by Kim Malville

Three bright planets are visible in the evening skies. The two brightest are Jupiter in Leo and Mars in Libra. Saturn is a little fainter, appearing to the east in Scorpio. 

June 17: The Moon, Saturn, and Mars will form a wide triangle. The Moon will be above Antares, the red heart of the Scorpion.

June 20: Summer solstice in the northern hemisphere. The longest day of the year occurs at 4:43pm MDT.

Explore the astronomy of Chimney Rock

If you haven’t done this already, consider a trip this summer to explore the astronomy of some of the ruins of the ancestral pueblos of Colorado at Chimney Rock. It is a drive of 2 hours to Pagosa Springs and another half hour to the Chimney Rock visitors’ center.  It is certainly the most dramatically located ruin in the Southwest. Perhaps you may even have puzzled over it, driving between Pagosa Springs and Durango. It is certainly worth a visit. You can reserve space on a tour through their website, . There is a special early morning trip on June solstice, for which reservations are needed. One can camp at the Ute Campground nearby. 

My experiences at Chimney Rock started nearly 28 years ago when I was leading a two-month field school in archaeoastronomy at Yellow Jacket, north of Cortez. Professor Frank Eddy, one of my colleagues at CU, who had excavated Chimney Rock in 1970-2, had suggested to me that the high mesa at Chimney Rock looked and felt like an observatory, high above the surrounding countryside. 

The Chimney Rock Pueblo, a Chacoan-like two-story Great House, had been constructed on the mesa just below the two rock towers. It was an unlikely place for a building, a two-story structure with perhaps 35 rooms and two kivas, on such a remove location. It was 1500 feet above the Piedra River, far from water or agricultural lands. It could be approached only by a narrow causeway, over which all the building materials had to be carried.

When I was planning for research programs that summer, I consulted the topographic map of the area and noted that the orientation of the mesa is approximately along the line toward sunrise on summer solstice. My first guess was that the Great House had been constructed in such an unlikely place because it provided a view of summer solstice sunrise between the double chimneys. Could that have been sufficient justification? With that possibility in mind, I climbed up to the upper mesa at dawn of June 21. To my disappointment I found that sunrise was well to the south of the chimneys.  At least it was a hypothesis that was easy disprove!

During that summer I continued to wonder what kind of astronomy might be associated with those majestic rock towers. I knew Venus sometime rises slightly to the north of the sun at solstice, but after checking out its orbit I found that it could not rise in the gap as seen from the Chimney Rock Pueblo.

By the end of July our team had surveyed the outline of the chimneys, and I knew the necessary coordinates for an astronomical object to fit between the chimneys. I checked out the moon and discovered that at its most northern rising position, known as northern major standstill, the moon just might fit between the towers. The major standstill only happens every 18.6 years, and by a wonderful bit of good luck the moon was nearing the end of its major standstill period. I figured that—just possibly—on the early morning hours of August 8, the moon might rise between the towers. My students were justifiably skeptical that it would be worth staying up until two in the morning on that high mesa based on my calculations. I joked with them that Chinese astronomers often lost their heads when wrong, and I swore them to secrecy, just in case my calculations didn’t work out. By one in the morning they were increasingly skeptical and getting a little rebellious. Fortunately the moon behaved beautifully. Everyone was stunned and nicely impressed. The moon came up as predicted, we captured its spectacular rise on film. I may not have been believed without such evidence.

The next time the rising moon was photographed between the chimneys was in the fall of 2004, some 16 years later. Chimney Rock may be the only place in the world where natural topography so beautifully frames the moon at its major standstill. The appearances of the moon between the chimneys would have been impressive events for those who lived there. The Chimney Rock Pueblo had been originally built in 1076 and then rebuilt in 1093. Both of these dates were times of major standstill of the moon. For some reason the area was abandoned soon after that last moonrise.

Over the next few years we discovered three locations for watching the sun to come up at summer solstice. Chimney Rock was indeed beginning to look like an observatory. The Forest Service took note and began emphasizing the astronomy of the place. The moon returned in 2004 and for three years, once a month, it rose between the chimneys. The Forest Service organized tours at night to watch the spectacle, charging $50 per person.

A fire tower had been built next to the Great House in the 1930s, unfortunately blocking a direct view of moonrises from the Great House. In 2010, quite wonderfully, the Forest Service removed the fire tower, allowing an unimpeded view of moonrise from the Great House. Best of all, partly because of its astronomy, the area became a National Monument on September 21, 2012. A devoted and talented group of volunteers runs tours throughout the summer. Give them a try this summer. Afterward, consider stopping at the Pagosa Brewery for a sip of Ancestral Ale, specially brewed for the inauguration of the National Monument. You will note the label shows moonrise between the chimneys.