An Excellent and Rare Massive White Gold Automatic Astronomical Dual Crown Wristwatch with Sky Chart, Phases of the Moon, Time of Passage of Sirius and of the Moon, Patek Philippe & Co., Genève, Movement No. 3328277, Case No. 4295571, Ref. 5102, Circa 2002

18k, Cal. 240 LU CL, automatic rhodium plated lever movement, 45 jewels, gyromax balance, free-sprung regulator, adjusted to heat, cold, isochronism and 5 positions, 22k gold micro-rotor, stamped with the seal of Geneva, blue sapphire crystal disc for angular motion of the moon to the front, this rotating disc with a small aperture to reveal the phases of the moon, above sits the chart of sky on a separate transparent disc, with silvered Roman numerals from I to XII applied to inside as well as silvered ellipse framing the visible sky (marked out with the cardinal points), planisphere of the northern hemisphere rotates counterclockwise above the dial, skeletonized white-lacquered gold feuille hands, 18k white gold circular case with enlarged polished bezel, case band finely engraved with halved Calatrava crosses, two crowns in the band to set the time, sky chart, the lunar orbit and the moon phase, large water-resistant type screw-down sapphire crystal case display back, to reveal the movement, case, sapphire crystal disc and movement signed, with an 18k white gold Patek Philippe buckle.

Accompanied by booklets, and setting instructions, in Spanish, brown leather folders, Patek Philippe winding box and outer packaging.

The Ref. 5102 'Celestial' astronomical wristwatch depicts the planisphere of the northern hemisphere with an integrated moon phases display, successfully reproduces the configuration of the visible sky with the apparent movement of the Milky Way, the position of the moon, and its progressing phases within a lunar cycle.

On 5^th October 2000, Patek Philippe had unveiled the Star Caliber 2000, one of the most complicated pocket watches in the history of horology, with a fascinating suite of astronomical indications that was awarded with six additional patent-worthy innovations.

Six months later, Patek Philippe created the 'Sky Moon Tourbillon' with Caliber 109 - an oversized grand complication wristwatch with a miniaturized Sky Moon mechanism based on the astronomical module developed for the Star Caliber 2000.

In 2002, Patek Philippe created another important astronomical wristwatch with their celestial invention within a remarkably slim 18k white gold watchcase – Ref. 5102. Its newly developed automatic movement with the Sky Moon mechanism (Caliber 240 LU CL) composed by 301 individual parts that are meticulously hand-finished in the workshops of Patek Philippe, positively reinforced Patek Philippe’s unparalleled status in technological innovation of horology.

Different from the Sky Moon Tourbillon (Ref. 5002) which displays the celestial dial with sidereal time on the reverse side of the watch, this newly developed Ref. 5102 allows the user to admire the dance of the celestial bodies from its front at any time of the day.

This model is equipped with a highly complex and sophisticated function that is extremely unusual for wristwatches. The planisphere of the Northern Hemisphere rotates counterclockwise on its dial and is enhanced by construction of multiple stacked sapphire crystal, which moves independently at different speeds creating a mesmerizing impression of depth.

The night sky is meticulously mapped out on a sapphire crystal with the Sirius (the brightest and first visible star) as the index, rotates over a blue sapphire crystal dial that shows the angular progression of the stars relative to the meridian passage of Sirius.

At the same time, a small round aperture with adjustment index also indicates the meridian passage and the progressing phases of the moon within a lunar cycle (in a wheel with 279 teeth to reproduce the orbit of the moon). For this important invention of the Ref. 5102, Patek Philippe was awarded a Swiss Patent (CH 688 171 B5).