Ancient Indigenous Americans were accomplished astronomers. They created ceremonial calendars, planned when to farm and hunt, and told origin stories all based on their keen observation of the skies above.
The grand complex at Chaco Canyon reveals the ancestral Puebloans' vast knowledge of the planets, stars and other celestial objects. Built over hundreds of years (beginning around AD 850) in the high desert of northwestern New Mexico, its massive stone buildings or great houses – which reached up to four stories high and contained hundreds of rooms – were all designed in relationship to the sun, moon and four cardinal directions. Large ceremonial kivas and observational sites found throughout the canyon also reflect their understanding of the celestial role in seasonal cycles here on Earth.
The most famous of these sites is a set of spiral petroglyphs, discovered behind three giant rock slabs high atop Fajada Butte at the canyon's southern entrance. This “Sun Dagger” exactly marks the summer and winter solstices, as well as the spring and fall equinoxes.
While mysteries still swirl around Chaco, it clearly was a major cosmological and ceremonial center that brought people together from across the American Southwest. An extensive network of roads connected the complex to more than 150 great houses throughout the region. This Hopi origin story speaks to the importance of Chaco Canyon and why it is considered sacred to Native Americans.
Although abandoned around AD 1150, Chaco Canyon continues to enthrall stargazers with its clear, dark nighttime skies that remain unpolluted with city lights. Chaco Culture National Historical Park – a UNESCO World Heritage site – was officially designated as an International Dark Sky Park in 2013. It is the only U.S. national park to feature its own observatory, where you can ponder the same star-studded skies that the Chacoans did a thousand years ago.
"The Mystery of Chaco Canyon," narrated by Robert Redford, is a fascinating documentary about the Solstice Project's ongoing study of ancient Chaco culture and its rich astronomical heritage. You can watch it on Amazon Prime or the project's website.
Additional resource: https://www.nps.gov/chcu/index.htm