SIDERALIS is structured around two especially extraordinary tourbillons: Both of these tourbillons are oversized, with cages measuring 14. 9 mm - half as big again as the average. This is the largest assembly of two tourbillons ever to have existed. The tourbillons rotate in opposite directions, driving the Sideralis complication: two dises, one atop the other, which also rotate in opposite directions, orchestrating the ballet of the stars on the time dial, and revealing a succession of tiny hand-painted vignettes. The dises depict the planet Mars, the Moon, and Mercury, one after the other.