4 easy tips how to read the Astronomical clock in Prague

How to read the Astronomical Clock? How does it work and how to understand what it really shows you? This sophisticated mechanism constructed in 1410 for Prague is fascinating, but you know what? Almost nobody knows exactly what it shows! Without learning how it works, it’s just a mix of hands, circles, three different sets of numbers, various objects, zodiac signs and colorful fields. So, where to start? This blog post will teach you how to easily read and understand the Prague Astronomical Clock. In 4 simple steps. Ready?

how to read the astronomical clock in prague
Prague Astronomical Clock in the morning. It will be all yours!!! No crowds, no loud tour groups. This photo was taken by myself and it´s not photoshoped:-)) The place was completely empty.

Who is writing you this blog post?

My name is Dana and I am a Prague local. And also a solopreneur in the travel industry. I am running my own tiny business called Prague Behind The Scenes, and showing my clients around Prague in a less touristy way. To help them enjoy Prague in a more authentic way. I am also an active blogger (yes, this content was written by me, not by artificial intelligence – real brain and real hands, hohoooo!).

I am regularly posting practical or unusual information about Prague on the website you are currently browsing:-) and in this blog post I would like to teach you how to read the Astronomical Clock in Prague. In a more understandable way. The way I learnt it myself a couple years back. And no worries if you don´t get it right away. It also took me many hours and visits to the Old Town Square to see how it really works. 

Question, comment, tour requests? 🙂 Please feel free to get in touch, I am not an anonymous company: dana@praguebehindthescenes.com

Few practical things before you go to visit the Astronomical Clock in Prague

  • Go there early. I know, I know….you are on holiday and you want to have a good sleep, enjoy hotel breakfast, etc…BUT, believe me, it’s so much worth it to wake up early one day and be at the clock before the crowds come.  
  • Best time to visit is before 8am. To enjoy your space and explore the sophisticated functions of the clock without large groups of people around you (check the pictures below and find approx. 1000 differences:))
  • The tower with the Astronomical Clock is actually open to the public! You can walk up to the top. On the first opening hour there is a 50 % discount on the entry. The clock itself – for watching it from the square is free of charge, open 24/7!!!
  • Smiiiile and wave at the camera: if you want your friends or family to see you by the Astronomical Clock, you can send them a link to the live camera streaming the Old Town Square 24/7. It also shows you how crowded or empty the square is. This is the link. The camera goes live after a commercial – please be patient:))

1. How to read the Astronomical Clock in 4 easy steps. First, learn where to look!

You are maybe laughing now. But you know what? Many tourists often think that the actual Astronomical Clock is the parade of the 12 Apostles who show up every whole hour in the windows at the top of the tower. This is not it:-)

Hundreds of people gather under the Astronomical Clock tower every hour just to see the Apostles. Then they clap their hands and leave. Often disappointed as they don´t understand the “must-see hype” about it – 1 minute show and that’s it?

The show of Apostels. Every hour you can see them in small windows above the Astronomical Clock dial (astrolabe). In each window there are 6 Apostels with their atributes – symbols (St. Peter with a key, St. Paul with a sword and book, St. Philip with cross…)

Guys, this is a mistake. The applause should go to the persons who constructed the two dials lower on the tower. This is actually the part of the Astronomical Clock people should come to admire. It consists of two parts: the astrolabe (upper colorful circle) and a calendar board (the lower circle).

Once you learn how to read the Astronomical Clock, you will never come back during the whole hour to see the Apostles. You will want to come back between the shows. And best before 8am. Before the crowds come!.

2. What are all the elements and numbers on the clock?

First off, we need to familiarise ourselves with all the important elements on the clock, then I will explain to you what they actually show you.


There are three sets of numbers on the dial: Gothic numerals, Roman numerals and Arabic. Each set will show you a different type of time. The Gothic numerals show you Old Czech time, Golden Roman numerals show you the current time we actually use these days and the Arabic numerals show you Babylonian time. And as a bonus, the clock also shows Siderial time – but this is more related to astronomy than time.

There are three sets of numbers on the clock: Gothic, Arabic and Roman numerals.


Now look at the colors of the dial. There are three different fields, right?

Blue = daylight when the sun is above horizon, orange field represents the actual local horizon and also two parts of the day: dusk and dawn when the sun is below horizon. The black field is the astronomical night.

In the lower blue field and orange field you can also see four latin words: on the left side it´s AURORA (dawn), ORTUS (sunrise), on the right side OCCASUS (sunset), CREPUSCULUM (twilight, dusk).

The center of the whole clock (where all the hands cross) is the Earth and position of Prague on the Northern Hemisphere.


One of the black poles carries a symbol of a golden hand (on the same pole is also a symbol of a sun). This hand is very important for us. Because it shows you the Old Czech Time and also the current time! Wait for the explanation.

Very important parts of the clock: sun and a hand. Original photo: Prague.eu / text and description: Prague Behind The Scenes.


Is on the same pole as the golden hand. The symbol of the sun is moving up and down during the day – according to the real position of the sun in the sky above you (when it’s in the blue field, it’s a daytime, when the sun is in the red field it´s either dawn or dusk, when in the black field it means it´s night). It also shows you what zodiac sign we are in and also a date. I will write about it, too.


That´s the black and sometimes silver ball on the dial – please see the picture above. This metal ball is rotating according to the current moon phase! That’s why half of the ball is silver and half is black – to present what moon phase we are in. That’s basically what we see in the sky at night, sometimes full moon, sometimes only a tiny crescent…


Inside the astrolabe you can also see another circle – golden with black background – depicting all 12 zodiac signs. But wait – around each sign you can also see such tiny golden beams, fields. They represent days! Each field symbolises approx. 5 days. As you can see, some fields with the zodiac sign are wider, some are smaller. It doesn’t mean that some months are longer and some shorter. The sizes show you how much daylight you have in each month and how high the sun goes above the horizon. The winter zodiac signs have smaller fields, while the summer ones have bigger ones.

how to read the astronomical clock in prague
The tiny blue windows are the windows with Apostles. Lower on the tower is the astrolabe. The very first and oldest part of the clock from 1410. The bottom circle is a calendar board, added to the astrolabe ca 80 years later. The Apostles are probably from the 17th or 18th century, it’s not 100% sure.

3. How to read the time and everything else?


First I will teach you how to read the current time: find the golden hand with two pointing fingers. Got it? Then look at the Roman numerals. Voilá, the Roman numerals and the golden hand will show you the current time. The mechanism is super smart but unfortunately is not set for the summer – daylight saving time). When you are visiting Prague in summer, make sure you add +1 hour when looking at the Astronomical Clock.


  This type of time is great. It’s the type of time used in the Czech lands when the Astronomical Clock was constructed (around 1410). The old Czech time shows you how much daylight is left until the sunset. Why was this so important? People needed to know how long they can work outside or how far they can travel (safety – the roads and streets were not lit up).   

So, how to read the old Czech time: again, search for the golden hand with pointing fingers. The hand is pointing to the Gothic numerals (the outer black circle). Then count toward the right until you reach Gothic number 24. The old Czech time had 24 hours but didn´t start with the midnight, it always started with the sunset.


  This is one of the oldest times in the world and Prague Astronomical Clock is the only astronomical clock in the world that can still measure it. It´s calculated from the sunrise until the sunset (1 – 12 hours). How to read it? Search for the symbol of the sun and then look at the black Arabic number above it. This time, for us, doesn´t make much sense. But it´s sometimes used in the Jewish liturgy. And it´s absolutely fine if you don’t understand its meaning. Me neither. Honestly, my head explodes at this moment. If you are interested in more details and you are a technical geek (I am not!!!!), please visit a website Orloj.eu


The symbol of the sun is on the same pole as the pointer (hand with pointing fingers). It’s going up and down as the sun in the sky. It also sits in the current zodiac sign. Just look at the zodiac sign circle. The zodiac circle is rotating and copying the way of the sun pole. Then you will always know what zodiac sign we are in.     

4. Calendar board – what does the bottom circle show you?

This part will be much simpler. I promise. The calendar board is the circle under the astrolabe (the upper circle) and was added to the mechanism at the end of the 15th century.

how to read the astronomical clock in prague
Under the astrolabe you can see this beautiful calendar board.

Can you see the outer light grey circle? It’s full of names. It’s not very well visible from this picture but there are 365 fields and on every single day falls a name day. Yes, we celebrate name days here! Nowadays we celebrate the civil names like Dana, Katerina, Ivana…but back in the days people celebrated saints and patron saints. That’s why in each field you can find the name of the saint. Or the name of some religious holiday. Every day, after midnight it moves clockwise by one field. The current date and name of the saint you can see at the top. The tiny golden arrow is pointing there.

how to read the astronomical clock in prague
Allegories of the 12 month, 12 zodiac signs and in the center you can find the old coat of arms of the Old Town.

There are also bigger and smaller circles with pictures. What do they depict? The big circles represent each month of the year and depict activities people in the countryside usually did during the particular month. The small circles represent – again – zodiac signs. The whole calendar is rotating as well and the golden arrow at the top is pointing towards the current month and zodiac sign.

But this is not all….

This blog post was only a brief introduction:-) You can see much more details on the Prague Astronomical Clocks. But I believe this scope of information was enough for the beginning. Next time I will explain you more.

Thank you very much for reading it. Hope you will find it useful durign your Prague stay.

Dana, owner and fully certified guide for Prague Behind The Scenes | small-group tours and experiences.

Please feel free to contact me if you have any questions or want to see Prague with me: dana@praguebehindthescenes.com

You can also follow Prague Behind The Scenes online for more inspiration.

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