Science  /  Discovery

Is Colorado Home to an Ancient Astronomical Observatory? The Question Is Testing Archaeological Limits.

Did Ancestral Puebloans watch the skies from Mesa Verde's Sun Temple? Solving its mysteries requires overcoming archaeology’s troubled past.

“It’s sheer genius,” Towers said of Sun Temple’s construction. “The architect did this with no known writing or numerical system, no computers. They laid it out with yucca cords and sticks. They were the Michaelangelo of their time.”

Mesa Verde National Park, established in 1906, features some of the most well-preserved Ancestral Puebloan sites in the Southwest. More than 22,000 people may have lived on and around Mesa Verde at the beginning of the 1200s. But by the beginning of the 1300s, the area was depopulated, likely as a result of a prolonged drought or other social pressures. The inhabitants largely resettled in Arizona and the Rio Grande Valley of New Mexico, where their descendants live today as the Pueblo and Hopi people. (The park’s former inhabitants were once called the Anasazi, though the term – which is commonly cited as meaning “ancient enemy” in the Diné language – is considered derogatory by Pueblo people and has fallen out of use).

Mesa Verde’s crown jewels are its cliff dwellings, sprawling structures built in alcoves beneath the mesa tops, with likely uses including habitation, food storage, ceremony and ritual. More than 600 cliff dwellings are scattered throughout the park, though they represent just a fraction of the more than 5,000 known archeological sites within park boundaries.

Amid this archaeological treasure trove, Sun Temple stands out.

Built nearly 800 years ago by the Ancestral Puebloans, Sun Temple shows no signs of habitation – no hearths, no food storage, no trash middens. The D-shaped 122-foot-by-64-foot structure encloses several roofless circular rooms. They do not appear to be kivas, the subterranean rooms used for ceremonies and rituals. Nor were they tall enough to be watchtowers. 

“We know it’s monumental public architecture,” said Elizabeth Dickey, Mesa Verde National Park’s head of cultural resources. “But how was it used? That we can’t say.”

Finding alignments

Towers’ work follows earlier hypotheses about the site’s astronomical alignments, dating to the earliest modern researchers. Sun Temple was first excavated by J.W. Fewkes, a pioneering archaeologist and ethnographer who worked in the park in the early 20th century – and gave Sun Temple its modern name. Fewkes theorized that Sun Temple’s south wall was aligned to the summer solstice sunrise, though later investigation found the wall is off from the sunrise by several degrees. 

Nevertheless, in the decades that followed, researchers built on Fewkes’ theories, owing in part to Sun Temple’s commanding view of the surrounding landscape, and growing awareness of the Ancestral Puebloans’ knowledge of astronomy.