January 07, 2026

The Astronomical Clock of Strasbourg Cathedral is one of the most complex and refined examples of horological engineering in Europe. Located in the south transept of the cathedral, the current clock dates from 1843 and represents the culmination of centuries of astronomical and mechanical knowledge.

The clock is the third astronomical clock installed in the cathedral. Earlier versions existed in the 14th and 16th centuries, each reflecting the scientific understanding of its time. The present mechanism was designed by Jean-Baptiste Schwilgué, who combined precision engineering with advanced astronomical calculations.

Beyond telling the time, the clock performs a wide range of astronomical computations. It displays:

• Solar and sidereal time
• Phases of the Moon
• Planetary positions according to the Copernican system
• Solar and lunar eclipses
• A perpetual calendar accounting for leap years

One of its most remarkable features is the computation of the date of Easter, calculated accurately until the year 10,000.