Source: Images and content by Jaeger LeCoultre @ Jaeger LeCoultre.
A New Complication and a Captivating Display
The new Calibre 590 was entirely conceived, designed and constructed within the Manufacture Jaeger-LeCoultre and assembled in the Atmos atelier, a workshop solely dedicated to Atmos. Comprising 443 components, with the tellurium complication fully integrated into the movement, it required more than four years of research and development – its technical complexity and sophistication naturally meriting a place in Jaeger-LeCoultre’s Hybris Mechanica collection. As well as reproducing with precision the rotation of Earth on its own axis, and the orbits of the Moon around Earth and Earth around the Sun, the new calibre indicates the corresponding months and seasons with a zodiacal calendar.
The clock face is defined by a peripheral ring formed of two layers. The upper layer, fixed in place, is marked with an hour-and-minute track and the names of the seasons; this conceals a mobile ring marked with the months, which appear in an aperture at 6 o’clock. Set within this frame is a disc of translucent blue sapphire crystal, laser-engraved with the zodiac signs. At the centre of the dial, the sun is represented by a burst of polished golden metal rays.
Close to the peripheral ring, balanced by a wedge-shaped counterweight, a circle of meteorite frames a transparent sapphire disc into which a spherical Earth and Moon are set. The Earth rotates on its axis in 24 hours, the length of a civil day, providing a night-day indication as it revolves. At the same time, the Moon orbits Earth in one synodic month, turning on its own axis to show its phases. Defined by one complete cycle of moon phases, a mean synodic month is 29 days, 12 hours, 44 minutes and 2 seconds in length. This mean (or average) duration allows for the slight variation caused by the elliptical shape of the Moon’s orbit. The mechanism of the Atmos is so close to this mean that it creates only one day of error in 5,770 years.
This entire Earth-and-Moon disc orbits around the central Sun, making a complete rotation in one solar (or “tropical”) year, indicating the seasons as it turns. Jaeger-LeCoultre’s watchmakers have succeeded in establishing a cycle of 365.2466 days. This is so close to the reference value of 365.2425 days found in the Gregorian calendar that it varies by only one day in 390 years, meaning that it will not need adjusting until the year 2412 (the only adjustment is the seasonal change).
‘Fully visible from every angle, the entire mechanism seems to hover in space within its cylindrical cabinet of glass. In fact, it is supported, and attached to the base by a virtually invisible glass cloche, which also encloses the annular balance. Like the main body of the movement, the balance also seems to floating as it performs its slow and mesmerising dance.’ explains Lionel Favre, Jaeger-LeCoultre Design Director.