A Primer on the Evolution of Astronomical Calendars

A special CP-LUHNA essay by Bryan C. Bates

In the world of nature, light is known to stimulate numerous biological activities. Coral reefs initiate their reproductive frenzy with the full moon following the summer solstice. Flowers track the pathway of the transiting sun, gathering the electromagnetic energy for metabolic and reproductive purposes. Bees vibrate through a complicated dance angled to the sun that conveys the exact location of pollen while accounting for the time of sun transit. Birds use the migration of the sunrise and solar pathway as one of their radar sensors in the thousand mile migrations between continents. Humans have also been using the changes in celestial sphere as a mechanism for determining when to conduct certain ceremonial-survival activities.

Over 7000 years ago, humans in the Nile Valley laid out large stones to mark the changing solar and lunar positions. This site is the earliest known purposeful construct of a calendar system developed by humans. What may well have preceded is the evolution of myths and stories that helped early agriculturalist transition from a migratory hunter-gatherer society to a sedentary agrarian society. Evidence for such a transition can be gleaned from the Fertile Crescent giving rise to the Babylonian Empire several hundred years later. Hundreds of years later, pyramids on the Gaza Desert rise in alignment with constellations known to the Pharaohs to provide wisdom, power and longevity. As impressive as the mathematics and astronomy of this civilization may seem, much more science lies within the cryptic writings of the ancient astronomers.

The Fertile Crescent was not the only place to give rise to human observation of celestial motion. On the Salisbury Plain of England, an ancient people began the meticulous construction of what we now know as Stonehenge. Stonehenge first began as a lunar observatory and then over the next 300 years evolved into the brilliant illuminated alignments of the sun and moon you may have seen on television. This activity of constructing an astronomical calendar results from the observing the concurrent changes within the biophysical (natural) world with those of the changing skies. While disconnected in our lives as we seldom see the night sky and therefore do not see the patterns of sun, moon and star movement, to the ancients, all was the same. Life to them was an outdoor experience, rather than the ceilings and lights that obstruct our view of the heavens.

In Africa, over seven different “Woodhenges” (i.e. Stonehenges made of tree trunks) have been recovered, some dating back 2000 years. India, as well as China, is rich in astronomical calendar and mythology all predating the birth of Christ. In China, the space about the North Star was the seat of the Celestial Emperor with his closest advisors orbiting about him (i.e. circumpolar constellations). Those advisors or Cabinet members of lesser power orbited the Emperor at a consecutively further distance, to the point that some advisors had seasonal power. Amongst the Aborigines of Australia, light-shadow interaction across petroglyphs and pictographs indicates times of special significance to the shamans of the Dreamland, not unlike that of ancestral Puebloan people of the American Southwest.

But the Indians of high Andes in Peru (Incas) and highlands of Yucatan (Mayans) developed some of the more sophisticated astronomies of the ancient world. Amongst the Incas, it was not the star patterns but rather the darken space between the stars that formed the “constellations”, all of which were reflective of their world. The Mayans meanwhile had intercalated the movement of Venus, the Moon and the Sun into a 37,960-day (or 104 year) repeating “Great Cycle”. The Great Cycle was made of numerous smaller ceremonial and survival cycles based upon moon phase and location, zenith passage of the sun, and the appearance and disappearance of Venus. An analogy would be the all the little cogs in a watch that tick together to maintain a synchronized motion discernable to us as the hands on a watch but known to the watchmaker (or science-priest of ancient) as the workings of the Gods within the celestial sphere.

Knowledge of these celestial patterns and the attribution of those powers to different Gods may have migrated along migratory and trade routes throughout the American Southwest. At Chaco Canyon in northwestern New Mexico, several calendar systems have been documented with numerous connections to the culture. At the Great Kiva, Casa Rinconada, the summer solstice sun rises through a window and cast light into a cubbyhole across the axis of this ceremonial chamber. There is a question as to whether the alignment was intentionally created by the ancient Chacoans as the Park Service reconstructed the window in the 1940s. Second, the Equinox sun rises over the eastern cliff and splits the Kiva into two equal halves, symbolic of the Equinox ceremony known amongst some of the Puebloan people. Elsewhere, petroglyphs show distinctive light shadow interactions as the sun migrates from south to north (winter solstice to summer solstice) or in the reverse, each time designating a time of potential survival or ceremonial significance.

Perhaps the best known of these petroglyphs is the “light-dagger” atop of Fajada Butte. As the sun migrates between the solstices, not only does the sunrise and sunset position change but so also the altitude of the sun in the sky. Set behind three slabs of rock the meridian suns sends a dagger of light across a rock face onto which the Chacoans carved an 18.6 grooved spiral petroglyph. A single dagger through the center marks summer solstice, whereas two light daggers bracketing the petroglyph mark winter solstice. The Equinox is mark by the appearance of a new dagger across a smaller spiral in the upper left corner. This petroglyphs marks the migration of the sun for each day of the year.

But perhaps more amazing is what researchers didn’t see, at least until a Nation Geographic photographer noted it in a darkroom. There are two very shallow grooves that cross the petroglyph, grooves associated with the movement (not phases) of the moon over an 18.6-year “Metonic” cycle. When a full moon rises at its maximum northern extent, it will cast a light shadow line directly down the upper groove. 9.3 years later, the moon rest at its southern maximum position and will cast a light shadow line through the center shallow groove. Culturally, there is strong evidence that the Chacoan and Puebloan peoples observed the interrelationship between the Sun and the Moon, and aspect of duality that permeates their religious perspectives. There is no indication that these people could predict eclipses; however, such observational practices can lead to determination of those patterns.

Similar alignments can be found at Hovenweep National Monument in Southeast Utah and Wupatki National Monument near Flagstaff, Arizona. At Crack’N Rock of Wupatki, a singular wall with three small portals records the seasonal timing of sunrise. But as above, the observation of the sunrise may tell the Sunwatcher which moon to observe, as what is culturally significant is the first appearance of a new crescent moon. The South portal (February cross-quarters) marks the time for the Powamu ceremony, or “earth renewal”, a time following the winter solstice when beans are planted inside the Kiva. The middle window (May cross-quarters) marks the time at which the soil temperature will support the germination of seeds and when the likelihood of a killing frost has past. The Sunwatcher of the Water-Sand Clan indicates one may now plant their corn. And the North window marks the summer solstice, but the observation is based upon the time at which the sun changes its direction of motion. Following preparations and a 9-16 day ceremony, the Katcinas or “spirit-carriers” leave the Hopi for their home in the sacred San Francisco Peaks. The Katcinas will then return as clouds bringing water during the “monsoon cycle” of the desert SW. Thus the Katcinas return to bring life.

In nearly all cases, human observation of the biophysical world, tied to that of the celestial sphere results in the development of different calendar structures that are emanating tied to the culture and the environment that supports that culture. These calendar systems are often held as sacred for they are the places where the sacred reveals itself to those trained in the science and religion of the nascent culture. Among archaeoastronomers, these sites are known as “hierophanies”. Behind the evolution of these science-priest is the acquisition of knowledge as to the patterning of nature reflect on earth as in the skies. These patterns then provide vital clues as to anticipated changes in the natural world, changes that affect the available food base, the potential success of a hunt, the timing of rain or the best time to offer prayer or sacrifice to the Gods such that life maybe sustained amongst their culture.

Follow this link to:
Archaeoastronomy in the American Southwest