PATEK PHILIPPE. A RARE 18K WHITE GOLD AUTOMATIC ASTRONOMICAL WRISTWATCH WITH SKY CHART, PHASES AND ORBIT OF THE MOON INCLUDING TIME OF MERIDIAN PASSAGE OF SIRIUS AND OF THE MOON

Reference 5102
Launched in 2002, the ‘Celestial’ is one of the most important horological complications ever developed. This astronomical wristwatch borrows the principle of the celestial canopy from the most complicated wristwatch ever produced by Patek Philippe - reference 5002, the Sky Moon Tourbillon. The nocturnal sky of the northern hemisphere rotates to show the apparent angular motion of the stars and moon as well as the progression of the phases of the moon. Hours and minutes are displayed by two pierced white hands. A delicate elliptical contour on the inside of the glass frames the portion of the sky visible from all cities sharing the latitude of Geneva. To determine the highest possible accurateness for the astronomical displays, the engineers of Patek Philippe researched 25 trillion (25,000,000,000,000) ratio combinations, showing the enormous horological challenge the model represents.

The highly sophisticated automatic movement calibre 240 LU CL consists of 301 individual parts, meticulously hand-finished in the workshops of Patek Philippe. Three sapphire crystal discs are used to simulate the orbit of the moon and the passage of the stars, hence rendering it a remarkable sense of depth. For the mechanical module for the astronomical displays the firm was granted Swiss Patent CH 688 171 B5.