First of all, what is archaeoastronomy? It is the study of how the ancients studied or used astronomy. The position of the stars in the night sky; the movement of the sun across the horizon throughout the year; the movement of the Moon across the horizon on its eighteen-nineteen year cycle; were all studied and recorded and used by the ancients as their celestial calendar. Knowledge of these cycles helped the ancients to know when to plant their crops, or migrate, celebrate their religious holidays, and many other important events during the year.
In the heart of New Mexico there is an arid canyon called Chaco Canyon that was once the center of the Anasazi culture. In this canyon stands an ominous butte called Fajada (fa-ha-da) Butte. Atop this huge 450 ft-high formation are three large sandstone slabs that lean up against the southern wall. On the wall behind these huge stones, the Anasazi astronomers chiseled two large spirals. At noon every day the sun shines between the stones and casts shaft(s) of light across the spirals. Popularly called “daggers of light”, the dagger materialize before noon in the upper left of the spiral and then spread across the spiral to project a “dagger” covering the spiral and then clears off the spiral top to bottom. It is an amazing, almost magical occurrence.