Timepiece comprising a day/night display that takes account of seasonal variations

A timepiece comprising:

• a timepiece movement;
• a calendar mechanism;
• and
• means for indicating the sunrise and sunset that take account of seasonal variations,
• the timepiece movement comprising a minute wheel set, a motion work, an hour indicator member, and an hour wheel set integral in rotation with the hour indicator member and arranged to be driven by the minute wheel set via the motion-work, either at a speed of one revolution in 12 hours, or at a speed of one revolution in 24 hours,
• the calendar mechanism comprising means for displaying the date arranged to be driven via the hour wheel set, and a month display arranged to be driven by the means for displaying the date,
• the sunrise and sunset indicating means comprising a sphere replicating the terrestrial globe and a ring mounted concentrically to the sphere and arranged to indicate the position of the earth's terminator, the sphere being arranged to be driven to rotate at a rate of one revolution in 24 hours about a first axis corresponding to the polar axis of the terrestrial globe, and the ring being mounted in order also to be able to pivot relative to the sphere about a second axis intersecting the first axis perpendicularly at the centre of the sphere,
• the sunset and sunrise indicating means further comprising an annual cam having a profile representative of the tilt of the sun with respect to the equatorial plane, and arranged to be driven in rotation at a rate of one revolution per year, the plane subtended by the ring forming with the first axis an angle equal to the angle of tilt of the sun with respect to the equatorial plane,
• wherein the timepiece movement comprises a second kinematic chain connecting the hour wheel set to the sphere, so as to drive the sphere at a rate of one revolution in 24 hours,
• wherein the timepiece movement comprises a manually actuatable time change mechanism arranged to pivot the hour wheel set step-by-step independently of the motion work, and a disengagement mechanism arranged to disengage the second kinematic chain when the time change mechanism pivots the hour wheel set to change from summer time to winter time, or vice versa, so that the sphere can be driven at a rate of one revolution in 24 hours, without being affected by the summer time/winter time correction, and
• wherein the annual cam is arranged to be driven by the means for displaying the date via a third kinematic chain.