Mikołaj Kopernik, camera obscura i Krakowska Szkoła Astronomiczna

This paper offers a discussion of a series of observations made in Frauenburg by Nicolaus Copernicus. The series was recorded by Copernicus in his copy of Johann Stoeffler’s Calendarium Romanum Magnum (Oppenheim 1518), and concerns four partial solar eclipses that occurred in 1530, 1536, 1540, and 1541. It is argued that Copernicus employed the camera obscura (pinhole camera) to measure the magnitude of these eclipses. This conclusion allows us to strengthen a thesis previously formulated by Ludwik A. Birkenmajer and to propose that the astronomical use of images formed through an aperture, which spread among European astronomers in the second half of the sixteenth century, may have its source in eclipse measurements made by Copernicus during the later years of his scientific activity. It is also argued that the scientific community at Cracow seems the most obvious environment where Copernicus might have learned about the astronomical use of a camera obscura.