If there ever was a watch that was meant to be worn inside out, it would be the Celestia Astronomical Grand Complication 3600 from Vacheron Constantin.

 

This unique watch boasts two dials that tell the time using 23 complications and is the fruit of five years of development and two years of design. Three methods of measuring time – civil (standard), solar and sidereal times – are all displayed, thanks to three separate gear trains, including a ‘tropical’ gear train that caters to all the solar functions.

Presented at this year’s Salon d’ International de la Haute Horlogerie (SIHH), this beautiful twin-dial timepiece highlights miniaturisation, hi-tech watchmaking and beautiful design. It is the latest addition to the maison’s Les Cabinotiers collection.

Vacheron Constantin celebrates 260 years with the 'most complicated watch' embracing innovation and tradition

On the front dial are 15 complications including civil time and solar time. Civil is the standardised method of reading the time used by everyone and is the reason we have leap years. Solar time refers to the trajectory of the sun and time is calculated by measuring its position according to the hour angle.

Also featured is a mareoscope which indicates the tide level and a 3D depiction of the earth-moon-sun alignment. A perpetual calendar only needs to be corrected every 400 years. The moonphase display at 9 o’clock only needs a one-day correction every 122 years. A sunrise and sunset indicator at 6 o’clock tells the length of the day and night. At 4 o’clock is a semi-circle dial that displays the zodiac signs, seasons, solstices and equinoxes.

On the back dial is the sidereal time, an astronomical time scale based on the earth’s rotation. Vacheron Constantin has come up with a novel way to read the sidereal hours and minutes by using two superimposed sapphire discs: the lower one features the celestial dome, celestial time minute-track and the four cardinal points; the top disc features the constellations and the equator (in white) and ecliptic (in red) lines.

The milky way and various constellations (as viewed from the Northern Hemisphere) are also featured, as well as a tourbillon at 6 o’clock. On the outer ring are the 12 monthsand a power reserve indicator. This watch gives you the impression that you are carrying the galaxy on your wrist.

The watch is powered by the mechanical, manual-winding calibre 3600, which was developed and manufactured in-house. It comes with three weeks of power reserve, thanks to its six barrels. 

 

The calibre is only 8.7mm thick – an astonishing engineering feat if you consider that it is made up of 514 components. The case is 45mm in diameter and 13.6mm thick. 

The watch bears the prestigious Hallmark of Geneva certification.

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