Perpetual Calendar With Leap Year

This grand complication’s perpetual calendar comprises month and day of the week displays at its one o’clock position, and a day of the month sub-dial at its three o’clock position indicated via a serpentine-shaped hand. A small number beside this dial indicates whether it is a leap year or not. This entire perpetual calendar involves a mechanical memory of 1,461 days and will not require adjustment until the year 2100.

Sunrise, Sunset And Length Of Day

At the six o’clock position on the dial, two sectors show the sunrise and sunset hour, while a linear meter indicates the length of the day in gold and the length of night in black. This truly uncommon complication facet has to be specifically customised to the latitude of its owner. Upon order, a disc is tailored to calibrate the length of day of the latitude in question and two cams are engineered to keep track of sunup and sundown for that latitude.

Equation Of Time Marchant

A yellow gold pointer fashioned with a radiant sun at its tip indicates actual solar time. As each rotation of the earth on its axis in the 365-day calendar year is usually longer or shorter than 24 hours, the marchant (French for “walking”) points out how much actual solar time is ahead or behind universal civil time.

Signature-Style Tourbillon

Hidden at the back of the watch, the vaunted Vacheron Constantin tourbillon diligently chugs to counteract the effects of gravity that would otherwise affect its chronometry. The gilded tourbillon bears the Maltese cross, the signature motif of the Genevan brand. 

Three-Week Power Reserve

Storing up to 21 days of reserve power within a 36mm-movement is a feat that cannot be overstated. This grand complication is capable of storing its massive amount of potential energy within six mainspring barrels, thanks to the shape memory alloy Bioflex that they are precision-engineered from, which helps cope with the varying amounts of tension exerted on the spring as it steadily releases energy to tell the time. Its remaining power ticks down dramatically on its caseback, counter clockwise from its 12 to six o’clock positions.

Zodiac

Beside the sunset indicator, a small disc reveals the sun sign zodiac of the month as well as the solstices and equinoxes.             

Mareoscope

The mareoscope is a delicate feat of high-accuracy mechanics that indicate the rising and falling of the tides, contingent on the moon’s rotation around the earth. This feature makes for a majestic decoration. 

Precision Moonphase

A traditional moonphase hand-finished in the style of Vacheron Constantin adds to the dial’s many complicated embellishments. Moving across a range of 29½ days, the watch hides the moon display from sight by day.

Celestial Chart

The Celestia’s heart-stopping caseback showcases a map of the stars—the ones close enough to be visible from earth, at least—via two superimposed discs. A lower disc that rotates once per day indicates sidereal time. Completing this planisphere, a transparent disc in the fore reveals the stars that are currently visible. A white ellipse demarcates the Celestial Equator while a red ellipse demarcates the Elliptic Equator. All these moving parts revolve around a central axis, the Alpha Ursae Minoris, also known as the Polaris star, which is the only star that does not move in the Northern Hemisphere’s night sky and to which navigators have looked to for bearing since time immemorial. 

(Related: Why the Vacheron Constantin Overseas Worldtime Watch Will Change Your Life)

Sidereal

Sidereal time can be read along the circumference of t caseback. Sidereal time is time on earth as determined by earth’s surrounding heavenly bodies. Disregarding solar and civil time, sidereal time stipulates each day as 23 hours, 56 minutes and four seconds long.