Astronomy of Shadows and Light : Athanasius Kircher 's Sundials between Geometry, Perspective and Science

In the XVII century the scientific debate revolved around the celestial wonders considered as mere application of terrestrial geometries. At the time Rome, one of the most important European theater of experimental science, had a large group of international scholars and, among them, Athanasius Kircher collaborated intensively on the transformation of the Jesuit College into an important center of scientific activity. He promoted the poetics of wonder, typical of the baroque art, as well as the philosophical and scientific temper which laid the foundations of the experimental method. This essay will deal with light and shadow projections in Kircher’s sundials, focusing on the problem of intersection between surfaces. Kircher’s sundials, basing on Optics, oversee and translate reality in mathematical terms becoming a scientific tool for the knowledge of the celestial mathematical rules and they are also an essential means for recreating empirically, experimentally, mechanically the perpetual motion of the universe. If on one hand their construction are based on the same rules of perspectiva artificialis, used by painters, on the other the symbolic function of sundials silently celebrates the encounter between light and shadow, sky and earth, space and time, configuring the epiphany of physical realities.