The major lunar standstill
Going forward – and back – in time at Chimney Rock

SideStory: Viewing the standstill

by Amy Maestas

First came Aldeberan, the brightest and alpha star of the constellation of Taurus, flickering faintly in the dark sky and under the din of lights from Pagosa Springs. Though 60 light years away, it seemed to be cozily clinging to spiny Companion Rock.

Moments later Elnath burst through the darkness, creeping in on Aldeberan’s tail. It was hard to miss this red giant star about 40 times the diameter of the sun. Elnath makes up the bull’s left horn.

Then, in dramatic fashion, the moon glided in, the orb smoothly lighting up until a crescent formed. And there it hung, in the balance, framed neatly by Chimney Rock on one side, Companion Rock on the other. The clear night sky, thick with stars, instantly became a theater.

The audience – those few of us standing on a sturdy fire watchtower – remained silent. In awe. Unexpectedly dazzled. This momentary performance was so precise and calculated, a few paces to my left would have given me a different view. A few paces to my right a completely other view. A few more in either direction and you miss it completely. No one shared spaces, making the show that much more remarkable.

Four minutes later, the show was over. It was as if the sacred rock spires drew their curtains for the morning. There wasn’t an encore. The next show – same place, different hour.

Standing still

The moon rises every day. It is the most conspicuous astronomical object in the sky. But on this morning, its performance carried extraordinary meaning that at least regionally is just beginning to make its implications known. As novice lunar observers and this land’s newest inhabitants, we are learning only now what puebloan residents knew thousands of years ago. We use high technology; they used the naked eye.

Yet we both have seen the same phenomenon: a major lunar standstill.

This astronomical occurrence happens only every 18.61 years. That number is precise, just as the moon’s rising position is. The moon undergoes a sequence of illumination every 28 days, following daily and seasonal paths – much like the sun – rising at different places on the horizon. But unlike the sun, the moon’s orbit is about five degrees from the line that connects all the sun’s locations in a year, explain astronomers. This affects the moon’s declination – the distance north or south of the Celestial Equator – and ultimately changes azimuth of the moonrise and moonset. In short, the moon travels a direction, reaches a maximum value, travels south, reaches a maximum value, and so on, over about 18 years’ time. When the moon reaches its maximum declination, it stands still, rising or setting in the same spot for several nights in a row – a “lunar standstill.”

Up until the last major lunar standstill, in 1989, this happening came and went unnoticed at Chimney Rock, although it was being observed at various other monolithic sites around the world. It wasn’t until

this time that a retired University of Colorado-Boulder professor rediscovered, after diligent research, this astronomical event at Chimney Rock.

The 3,160-acre site is the northernmost, highest-elevated puebloan community connected to Chaco Canyon, explains Glenn Raby, Chimney Rock manager.

Raby says archaeologists believe that Chimney Rock was most prominently a religious colony and astronomical observatory. Ancestral Puebloans built their city at these rocks in the 11th century. The Great House, a 55-room structure, is positioned exactly in a spot to witness the standstill.

“Some people think it might have been a VIP house for visitors,” says Raby.

Those VIPs, in modern-day lingo, were likely tribal members from various American Indian groups, whose visits were solely to perform religious rituals. Many tribes in New Mexico have connections to Chimney Rock – Nambe, Pojoaque, San Ildefanso and Taos, to name a few.

Ancient celebrations

Raby explains that the most compelling evidence that Chimney Rock dwellers knew and celebrated this event is based on dendrochronology, the science of tree-ring dating. Studying surviving wood at the site, retired professor McKim Malville determined that the Great House was built in 1026. Another phase of construction – a higher level on the house that may have been intended to provide a better view of the sky, says Raby – took place in 1093.

“Both of those years were times a lunar standstill took place,” Raby explains.

Malville and his team’s research put this sacred archaeological site on the world map. Though such a standstill event is viewable throughout the world, Raby underscores Chimney Rock’s importance because of its innate contribution.

“Of all the places in the Southwestern United States,” he says, “this is the only place where you can observe the standstill just by being here. Other sites had to build something to see this type of thing. But not here.”

As Malville’s research became better known, Chimney Rock and Forest Service managers worked extensively with leaders from regional pueblos, looking to them for historical accounts as well as guidance on exposing this information to the public. The site remains highly sacred today, with many ceremonies staged there.

Raby says we’ll probably never know how great a role the standstill, and astronomy in general, played in decisions to build structures at Chimney Rock. We may never even know the extent of pre-planning it took. One thing is known, though – the amount of planning that the Chimney Rock staff and archaeologists put into studying the standstill over the last 18 years, especially since December. In late winter, Raby and others routinely charted the dates, times and phases of the moon rises, calculating the information to arrive at predictions for standstill events.

“We watched it closely during the winter solstice, and since then we have seen it move closer and closer to the rocks,” he explains. “Based on this information, we are pretty certain of the time and dates of this event.”

Raby also explains that the group took several months to study the event to determine what it entailed. The only contemporary evidence was from Malville’s lone photograph in the late 1980s. Without knowing what the standstill would look like or how the public could participate, Raby chose not to publicize the event until recently.

The popularity of the standstill at this site is growing rapidly. Given the relative newness of the rediscovery, Raby says only a couple hundred people have watched a standstill at Chimney Rock so far. It’s not a once-in-a-lifetime viewing, he adds, but it is indeed rare. Raby also says two film companies have applied for permits to make documentaries of the event and its significance with Chimney Rock. The archaeological area is also working with students, especially from native pueblos, to educate them about the history and significance.

At one point in the wee hours of the morning, Raby states the standstill as plainly as he can: “It’s the moon outdoing the sun.”



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