetric dial architecture designed in 1990 for the first Lange timepiece of the revival has proved to be quite providential: the position of the moon-phase display on the dial relative to the hour and minute scale is congruent with the position of the moon relative to the earth.