The timepiece comprises means for indicating the sunrise and sunset taking account of seasonal variations. These means comprise a sphere reproducing the terrestrial globe, a shell arranged concentrically to the sphere and arranged to demarcate one portion of the terrestrial globe where it is night from another portion where it is day by indicating the position of the Earth's terminator. The shell can pivot about the globe on two axes perpendicular to each other. The shell is driven by the movement so as to rotate at a rate of one revolution per 24 hours about the polar axis. A disconnecting mechanism is controlled by an annual cam which has a profile representative of the tilt of the Sun with respect to the equatorial plane. The disconnecting mechanism controls the tilt of the shell about the axis by means of a drive shaft concentric to the polar axis.