How many different times does the Prague Astronomical Clock show?

The oldest functioning Astronomical Clock in the world dating back all the way to the year 1410. Prague Astronomical Clock was installed in the last decade of the Bohemian Golden Age under the reign of Charles IV. The Astronomical clock show runs every hour sharp from 9 AM till 11 PM.

Prague Astronomical Clock shows four different times known as Old Czech time, planetary hours, sidereal time, and "German" hours. Which one shows the current hours? The latter illustrates the current time since the mid-16th century. "German" hours are marked with 24 golden Roman numerals along the circle of the astrolabe. You can also find old numerals on the outer frame of the clock dial that indicate Old Czech Time counted from the dawn. It was brought from Italy by the Holy Roman Emperor and Bohemian King Charles IV.

The unique mechanism of the Prague Clock not only shows us what time and day it is, but also tracks the movement of celestial bodies, or planetary hours, like the Sun and Moon. Depending on their position, predictions of upcoming events were made. People would even decide when to receive popular medical treatments such as bloodletting based on that!

The last time system was added in 1865 for astronomical purposes. Sidereal time rotation lasts 23 hours and 56 minutes.