The Prague Astronomical Clock

May 15, 2024


Photographer: Emanuele Nifosì
Summary AuthorEmanuele Nifosì

A marvel of mechanics, science and human ingenuity, the Prague Astronomical Clock has been in operation for over 600 years. This famous clock, located on the tower next to the Town Hall in the Old Town Square, is a scientific monument of the medieval period. Still fully functional today, it was built in 1410. As can be seen in the photo, four main elements can be distinguished:

1) In the center, the astronomical dial in blue, red and black, with golden Roman numerals (1410).

2) At the bottom, the dial with the calendar, where the main activities that took place during the year are depicted, predominantly golden in color (1490).

3) The four mobile statues, placed respectively to the right and left of the astronomical quadrant (17th century).

4) The wooden statues depicting the twelve apostles that parade at the stroke of every hour of the day, peeking out from the two small blue, light blue and white windows located in the upper part (mid-19th century).

At the center of the astronomical dial (light blue color) the Earth is depicted (immobile and placed at the center of the universe, according to the Aristotelian-Ptolemaic conception). The upper part (still light blue) indicates the day, while the lower part of the red band indicates the phases of dawn and sunset (as the writings make clear -- aurora, ortus, occasus, crepusculum). The black portion are the nighttime hours. The hands indicate the time (expressed in Roman and Arabic numerals). Furthermore, the symbols of the Sun and the Moon indicate the position of these celestial bodies in the sky over 24 hours, as they "rotate" around the Earth.

Finally, in the mobile ring located inside the dial, the 12 zodiac signs are indicated as well as the constellation the Sun is positioned in at each period of the year.

The astronomical dial, whose shape resembles the astrolabe, was designed and created by master watchmaker Nikolas zu Kadan and Jan Sindel, professor of mathematics and astronomy at Charles University in Prague. Photo taken on March 14, 2024.

Prague, Czech Republic Coordinates: 50.077298, 14.430128

Related Links:
Cibiana di Cadore and Circumzenithal Arc
The Ptolemaic System: A Detailed Synopsis