The science of astronomy, this book tells us, is "the oldest of all," having been practiced for some 5000 years. The study of these ancient astronomers has been termed Archeoastronomy. The authors explain the role astronomy played in the lives of the Anasazi, who inhabited the Four-Corners region of the Colorado Plateau a thousand years ago: "Not only were these astronomers driven by their own curiosity about the natural world and its cycles of time, but they also served the needs of societies in which they lived. They advised emperors and generals, attempted to predict eclipses and conjunctions of planets, devised calendars for festivals and established dates for planting. Sometimes overtly or sometimes subtly, these ancient astronomers provided authority and legitimacy for their emperors and kings." The Anasazi certainly marked the seasons by simply watching the position of the rising and setting sun along the horizon, but they evidently also performed much more complex observations. Here are the sites the authors examine (the book does not include an overall map, so I have drawn my own):
Chaco Canyon. The religious and political center of the Anasazi, Chaco reached its height in the late 11th century. There, a spiral Sun Dagger petroglyph is pierced through its center by a sliver of sunlight at noon on the summer solstice, and on its edges at noon on the winter solstice. The Great Kiva of Casa Rinconada is aligned precisely north-south, and at summer solstice, a beam of sunlight passes through an opening in the wall of this round ceremonial chamber, lighting an opposite niche. Nearby, a famous pictograph shows the sun and crescent moon with a star that has been variously interpreted as the 1054 supernova that formed the Crab Nebula, or merely the morning star (a term for the planet Venus, which the book uses but fails to define).
Hovenweep. "At the summer solstice, sunset, a ray of light streams through a porthole in the sun room, shining on the lintel of the doorway into an eastern room ... the long, north wall of the room, along which the beam travels as the solstice approaches, could well have been scored with vertical marks indicating the planting dates for various crops." Here we see the mixture of evidence and speculation that is the process of archeoastronomy.
Chimney Rock. The authors discovered that at the maximum swing in the moon's 18.6-year north-south cycle, it rises between the twin buttes of Chimney Rock when viewed from a nearby pueblo. However, based on the topographical sketches provided, it seems to me the pueblo was built on the only fairly level spot along an easily-defensible ridge, with the moonrise perhaps mere coincidence. The authors do present tree-ring evidence that correlates phases of pueblo construction with these lunar standstills, so the hypothesis cannot be discounted.
Yellow Jacket. These mesa-top ruins contain hundreds of kivas, a prominent tower, and rows of monoliths. The authors have identified several north-south and solstice alignments among the structures.
What caused the Anasazi to flee their Four Corners homelands for the Rio Grande pueblos around the year 1200? A prolonged solar maximum (the Medieval Maximum) that brought drought and cold weather was no doubt the major cause. But the authors also suggest these sun-worshipers observed the increased sunspot activity with the naked eye and retreated in fear.
Those who study ancient cultures must be careful to see what is really there, rather than what they want to see. Every alignment of stones or structures should not automatically be endowed with profound cosmic significance. It is obvious that the lives of prehistoric peoples were intimately tied to the cycles of the sky, but how much more can we really know for sure? This book provides a fascinating glimpse into that finely-balanced process. Perhaps, despite all of the evidence we can collect, the minds of those who have gone before shall remain a mystery. Whenever we look backwards in time, our vision is by necessity imperfect.