Focus on this artwork and explain the Astronomical dial.
The astronomical dial is a form of mechanical astrolabe, a device used in medieval astronomy. Alternatively, one may consider the Orloj to be a primitive planetarium, displaying the current orientation of the universe relative to the Earth.
The astronomical dial has a background that represents the standing Earth and sky, and surrounding it operate four main moving components: the zodiacal ring, an outer rotating ring, an icon representing the Sun, and an icon representing the Moon.
zodiac astronomy astrolabe planetarium medieval Sun Astronomical dial Moon