The Prague Astronomical Clock

The Prague Astronomical Clock is a medieval astronomical clock located in Prague. The clock was first installed in 1410, making it the third-oldest astronomical clock in the world and the oldest one still working.

What is so Wow about this clock is mechanism which is composed of three main components: the astronomical dial, representing the position of the Sun and Moon in the sky and displaying various astronomical details;

“The Walk of the Apostles”, a clockwork hourly show of figures of the Apostles and other moving sculptures—notably a figure of Death (represented by a skeleton) striking the time; and a calendar dial with medallions representing the months.

600th Anniversary

On October 9, 2010, the Clock’s 600th anniversary was celebrated with a light show on the face of the clock tower.

The astronomical dial

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.

Stationary background

The background represents the Earth and the local view of the sky. The blue circle directly in the center represents the Earth, and the upper blue is the portion of the sky which is above the horizon. The red and black areas indicate portions of the sky below the horizon. During the daytime, the Sun sits over the blue part of the background and at night it sits over the black. During dawn or dusk, the mechanical sun is positioned over the red part of the background.

Zodiacal ring

Inside the large black outer circle lies another movable circle marked with the signs of the zodiac which indicates the location of the Sun on the ecliptic. The signs are shown in anticlockwise order. In the photograph accompanying this section, the Sun is currently moving anticlockwise from Aquarius into Pisces.


The golden Sun moves around the zodiacal circle, thus showing its position on the ecliptic. The sun is attached to an arm with a golden hand, and together they show the time in three different ways.


The movement of the Moon on the ecliptic is shown similarly to that of the Sun, although the speed is much faster (due to the Moon’s own orbit around the Earth). The half-silvered sphere of the moon also shows the Lunar phase. Moon is on the 379 teeth gear inside the machine.


The four figures flanking the clock are set in motion at the hour, these represent four things that were despised at the time of the clock’s making. From left to right in the photographs, the first is Vanity, represented by a figure admiring himself in a mirror. Next, the miser holding a bag of gold represents greed or usury. Across the clock stands Death, a skeleton that strikes the time upon the hour. Finally, the Turk tells pleasure and entertainment.

There is also a presentation of statues of the Apostles at the doorways above the clock, with all twelve presented every hour.

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