In the late spring of the year AD 1006, a bright supernova appeared in the southern constellation of Lupus. The event is found in astronomical records from east Asia as well as Europe and the Middle East, yet thus far there is no rock art record of the event from North America.
In 1993 while on a day trip to a petroglyph site in the White Tank Mountains Regional Park west of Phoenix, AZ, I came across a particular set of glyphs which may represent an eyewitness record of the event. 11 archeological sites occupied during 500-1100 CE, have been found in the park.
They are associated with the Hohokam culture that existed in what is now southern Arizona and norther Sonora, Mexico, between about 300 and 1500 CE. There is some evidence that the modern Akimel and Tohono Oʼodham people are their modern descendants. The Hohokam seem to have been keen skywatchers. According to Bostwick (2014), "Several locations are identified in the Phoenix region of Arizona, including mountains and prominent rock formations, where the solstices and equinoxes could be tracked through horizon alignments during sunrise and sunset and by light-and-shadow patterns during midday on those solar events." There are also suggestions that the surviving Hohokam structure at Casa Grande Ruins National Monument served in part as a sophisticated astronomical observatory.
In 1993 while on a day trip to a petroglyph site in the White Tank Mountains Regional Park west of Phoenix, AZ, I came across a particular set of glyphs which may represent an eyewitness record of the event. 11 archeological sites occupied during 500-1100 CE, have been found in the park.
They are associated with the Hohokam culture that existed in what is now southern Arizona and norther Sonora, Mexico, between about 300 and 1500 CE. There is some evidence that the modern Akimel and Tohono Oʼodham people are their modern descendants. The Hohokam seem to have been keen skywatchers. According to Bostwick (2014), "Several locations are identified in the Phoenix region of Arizona, including mountains and prominent rock formations, where the solstices and equinoxes could be tracked through horizon alignments during sunrise and sunset and by light-and-shadow patterns during midday on those solar events." There are also suggestions that the surviving Hohokam structure at Casa Grande Ruins National Monument served in part as a sophisticated astronomical observatory.
Here's the original image, scanned from a photographic print:
Comparison with a 2006 the same rock shows little evidence for alteration by defacing in the intervening 13 years:
This is my tracing of the glyphs on the rocks highlighting several distinct figures:
The aspect of this rock art panel that caught my attention was the figure at upper left, which resembles other Hohokam glyphs thought to represent scorpions. It is an oriented figure facing right with what appear to be chelae (hinged pincer-like claws), legs, and a tail. These are creatures with which the desert-dwelling Hohokam would have been very familiar.
To the right of this figure, near the center of the panel, is a glyph resembling many other Hohokam glyphs representing stars or other bright objects in the sky. Below and between them is a glyph often interpreted as the Sun (a roundish object with an empty center surrounded by many rays).
The juxtaposition of figures that could plausibly be interpreted as a scorpion and bright sky object, in their relative positions, immediately reminded me of the positions of the classical constellation Scorpius and the bright supernova recorded by European and Chinese astronomers that first appeared in the night sky in the early hours of 1 May 1006 CE. The object would have been visible from the location of the petroglyph, rising some 20 degrees above the southern horizon just before midnight. With a peak visual brightness of magnitude -7.5, it outshone every other object in the night sky. For the inhabitants of the area, it would have been an unforgettable sight.
Another important aspect of the rock panel that may help us understand its meaning is the crack running mostly left-to-right for more than half its width. Long before the figures on it were carved, a process called "spalling" removed some of its material. Hot-cold cycles over eons worked open small cracks that became bigger. Eventually part of the rock sloughs off the surface, exposing fresh material underneath. Given that the material below the crack is nearly as dark as that above it — both surfaces being darkened by a biomineral coating known as desert varnish — we know this must have happened very long ago.
Prehistoric Native American rock artists often incorporated naturally occurring aspects of rocks into their designs. Here, the crack bears at least a superficial resemblance to the profile of the mountain ridge to the immediate south of the petroglyph site:
To the right of this figure, near the center of the panel, is a glyph resembling many other Hohokam glyphs representing stars or other bright objects in the sky. Below and between them is a glyph often interpreted as the Sun (a roundish object with an empty center surrounded by many rays).
The juxtaposition of figures that could plausibly be interpreted as a scorpion and bright sky object, in their relative positions, immediately reminded me of the positions of the classical constellation Scorpius and the bright supernova recorded by European and Chinese astronomers that first appeared in the night sky in the early hours of 1 May 1006 CE. The object would have been visible from the location of the petroglyph, rising some 20 degrees above the southern horizon just before midnight. With a peak visual brightness of magnitude -7.5, it outshone every other object in the night sky. For the inhabitants of the area, it would have been an unforgettable sight.
Another important aspect of the rock panel that may help us understand its meaning is the crack running mostly left-to-right for more than half its width. Long before the figures on it were carved, a process called "spalling" removed some of its material. Hot-cold cycles over eons worked open small cracks that became bigger. Eventually part of the rock sloughs off the surface, exposing fresh material underneath. Given that the material below the crack is nearly as dark as that above it — both surfaces being darkened by a biomineral coating known as desert varnish — we know this must have happened very long ago.
Prehistoric Native American rock artists often incorporated naturally occurring aspects of rocks into their designs. Here, the crack bears at least a superficial resemblance to the profile of the mountain ridge to the immediate south of the petroglyph site:
Noticing this, I began to suspect that the arrangement could represent an eyewitness depiction of the situation from the perspective of the rock art panel.
So how well does this match what skywatchers in ancient Arizona would have actually seen? To figure that out, on my 2006 visit to the site I obtained a 360-degree panoramic photomosaic of the view from the position of the petroglyph. Using photogrammetry, I determined where the local horizon line was and then lined up the photomosaic with the cardinal directions. The result was merged with a planetarium simulation of the night sky from that location on the night the supernova first appeared, to which is added a visual affect representing the apparent brightness and known location of the supernova on the night sky:
So how well does this match what skywatchers in ancient Arizona would have actually seen? To figure that out, on my 2006 visit to the site I obtained a 360-degree panoramic photomosaic of the view from the position of the petroglyph. Using photogrammetry, I determined where the local horizon line was and then lined up the photomosaic with the cardinal directions. The result was merged with a planetarium simulation of the night sky from that location on the night the supernova first appeared, to which is added a visual affect representing the apparent brightness and known location of the supernova on the night sky:
This final result replaces the generic horizon of the planetarium simulation with the actual horizon of the rock art panel site:
Now compare this to the picture of the rock art panel above. There are some things I notice; for example, with a little imagination, you can make a small birdlike figure out of the stars in eastern Centaurus that resembles the figure below and to the right of the star. Is this therefore a depiction of the Hohokam sky map for this part of the sky?
What I learned from this exercise is that, at the position of the rock on which the glyph is carved, SN 1006 would only have been visible for about an hour each night as it crested the ridge to the south.
Another important question is: Is this depiction of what appears to be a scorpion at all consistent with a constellation meaning? If the "star" near the center is meant to be a starlike object in intended meaning, could the scorpion indicate a relative position in the sky to the constellation we now call Scorpius? It's not an unreasonable proposition since many ancient cultures, Western and non-Western, identified the asterism we call the constellation Scorpius with either actual scorpions or dragons. Among pre-contact cultures of the Americas, for example, the Maya saw the stars of the Greek constellation Scorpius as Pa Raqan Kej, the Scorpion; for references, see Salanic (2021) and Josh Sokol's 2022 Science article "The Stargazers". The Hohokam had trade ties with Mesoamerican cultures, but we do not know the extent to which they were influenced by the cosmology of other peoples.
What I learned from this exercise is that, at the position of the rock on which the glyph is carved, SN 1006 would only have been visible for about an hour each night as it crested the ridge to the south.
Another important question is: Is this depiction of what appears to be a scorpion at all consistent with a constellation meaning? If the "star" near the center is meant to be a starlike object in intended meaning, could the scorpion indicate a relative position in the sky to the constellation we now call Scorpius? It's not an unreasonable proposition since many ancient cultures, Western and non-Western, identified the asterism we call the constellation Scorpius with either actual scorpions or dragons. Among pre-contact cultures of the Americas, for example, the Maya saw the stars of the Greek constellation Scorpius as Pa Raqan Kej, the Scorpion; for references, see Salanic (2021) and Josh Sokol's 2022 Science article "The Stargazers". The Hohokam had trade ties with Mesoamerican cultures, but we do not know the extent to which they were influenced by the cosmology of other peoples.