Facebook Twitter

Ancient astronomers of the Colorado Plateau and how they aligned their buildings

Many of the structures built by Ancestral Puebloans at Chaco Canyon, in New Mexico, are astronomically aligned

SHARE Ancient astronomers of the Colorado Plateau and how they aligned their buildings

Chaco Canyon under the Milky Way.


It isn’t necessary to travel to Mesopotamia, the Nile Valley, the Peruvian Andes or even the high plateaus of central Mexico in order to visit the ruins of mysterious pre-modern civilizations.

For example, Chaco Canyon, located in the northwestern quadrant of today’s New Mexico — in what is often termed the “Four Corners” region, where Arizona, Colorado, New Mexico and Utah meet — was central to the lives of thousands of Ancestral Puebloans from A.D. 850 until its virtually complete abandonment by about A.D. 1250, possibly as a result of climate change and resulting drought. (The Ancestral Puebloans are often known as the “Anasazi” — a Navajo term that means not “ancient ones” but “ancient enemies,” and has thus lately fallen out of fashion.)

Chaco Culture National Historical Park became a UNESCO World Heritage Site in 1987, joining such illustrious places as Vatican City, Egypt’s pyramids plateau and the Grand Canyon.


Pueblo Bonito at Chaco Culture National Historical Park, a UNESCO World Heritage Site in New Mexico. This canyon was inhabited by the Ancestral Puebloans, or Anasazi.


Some have suggested that the very site of Chaco Canyon was chosen for astronomical reasons — and that, perhaps like certain Mesoamerican building complexes and like the ancient stone temples of Malta, it was more religious center than town. Certainly, many of its buildings are astronomically aligned. Even today, the Chaco Canyon area enjoys perfectly clear night skies for astronomical observation. In August 2013, it was officially designated an International Dark Sky Park.

Because our Earth is tilted, the rising and setting of the sun appears to move along the horizon and the days grow longer and shorter as the planet moves through its annual orbit. This is why we have seasons. In the northern hemisphere, the longest day — the summer solstice (“sun standstill”) — comes on or about June 21. In the southern hemisphere, that day is the winter solstice, the shortest day of the year. Six months later, on Dec. 21-22, summer solstice occurs in the southern hemisphere and winter solstice in the northern.

Halfway between the solstices are two days — the spring or vernal equinox and the autumnal equinox — on which every Earthling enjoys equal periods of daylight and night. (“Equinox” means “equal night.”) On these days, the sun rises directly due east and sets directly to the west.


The ruins at at Chaco Canyon in New Mexico.


At Chaco, 15 major complexes were created from local sandstone and from lumber that may have been hauled from up to 70 miles away. Until the 19th century, they were probably the largest buildings ever constructed within the boundaries of today’s United States. The largest of them (and the most intensely studied) is Pueblo Bonito, which contains slightly less than 700 rooms and, at some places, was four or perhaps even five stories high. Pueblo Bonito forms a semicircle whose straight boundary runs precisely east-west. It is bisected by a wall that is north-south, so that, as the sun passes overhead at midday, it casts no shadow.

The great Casa Rinconada “kiva” or ceremonial space is also aligned with the cardinal directions, with entrances on the north and south sides. There are many kivas at Chaco; their round designs may have been intended to reflect the circle of the sky overhead.

From the complex at Chaco, mysterious “roads” radiate off in many directions. The most impressive is the “Great North Road,” which goes in an absolutely straight line, deviating for no obstacle. (Not even cliffs interrupt it: Where required, narrow, dangerous stairs continue the northward route.) It may have been considered a two-way path connecting Chaco Canyon with a spiritual homeland to the north.

The sheer and dramatic Fajada Butte provides one of Chaco’s most famous astronomical features, the “Sun Dagger”: Until shifting in 1989, three massive sandstone slabs allowed noon sunlight on the summer solstice to precisely bisect a spiral petroglyph etched into a stone wall and to frame it precisely at winter solstice noon. Moreover, a nearby cliff painting may memorialize the sighting of a July 1054 supernova that is known from contemporary Chinese astronomical records as well as Japanese and Arabic accounts and that resulted in the Crab Nebula.


Kiva ruins at Pueblo Bonito at the Chaco Culture National Historical Park in New Mexico.


Some have suggested that the idea of designing buildings oriented to the regularities of the astronomical cosmos represented an attempt to bring that orderliness down to our chaotic existence on Earth and to live lives in harmony with the natural cycles of the calendar. Still today, the Hopi and Pueblo peoples consider Chaco Canyon sacred.

Similar astronomically-aligned structures are found at Hovenweep, which straddles the Utah-Colorado border. And another fascinating Amerindian astronomical site is southern Utah’s Parowan Gap.

Daniel Peterson teaches Arabic studies, founded BYU’s Middle Eastern Texts Initiative, directs MormonScholarsTestify.org, chairs interpreterfoundation.org, blogs daily at patheos.com/blogs/danpeterson, and speaks only for himself.