Almost 7,500 years ago, around the year 5446 BCE by modern calendars, a star exploded, sending incredibly bright light out into space. The light from that supernova reached Earth on July 4, 1054. Chinese astronomers recorded a bright new star that suddenly appeared in the sky. It was so bright that it was visible both day and night for months.

Halfway around the world, Chaco was near the height of its power, a ceremonial and administrative city and center of trade whose grandeur was unmatched in the Ancestral Puebloan world. A culture deeply attuned to the cosmos—multiple structures at Chaco were oriented to the solstices and equinoxes—the Chacoans would have born witness to the new star. It is possible that they recorded the supernova—now faded into what modern astronomers know as the Crab Nebula in the constellation Taurus—on a remarkable pictograph panel near the western end of Chaco Canyon.

Continuing our day in Chaco Canyon on May 20 [2022], Sean and I determined to hike to see the Supernova Pictograph.

It was about half past eleven when we departed Pueblo Bonito and continued along the loop road the short distance to the Peñasco Blanco (Spanish for “White Cliff”) Trailhead parking area.

Although we were still full from our breakfast burritos, we each had a banana to give us some energy for the six-mile out-and-back hike. The trail was basically flat, and we would be passing two small Great Houses and dozens of petroglyphs on the way to the Supernova Pictograph. We set out, trending northwest down the canyon.

The first of the two Great Houses is right near the start of the trail.

Construction on Kin Kletso (Navajo for “Yellow House”) started around 1100 CE in the last great construction period before Chaco was abandoned.

The masonry style used at Kin Kletso was different than earlier Chacoan styles. Known as “McElmo Style” for its origins in and around McElmo Creek and Canyon, it replicated the style used in Montezuma Valley below Mesa Verde. Montezuma Valley was densely populated in the later Chacoan period, even more populated than it is today. Apparently building techniques that originated in a vibrant population center far from the Ancestral Puebloan capital in turn influenced the grand ceremonial city.

McElmo Style at Kin Kletso used masonry formed from larger, blockier sandstone bricks than the delicately formed slabs of earlier Chacoan structures.

During our hike, the temperature was in the mid-70s. We both remarked that we would not have wanted to do the hike in weather that was any hotter.

It’s likely that drought was the underlying factor that led to the fall of Chaco around 1150 and started a transformation of the Ancestral Puebloan world. The understanding of archaeologists is that twentieth century climate conditions were largely similar to ninth century conditions, when Chaco began its rapid development from small villages to Great Houses.

On our hike, seeing the atmospheric dust and thinking about the wildfires in the Jemez and Sangre de Cristo Mountains to the east and the omnipresent drought in the West, it was hard not to feel apocalyptic , as if we were getting a sense of what may have led to the collapse of this place.

Our experience may even have been worse than that of the Chacoans since decades of overgrazing in the canyon has destroyed it ecologically. As in so much of the West, native grasses were lost to livestock, causing the topsoil to blow away. Without plants to hold Chaco Wash’s banks in place, it has become deeply and unnaturally channelized. Invasive tamarisk outcompetes other plants along the wash, making the ecological ruin even more pronounced.

Farther along the trail, we arrived at Casa Chiquita (Spanish for “Little House”), which seemed almost to emerge from the northern wall of Chaco Canyon. Casa Chiquita also dates from the final period of Chaco construction, and it was also built in McElmo Style.

Shortly beyond Casa Chiquita we began noticing our first petroglyphs.

Sometimes petroglyph panels can be hard to see at first.

Your eyes play tricks. What is natural discoloration in the sandstone and what is a petroglyph?

But once you spot them, they leap out.

A little farther along, we reached “Petroglyph Trail,” a side trail that parallels the main trail and hugs the bottom of the cliff as it winds past the largest concentration of petroglyphs at Chaco.

Before turning our attention to the cliffs, we spotted the walls of Peñasco Blanco rising from the mesa across the canyon.

Then we turned to the petroglyphs.

Generally, the deeply incised, and therefore brighter, petroglyphs were Ancestral Puebloan, presumably Chacoan, although exact dating of petroglyphs is nearly impossible. The panel above also includes fainter, later Navajo petroglyphs. The major tell, aside from the difference in style, is that the Navajo petroglyph includes a horse, dating it definitively after the arrival of the Spanish in North America.

Farther along, separate from the other panels, was a trio of figures thirty-five feet up the cliff face.

The more abstract image with the Bighorn Sheep and the (apparently male) supernatural figure is a katsina mask, pointing toward the rise of kachinas in post-Chacoan Pueblo religious traditions.

Back at ground level there were clusters and individual images here and there. The contemporary feeling horse in the panel above was made by a nearby Navajo resident around 1940.

We also noted a few more modern scratches like the cross above.

Near the western end of the petroglyph cliffs, the final panel included dozens of nineteenth and twentieth century Anglo incisions and scratches.

Here Hopi and Pueblo Indian descendants often recognize the Chacoan images as meaningful symbols. Some petroglyphs represent clan symbols and affirm ancient and ongoing associations to Chaco. They mark the paths of clans’ sacred migrations.

– Backcountry Trail Guide

After rejoining the main trail, we still had 1.2 miles to go to reach the Supernova Pictograph. I love that this sign just says “SUPERNOVA.”

The trail left the north wall and began crossing the canyon floor on a diagonal.

Sean was surprised that the supernova pictograph was on the other side of the canyon. So much of the most important cultural elements we’d seen were on the north side.

We crossed Chaco Wash near the southern wall.

There were a few more petroglyph panels as we approached the pictographs.

And then there it was, right above us.

Two of the images are easily recognizable:

The crescent moon.

And a human hand.

The third, a ten-pointed star with a slight sense of clockwise motion, is the Supernova Pictograph, a representation of the explosion that created the Crab Nebula.

What must it have meant to a culture at that height of its power and influence, which was profoundly tuned to astronomy, for a new star bright enough to overcome daylight to suddenly appear? And what did it mean to place a human hand—a widespread motif in Ancestral Puebloan rock art often thought to mean “we are/were here”—among these celestial depictions?

But there’s more.

Look closely. There is a fourth pictograph in the grouping, located on the the vertical rock face, fainter than the others, likely because of more direct exposure to light.

To the left is a closed circle within two progressively larger rings.

Stretching out to the right from the circles is a jagged wash of pigment that looks like fire.

Or perhaps the tail of a comet.

Eleven years after the appearance of the supernova, in 1066 CE, Halley’s Comet appeared in night sky. It is possible that this is a depiction of Halley’s Comet. If so, it rivals the “earliest known depiction of Halley’s Comet”: in the Bayeux Tapestry.

After contemplating the cosmos, we turned away from the wall and faced our dusty walk back. It was ten minutes to one, so we decided not to hike up onto the mesa to see Peñasco Blanco. There were other sights we didn’t want to miss in “Downtown Chaco.” And we were ready for lunch.

There had been very few other people on the trail. On the way out, we’d only seen a few folks at the petroglyphs. We were completely alone between the petroglyphs and the Supernova Pictograph and back. Now as we approached the trailhead things picked up including a man on a motorized bicycle (which was definitely not allowed) and a group of women walking huskies, of all dogs. They all felt out of place in the landscape.

It took us less than an hour to hike back since we bypassed the petroglyphs.

Back at the trailhead, we ate our sandwiches and contemplated the canyon at a picnic table under a shelter.

Then it was time to stroll around “Downtown Chaco.”