The A. Lange & Söhne Richard Lange Perpetual Calendar “Terraluna”

WATCHES OF SWITZERLAND is pleased to announce the arrival of a very special A. Lange & Söhne timepiece.

After a four-year wait, WATCHES OF SWITZERLAND is pleased to announce the arrival of a very special A. Lange & Söhne timepiece. The RICHARD LANGE PERPETUAL CALENDAR “Terraluna”. Capable of accurately reflecting the lunar cycle for more than a thousand years before deviating by a single day, this incredible mechanical masterpiece is like your own personal planetarium. A miniaturised astronomical ballet flawlessly reproduces the waxing and waning moon, as well as the constellation formed by the earth, moon and sun.

WATCHES OF SWITZERLAND has the privilege of bringing to market the first, and likely only, RICHARD LANGE PERPETUAL CALENDAR “Terraluna” in Australia. This unique piece will be available in an 18k white gold case. Featuring a solid silver dial with blued steel hands. This is an exciting event, and the only one of its kind in the country. Read on to find out why this A. Lange & Söhne masterpiece is so special.

A Masterpiece from back-to-front

The RICHARD LANGE PERPETUAL CALENDAR “Terraluna” made its debut at the SIHH in 2014 and was an instant hit. It represents the next step in innovation and technical mastery that has characterised the modern A. Lange & Söhne era. It is the pinnacle of Saxon watchmaking artistry. In its debut year, it was awarded the “Calendar Watch Prize” (by an international jury) at the Grand Prix d’Horlogerie, Geneva. That same year it was named “Watch of the Year” at the Salón Internacional Alta Relojería (SIAR), Mexico City. And received first prize in the Innovation category at the first GQ Time Awards, Munich.

The RICHARD LANGE PERPETUAL CALENDAR “Terraluna” is a manually wound, science-inspired, mechanical wristwatch. With a focus on enhanced precision. The case measures 45.5mm, with a thickness of 16.5mm, and is equally seductive on both sides. It features a patented orbital moon-phase display, regulator dial, perpetual calendar with Lange outsized date, a day/ night indicator for the northern hemisphere, power reserve of 14 days, and a constant force escapement. Winding and time setting is actioned via the crown. A push piece at 2 o’clock advances all calendar displays. Recessed push pieces allow for separate correction of the day of the week, month and moon phase. This is the first A. Lange & Söhne to integrate a moon phase on the movement side.

Blue moons accounted for

The Moon is Earth’s only permanent natural satellite. It takes 27.3 days (its sidereal period) to complete its orbit around Earth. However, because the earth is also travelling around the sun, it takes slightly longer for the same moon phase to appear to the earth. 29 days, 12 hours, 44 minutes and 3 seconds to be exact. The synodic period, as it is known, is therefore the one watchmakers focus on representing as the observed lunar cycle. For simplicity’s sake, most round down the new moon period to 29.5 days.

The regular waxing and waning phases of the moon make for a very convenient timekeeper. Many of the oldest calendar systems are based on the lunar cycle. The most commonly used Gregorian calendar, however, is a solar calendar (though it originally evolved out of a lunar calendar). As such a ‘discrepancy’ occurs on average every two and a half years. Where a second full moon falls in the same calendar month. This rare phenomenon is referred to as a ‘blue moon’. Most mechanical moon phases need to be corrected by one day ‘once in a blue moon’ because of the rounding. The RICHARD LANGE PERPETUAL CALENDAR “Terraluna” is different. It’s patented orbital moon-phase display reproduces the synodic lunar orbit precisely.

The “Terraluna” patented orbital moon-phase display


A. Lange & Söhne are experts when it comes to moon-phase displays. Since 1994, they have created no less than 15 manufacture calibres incorporating the complication. In nearly all, a correction by one day is only required after 122.6 years. (50 times more accurate than conventional displays). However, the RICHARD LANGE PERPETUAL CALENDAR “Terraluna” sets the benchmark far beyond this. It’s so precise that it takes 1,058 years before the display needs to be corrected by one day.

The orbital moon-phase display is integrated into the watch movement itself. It consists of three discs, made of 18k solid white gold, that work in unison. A deep blue celestial disc represents space. The patented blue coating is laser-inscribed with precisely 2,116 stars. An earth disc (depicting the northern hemisphere) sits at its centre. Rotating on its axis every 24 hours. And a lunar disc located beneath the celestial disc is visible through a round aperture. This round aperture represents the position of the moon in relation to the earth. And its constellation relative to the sun – whose position is defined by the balance.

The star-studded celestial disc turns anticlockwise around the earth disc. And the round aperture within it thus mimics the orbit of the moon. The lunar disc follows the orbit path from below. Turning independently to display the waxing and waning moon face (as seen from the northern hemisphere). A planetary wheel train assures that the moon phase is always correctly represented. In slightly more than 29.5 days, the moon orbits the earth once. (From new moon, waxing moon, full moon and waning moon, before repeating.)

By the position of the balance (as the sun), one can discern the arbitrary line cast across the earth, separating day from night. This is aided by a 24-hour indication around the circumference of the display. Dawn, noon, dusk and midnight can all be observed for the different countries depicted on the rotating earth disc. (Tracing a line from the North Pole through a city on the map to the circumference indexes will give you an approximate time for that city.) If you can manage to tear your attention away from the rear of the wristwatch, the science-driven complexity continues on the front.

A Regulator dial with perpetual calendar accurate to 2100

The dial layout of the RICHARD LANGE PERPETUAL CALENDAR “Terraluna” is known as a ‘regulator’. Inspired by an 1807 regulator clock by Johann Heinrich Seyffert. (The piece resides in the collection of the Royal Cabinet of Mathematical and Physical Instruments, in Dresden. Seyffert’s work was significant in transforming Dresden into the precision horology hub of the early 19th century. To which original company founder Ferdinand A. Lange was born into.) The regulator format was of great advantage. It provided accurate readings of the minutes and seconds. (Watch manufacturers used regulators to synchronise new timepieces.) The technology was employed in precision pocket watches, timekeeping services and observatories.

The RICHARD LANGE PERPETUAL CALENDAR “Terraluna” dial features three eccentrically positioned circles. The dominant of these is the sweep minute counter. Hours are indicated at the lower right (with Roman numerals). And the seconds at the lower left (with stop seconds available). The asymmetry of the regulators and tempered blued hands is perfectly balanced. Making for a reader-friendly dial. (This is important given the amount of information being conveyed.)

Interspersed in and around the regulators are four precisely-jumping displays. At the 12 o’clock position appears the outsize date for the first time on a RICHARD LANGE model. The day-of-the-week and month show through rectangular windows to the lower left and right respectively. And finally, a small round aperture next to the 15-minute mark reveals a leap-year indication. The perpetual calendar function is accurately programmed until the year 2100.

The last instalment on the dial occurs at 6 o’clock. A curved slot-shaped aperture exposes a numbered disc to indicate the power reserve. The RICHARD LANGE PERPETUAL CALENDAR “Terraluna” boasts a 14-day (336-hour) power reserve when fully wound. The indicator communicates to the owner when it’s time to provide the movement with fresh energy, via the winding crown. Such an enormous amount of stored energy presents a challenge. To ensure consistency of rate of accuracy across the entire 14-day period requires a particular method of delivery.

The Calibre L096.1 and patented constant-force escapement

The massive 14-day power output is produced by the twin mainspring barrel manufacture calibre L096.1. The energy supply comes from the unwinding of the two 7-day-long mainsprings. Without a form of control these springs would deliver an enormous burst of torque up front and then taper off as the uncoiling nears the end. An inconsistent rate of power supply translates to an inaccurate rate of time. To avoid this, A. Lange & Söhne developed its own constant-force escapement. The mechanism makes a correction to the rate every 10 seconds. This keeps the force distributed through the going train (movement wheels) uniform for the entire power reserve period.

The correction occurs at the fourth wheel (that drives the seconds hand). A triangular cam attached to the arbor controls a pivoting lever to recharge a pretensioned remontoir spring. The remontoir spring in turn transfers the energy to the escapement group. Thus, maintaining the oscillation of the balance at the correct rate. The constant-force escapement is visible in the exposed section of the movement. (To the upper right of the balance wheel.) Much of the rest of movement is hidden by the moon-phase display. But, as is customary for A. Lange & Söhne, untreated German silver and black polished screws feature prominently. The number of parts total 787, with 80 jewels and one gold chaton. Visible and of note is the hand-engraved balance cock with swan-neck regulator.



To make an appointment to view the RICHARD LANGE PERPETUAL CALENDAR “Terraluna” please contact your nearest Watches of Switzerland Boutique without delay. It is highly unlikely we will see another example of this exclusive timepiece in Australia any time soon. 

Discover the details of the watch here.

Find out more about A. Lange & Söhne here.

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