Archaeoastronomical survey of Inca sites in Peru

Sun worship was the official religion of the Inca and major monuments were apparently associated with the Sun. Because of the nearly total destruction of their culture by the Spanish, the astronomical functions of these are not completely understood. To document their astronomical contexts, I obtained sets of 14 horizon photographs at nine major Inca sites and combined them to yield 360° panoramas. To calibrate each panorama, sun sights were made with a Wild T-2 theodolite. The panoramas were used to determine the rising and setting locations for the Pleiades and Sun on known important days in the Inca's calendar. Significant finds include: June solstice established by horizon pillars above Huayna Capac's royal palace at Urubamba; a ceremonial niche at Saihuite facing toward the June solstice; cardinal orientation of structures at Vilcashuaman and Saihuite; zenith and anti-zenith solar alignments at Sacsahuaman; and terraces at Ollantaytambo toward December and June solstices.