It's a Lange thing. That "thing" (also seen at Patek) where a most meritorious feature is often tucked around the back hidden from sight. Then there's the knack for displaying a wealth of indications on a dial while maintaining readability and elegance - that's also very "Lange".
This is the newly unveiled A. Lange & Söhne Perpetual Calendar Terraluna, a piece which features some serenely overlapping dialside displays and also some out-of-sight excellent stuff which is only visible when you flip it over.
On the dial, the large minutes receives domination at the centre, with the hours at the right and running seconds at the left. There is more than a little equipoise in the placing of an aperture in each of the lower dials - for month and day of month - equilibrium for the Big Date apertures at the top.
Look closer and you will notice that a little slice of the lower dial has been opened to reveal a power reserve indicator .... look closer still and you'll see the curious little porthole display for the leap year over by the crown.
The instant date change at the midnight hour of all indications makes for an engaging spectacle and a watchmaking conundrum for the Masters at Lange who have had to engineer the boost of power needed for this along with smooth deliverance of power in a reserve of up to a remarkable 14 days.
Turn the piece over and the Calibre L096.1 reveals that its three-quarter plate is in fact an orbital moonphase which shows the relative locations of the sun, moon and the earth via three discs. A 24 hour scale engraved onto the movement even allows for time reading. This unique display which is patent-pending adds a most accurate and visually appealing replication of the night sky to the Haute Horlogerie collection at A. Lange & Söhne.