A timepiece indicates the sunrise and sunset taking into account seasonal variations. The timepiece includes a sphere representing the Earth, a shell arranged concentrically to the sphere and arranged to delimit a part of the globe where it is night time from another part where it is daytime by indicating the position of the Earth's terminator. The shell can pivot around the globe along two perpendicular axes. The shell is driven by the movement in order to revolve at the rate of one revolution every 24 hours around the polar axis. A differential mechanism is controlled by a year cam that has a profile representing the inclination of the sun in relation to the equatorial plane. The differential mechanism controls the inclination of the shell around the axis by a drive shaft concentric to the polar axis.