The Prague Astronomical Clock: A Moving Masterpiece

Clocks have been used throughout history to not only tell time, but also to track the location of the sun and moon on the celestial sphere. This fed directly into the use of zodiac signs and other time related practices. One such example of these age old traditions is the Prague astronomical clock located in the Czech Republic.

This type of clock is more than just something used to tell time. It also shows astronomical information like the position of the sun, moon, zodiac constellations, and in some cases, major planets as well. These are all measured by dials present on the face of the clock.

Join us as we explore the history and mechanisms of the oldest and one of the most famous clocks in the world.

An Ancient Masterpiece

This clock is located in the capital of the Czech Republic in the Old Town Square. It was installed in 1410 which makes it the third-oldest astronomical clock in the world and the oldest clock of its kind still working. The clock itself is built with four major components:

There is a legend that the city will fall upon misfortune if the clock isn't properly maintained. Maybe that's why it's still working after all this time. Let's explore the various mechanisms of the clock in more detail:

1. The Astronomical Dial

This portion of the clock is a mechanical astrolabe which was a device commonly used in medieval astronomy. There is a stationary background that represents the Earth and the sky. This background has red and black areas that indicate the space above and below the horizon.

On the eastern and western sides of the background are the Latin terms "aurora, "ortus," "occasus," and "crepusculum" which all mean dawn, rising, sunset, and twilight respectively.

Golden Roman numbers are etched around the edges that divide the day into 24-hours according to Central European Time. There are also curved marks to indicate the "unequal hours" that measure the time between sunrise and sunset which varies throughout the year.

2. "The Walk of The Apostles" Clockwork Show

Each hour the four figures on either side of the clock face start moving. These figures represent the four things that were looked down upon at the time of the clock's construction. They are as follows:

In addition to these figures, there are statues of the twelve apostles presented each hour. During the clockwork show, the skeleton strikes the time by ringing a bell and all the figures shake their heads. This is meant to signify that they are not ready to go.

3. Zodiacal Ring 

Inside of the black outer circle is a secondary circle with the signs of the zodiac carved into it. This dial represents the sun's location on the ecliptic.

The 600+ Year History of This Clock

The oldest part of the clock is the is the mechanisms that drive the various dials. These parts date back to 1410 and were made by a pair of individuals named Mikulas of Kadan, a clock maker, and Jan Sindel, a professor of mathematics and astronomy at Charles University.

Around 1490, the calendar dial was added to the clock, along with the gothic sculptures. The figures, including the apostles, were added after another major repair in 1787. The clock was damaged again in 1945 during the Prague Uprising.

The Germans set armored vehicles and an anti-aircraft gun on fire in the Old Town Square to stop the broadcasting started by the National Committee two days prior. Several buildings burned, along with the wooden sculptures on the clock's face. The clock was repaired and working again by 1948.

On October 9th, 2010, the people of Prague celebrated the 600th anniversary of the clock. The celebration included a light show projected onto the face of the clock. The videos showed the clock being built, torn down, and showcased some of the internal mechanics and the events that occurred throughout the clock's history.

The video was extremely interactive, using two projectors to paint images across the clock's face. The projections interacted with the clock's architecture to use shadows as means of showing the passage of time, and rain falling off the arches of the clock.

Final Thoughts

Historical and ancient devices such as the Prague astronomical clock are important to cherish and preserve wherever possible. Such a device is incredible, given the amount of work and engineering that went into it.

It's sad that this is the only working specimen left in the world, but the people of Prague are keen on keeping this historical landmark functioning for the foreseeable future.