JACOB & CO. Astronomical Sky, Sidereal Time Jacob & Co. draws inspiration from historic astronomical clocks, which are technical marvels. Known for its captivating complications, the brand is back once again with the Astronomia Sky. It combines unprecedented complications: a 3D star display combined with an oval sky indicator and a 24-hour day/night display.

Jacob Arabo, founder of Jacob & Co, said: "Like a sailor at sea, led by the sky, I found my star: the sky of astronomy." In 2014, he launched the wristwatch The watch took the watch industry by surprise. Astro-gravitational three-axis tourbillon.

The celestial dial covers the inner surface of the astronomical case and completes one full revolution in a sidereal year, which is the actual time it takes Earth to orbit the sun relative to a fixed star. The blue grade 5 titanium dial features 18K gold stars and hand-engraved zodiac signs.

Above the celestial sphere is the elliptical sky indicator, which shows the portion of the star visible from the northern hemisphere. The indicator completes a full rotation within a sidereal day. A sidereal day is the time it takes for the Earth to rotate once around its axis: 23.5640916 hours.