A window to the sky By Lawrence Spohn

A thousand years later, folks still flock to Chaco Canyon National Park to witness the summer solstice.

They watched the window-shaped beacon of sunlight inch down and across the curved rock wall, mirroring the sun’s path up and across the cobalt sky that draped over the canyon walls. Eventually, the solar beacon rested almost perfectly within a similarly shaped internal cove, or niche, on the wall opposite the window. So began summer solstice 2004 – exactly as it did a thousand years ago here at the height the Chacoan Culture, which reigned from about 850 to 1150.

The window and niche, archaeo-astronomers believe, are among many astronomical markers that the observationally astute Chacoans created to mark the passage of time on a seasonal basis. Archaeologists say the markers – including an impressive, moving sun-dagger of light discovered atop Fajada Butte – likely were used to regulate the ancient Indian society and culture – perhaps everything from religion and civil ceremonies to agricultural practices.

More and more, researchers are discovering evidence in the canyon ruins that suggest Chacoans built their muti-room, multi-story buildings – one the size of the ancient Roman Coliseum – along lines traced through the canyon by the seasonal passages of the sun and moon. While much remains speculative, some scientists argue proof is mounting that the elaborate astronomical design was implemented over centuries, suggesting an extensive and provocative, long-term architectural master plan.