Through the alignment of Khufu's two southern shafts with the Sun (Re) and Moon (Thoth Horus), the ancient Egyptian astrologer-priests were able to accurately pinpoint forthcoming eclipses, the flooding of the Nile, anchor their calendar to the true year, and set religious feasts. Furthermore, investigations demonstrate a cohesive, evolving plan from Huni to Menkaure, spanning Syene (Aswan) to Giza, by virtue of the interplay of light with the pyramidal structures built by them along the course of the Nile. In them, are to be found solar signalling of the annual Nile flood, which allowed the astrologer-priests to take their measurements of the flood levels and make accurate predictions as to flood levels downstream. Upon this basis, the productivity of the forthcoming season would be calculated and taxes set. A new chapter in the understanding of ancient Egyptian culture is dawning, casting light over legends that were once shrouded in mystery. Links Tomb of Osiris, Aswan, Syene, Re, Thoth, Horus, eclipses, Nile flood levels, Red Nile, Green, White, Blue, calendar, seasons, Akhet, Proyet, Semut, solstice, summer, winter, equinox, spring, autumn, fall, harvest, Djoser, Step Pyramid, Masoudi, Apophis, King Lists, Manetho, Huni, Sneferu, Khafre, Menkaure, Elephantine, Fayyoum Oasis, Edfu, Kula, Naqada, Abydos, Minya, Meidum, Dashur, Bent, Pyramid, Cerny, Sokar, Enneads, Red Pyramid, Pyramid Texts, Dynasty V, Old Kingdom