The clock in the Strasbourg Cathedral with the image of Nicolaus Copernicus

The painting placed in the astronomical clock from 1574 is the work of Tobias Stimmer (1539–1584). Based on the presumed self-portrait of the astronomer, provided to the artist by Tiedemann Giese from Gdańsk. This portrait is considered lost and was supposed to have been created between 1503–1509. Nicolaus Copernicus, as a freshly graduated physician at the beginning of the 16th century, was depicted on the portrait with a lily in his hand and an inscription confirming that the painting was based on his self-portrait: „ex ipsius autographo depicta”. At the bottom of the image, the artist placed a compass, a sphere, a pyramid, and a book. According to research conducted by Professor Józef Flik, the portrait in the clock, „of moderate artistic value”, could not have been the work of Tobias Stimmer. X-ray analysis showed that the original Strasbourg portrait was most likely repainted during the clock’s renovation, which was carried out in the 19th century. The inspiration for repainting was supposed to be the so-called „Toruń portrait of Copernicus” copy from Paris dating back to 1735.