Life in the Southwest offers a rare opportunity for viewing of the night sky, one that few Americans have.
“We live in one of the very few places left that you can see almost as many stars as the ancient people living here and elsewhere,” said Charlie Hakes, a professor in the Physics and Engineering Department at Fort Lewis College.
For the ancestral Puebloans, a connection to the sky was a fundamental element of their culture. At locations across the Southwest, they built architectural features to track the movement of the sun and moon across the sky for agrarian and ceremonial purposes.
Today, the integrity of these sites is threatened by age, increased visitation and, in some cases, their restoration.
The ancestral people of the Southwest have a host of descendant tribes in the region, and a connection to the sky is woven into the fabric of their culture, said Jennifer Frost, interpretive ranger and astronomer at Chaco Culture National Historical Park. This connection to the sky was originally a necessity tied to agrarian practices, which required tracking the seasons to ensure crops were planted and harvested at the correct times, which they accomplished by sun watching.
Because the Earth is tilted on its axis, the sun rises and sets at different points along the horizon if viewed from the same location throughout the year, Frost said. By witnessing the changes in the location of the sun as it dipped over the mesas, ancestral Puebloans could track the seasons and place markers to identify astronomical events such as equinoxes and solstices.
“You start watching how nature operates and how that seems to relate to the sun, and at some point, there came a realization that we should do something to commemorate,” Frost said. This commemoration came in the placement of markers and development of ceremonies that corresponded with these events.
The investigation of these ancient practices is known as archaeoastronomy and is one of many pieces to understanding how these ancient peoples lived and how they have influenced those after them.
“What’s important about this whole idea of archaeoastronomy is the Native Americans that lived here, the ancestral Puebloans, they were farmers, so they had to know when to start their calendar year, and it typically started with the winter solstice,” said Jeff Brown, interpretive ranger at Mesa Verde National Park.
Monitoring the passage of seasons is something practiced across the globe by agrarian cultures, particularly the summer solstice, said Pat Hasenbuhler, a tour guide at Chimney Rock National Monument. “In any farming culture, you see them observing June 21 – first day of summer but also usually the first day of planting for the longer growing period of corn.”
At Mesa Verde, the Balcony House site has archaeoastronomy features. A window captures the rays of the rising sun during the equinoxes and casts them on a triangular-shaped stone. On the summer solstice, a single wooden beam extending from the exterior of one house points to the location where the sun rises over Mancos Mesa, said Cristy Brown, public information officer for Mesa Verde.
But while archaeoastronomy is present at Mesa Verde, other sites in the region have more features, Jeff Brown said. “An obvious one is Chaco Culture National Historical Park to the southeast. Archaeoastronomy is all over that place; there is astronomy built into the architecture itself.”
The location known best for its archaeoastronomy connection in Chaco is Fajada Butte, which is located on the southern border of the park in New Mexico.
Here, there are two petroglyph spirals of different sizes and a series of large slabs that cause the sun’s rays to form dagger-like shapes that are cast either through the middle of the spirals or to either side of them on the winter and summer solstices, Jeff Brown said.
Chaco was a center of activity for thousands of people from 800s to 1100s A.D. In 2013, it was designated an International Dark Sky Park.
Chimney Rock, between Durango and Pagosa Springs, has several archaeoastronomy connections, including at the equinoxes and the summer solstice, Hasenbuhler said. Probably the most well-known of which is the Northern Major Lunar Standstill, when the full moon sets between the two spires. The standstill occurs every 18.6 years.
The Great House Pueblo, which was constructed by Chacoan settlers at Chimney Rock, was built for the viewing of this event, he said. “The Chacoan site is positioned in such as way that it is the only place you can really see this happening.”
This connection to the lunar standstill doesn’t point to agrarian practices but perhaps to a cultural connection with the Mayans and Incas of Central America, who also observed and celebrated this phenomenon, Hasenbuhler said. But the exact nature or extent of this connection is still debated among archaeologists.
“Some believe it was a real strong connection, some feel it was just a mild trading connection,” he said.
Sites, such as Balcony House, Fajada Butte and Chimney Rock, generally have their archaeoastronomy connections validated by viewing and documenting the passage of the sun, or moon, on different days of the year and seeing if they align with the architecture in place, but going to a site looking to confirm a hypothesis bears a risk, Frost said.
“We always express there’s caution with it: If you’re looking for it, you’re likely to find it, whatever it is,” she said.
This confirmation bias highlights the need to objectively assess the evidence at the sites, while at the same time accounting for differing interpretations from descendant tribes, she said. The age of the sites and practices of the ancestral Puebloans can at times compound these obstacles.
“An important thing to recall is that this is all prehistoric, before there is any written history,” Frost said. But these ancient practices are still influential on descendant tribes of the ancestral Puebloans.
“They oftentimes still watch the sun and plan ceremonies and feasts around time frames that are related to those equinoxes and solstices,” she said.
In some cases, research and preservation efforts at ancient sites have inadvertently altered architecture and harmed the integrity of astronomical features.
At Casa Riconada in Chaco Culture National Historical Park, there is an occurrence on the equinoxes and solstices where the sun shines through a doorway and hits certain elements in the architecture, Frost said. However, because of efforts to repair the structure by early scholars, it is not known if this was the original intent of the ancestral Puebloans.
“The gentleman who was doing the reconstruction was not paying attention to alignments, and as far as we know, knew nothing about it, and he was trying to reconstruct it based on the evidence found at the location,” she said.
Because of this danger, Chaco and Mesa Verde have to carefully manage sites to maintain their cultural and historical significance.
Fajada Butte is an example of how visitation can harm a site.
In 1999, a documentary highlighted the many astronomical features of Chaco, particularly the sun daggers present at Fajada Butte, Frost said.
This film caused an increase in visitors and researchers to view this occurrence, which was detrimental to the site, Cristy Brown said.
“It created a lot of traffic there, and we ended up having an erosion issue that allowed those slabs to shift. So the few photos, and I believe there’s even a short video, of that occurrence are all we have left,” Frost said. Since then, the National Park Service has made efforts to halt the erosion but not to return the slabs that shifted to their original location.
Another factor is the effect of geological processes at sites throughout the Southwest, Cristy Brown said. Shifting and settling of the earth can change ever so slightly the alignment of architecture to these astronomical phenomenons, ruining the association.
At Chimney Rock, the largest factors in endangering the sites’ viability are weather and erosion over time of the Chacoan building that aligns with astral phenomena, Hasenbuhler said.
With reconstruction efforts viewed as potentially undermining the historical significance of sites, there is little management agencies can do besides preserve and monitor the visitation sites such as Fajada Butte receive.
Fort Lewis College student Luke Perkins was an intern at The Durango Herald this summer. Email him at ldperkins@fortlewis.edu.
