by Kim Malville

September 1: Look to the southwest about 45 minutes after sunset. Jupiter will be close to the horizon and Spica will be below it. Above, some 20 degrees away, will be brilliant Arcturus.

September 6: Full moon

September 11: Just after sunset look for Jupiter and Spica close together.

September 22: Equinox at 2:02 MDT. Look for a shin crescent moon after sunset above Jupiter.

September 26: The moon will be above Saturn.


Coronal mass ejection (CME) from space.

Coronal mass ejection (CME) from space. 
photo courtesy of NASA


Ancient people may have seen a solar eclipse as inspiring, not frightening 

Millions of people gazed at the great American eclipse this August 21, shooting photographs and taking selfies. A thousand years ago, early Pueblo people living in Chaco Canyon may have captured their experience with a total solar eclipse by creating a petroglyph consisting of a circle with looping streamers that resemble the sun’s outer atmosphere, or corona.

Not only may the petroglyph depict a solar eclipse, but they may also have watched the sun undergoing an eruption of plasma called a coronal mass ejection (CME). Many scholars have claimed that eclipses were understood to be ominous omens in the past.  For instance, in Babylon, astrologers warned that a king might die during an eclipse. To prevent that from happening, a king would be replaced by a commoner for a few days around the time of the eclipse. Once the danger had passed, the king would be returned to the throne.  There was reportedly one occasion when the king died when accidentally drinking something that was too hot, and the commoner continued as king.

I’m not convinced that everyone in the past experienced eclipses as fearsome. The sun does go out, to be sure, and some may have feared that it would never return. Others may have been concerned about a diminishing of the sun’s power. But, for those who stayed outside and looked closely at the pearly white corona with its intricate filaments, the view should have been glorious.

Possible petroglyph depicting the total eclipse of 1097 with a coronal mass ejection in progress.

Possible petroglyph depicting the total eclipse of 1097 with a coronal mass ejection in progress.
photo by Kim Malville

If indeed the petroglyph in Chaco depicts an eclipse, the experience may have been more celebratory than frightening. That eclipse lasted a little more than 4 minutes, and someone may have remained outside during the eclipse, not closing their eyes, turning their back on the sun, or running inside. Perhaps they initially sketched the sight with charcoal on the rock face. They may have made a record to depict the extraordinary sight of the corona, like nothing they had seen. This was the only eclipse to cross Chaco Canyon during the height of the Chaco culture, and they viewed for the first time another feature of the all-powerful sun, perhaps understood as a living being who was even more mysterious than they imagined.

I first saw the petroglyph in 1992, while leading a field school on archaeoastronomy with Jim Judge, then a professor of anthropology at Fort Lewis College. It seemed strangely familiar.

Some people might see it as a tick or a spider, but to a solar astronomer it struck me as similar to photographs of coronal mass ejections which, when they hit the earth, produce auroral displays, magnetic storms, and disruption of electrical networks. That was some 25 years ago. Over the years, the petroglyph has generated mild interest. I discussed it at several meetings, published it in my book on prehistoric astronomy of the southwest, but it must have seemed arcane and academic, unrelated to anything in today’s world.  Now, this modest petroglyph is getting lots of attention.

In 2014, Professor José Vaquero of the University of Extremadura in Cáceres, Spain collaborated with me in analyzing the petroglyph. We knew that an eclipse had occurred that was visible in Chaco Canyon on July 11, 1097, but what was the possibility that the sun was active and producing CMEs around that time? We investigated other surrogate indicators of solar activity, such as days during the year when an aurora was visible in northern Europe, detection of large sunspots, and the amount of carbon 14 in tree rings. Each of these pointed to high levels of activity on the sun in 1097. We presented these results in a conference in Athens and wrote them up for the Journal of Mediterranean Archaeology and Archaeometry, published by the University of the Aegean in Rhodes.


Piedra del Sol as seen from the east.

Piedra del Sol as seen from the east. photo by Kim Malville

If our interpretation is correct, the careful depiction of the eclipse suggest the observers considered it to be celebratory rather than frightening, something beautiful instead of catastrophic. We experienced such a celebratory eclipse on June 30, 1973, in Kenya, when we camped at the eastern edge of Lake Turkana among Turkana, Samburu, and El Molo tribes. This particular eclipse lasted seven minutes, an unusually long time, and the locals had a chance to see the beauty of the corona during totality. Afterward, the tribes visited our camp for the first time and performed dances to celebrate the eclipse and to thank us. The Kenya government had been concerned about our safety, but there was no need. After the dances, we introduced them to the party game of stepping through broomsticks, substituting spears for broomsticks. All of us ended up falling on the ground as we tried to step through the spears. These stern warriors with their razor-sharp spears, whom we feared as we walked past them on our way to our telescopes, became laughing players in our games.

I suspect that the 1097 eclipse in Chaco Canyon may have stirred a similar appreciation of the beauty of an eclipse in the residents of Chaco Canyon. After 1100, the people built ten so-called Great Houses, (such as Wijiji and Kin Kletso) which are located at spots that provide dramatic views of the rising or setting sun at winter or summer solstice. There is the possibility that the glory of that experience for the people living in Chaco in 1097 resulted in an increased reverence for the sun and a religious revival evidenced by the careful placing of these new Great Houses.