Midday Shadows and Functionality of Central Pillars in Enclosure D at Portasar (G¨obekli Tepe)

This study investigates the potential shadow-tracking functionality of Pillars 18 and 31 in Enclosure D at the Pre-Pottery Neolithic site of Portasar (G¨obekli Tepe). Based on simplified threedimensional modeling, photometric analysis, and simulations using Stellarium 24, the research focuses on the midday shadow dynamics during the year’s key solar events: the solstices and equinoxes. The findings indicate that the grooves on the upper sections of the Pillars, as well as symbolic carvings—such as the bucranium, the “H” symbol, and the “lunisolar” motif—may have served as solar or lunar shadow markers aligned with the culmination points of the Sun and the Moon. Specifically, the bucranium appears to correspond to the culmination of the Taurus constellation (particularly the Pleiades), while the position of the “lunisolar” symbol coincides with the equinoctial noon and possibly with lunar or solar eclipses. These results support the hypothesis that the central Pillars functioned as an integrated shadow-measuring system, potentially enabling Early Neolithic communities to mark key calendrical thresholds throughout the year.