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The Fajada Butte Sun Dagger in Chaco Canyon in New Mexico is a spiral petroglyph that is lit up with brilliant streaks of focused Sunlight at key moments in the year.	Source: YouTube screenshot / Mystery History

Connecting Heaven and Earth: The Sun Dagger of Fajada Butte, New Mexico


Near the entrance to Chaco Canyon, New Mexico, USA is an imposing butte that had sacred significance to the ancestral Pueblo culture, who inhabited Chaco Canyon up until about 1150 AD. On Fajada Butte, behind three stone slabs, are petroglyphs that were used to capture the yearly motion of the Sun, and possibly the Moon. The site is known as the Sun Dagger, because of how Sunlight forms the image of a dagger going directly through the middle of the spiral during the summer solstice. The Sun Dagger was sacred to the people of Chaco Canyon, who would make regular pilgrimages to the site. It also illustrates the role that astronomy played in the ancient Chacoan religion and society.

The Chaco Canyon Fajada Butte Sun Dagger “Clock”

Atop Fajada Butte, behind three stone slabs, are two spirals that were carved into the rock. There is a large spiral, 34 cm by 41 cm (13.4-16.1 inches), and a smaller spiral off to the upper left. Light and shadows penetrating through the gaps in the slabs interact with the spirals throughout the year, but they form special patterns at certain times of the year. Most archaeoastronomers and indigenous informants believe this “clock” to be evidence for intentional alignment with the annual motion of the Sun.

On the summer solstice, in late morning, the Sun shining around the slabs will create a spot of light directly above the large spiral. Over the next fifteen minutes, this point of light will stretch into a shaft of light, or a “dagger,” that goes right through the middle of the spiral. After appearing in the middle of the spiral, the dagger will gradually move down from the spiral and disappear. The entire process from the appearance of the spot of light to the disappearance of the dagger is about 20 minutes.

The light of the Sun on the Fajada Butte Sun Dagger at key times in the annual cycles. (Nationalparks / Public domain)

The light of the Sun on the Fajada Butte Sun Dagger at key times in the annual cycles. (Nationalparks / Public domain)

Something similar happens during the winter solstice. Two points of light will appear on either side of the spiral. Over the course of the next half-hour, the points of light will become shafts of light bracketing the spiral. During the equinoxes, an off-center shaft of light cuts across the large spiral, but another shaft passes directly through the middle of the smaller spiral.

The Fajada Butte Sun Dagger in Chaco Canyon in New Mexico is a spiral petroglyph that is lit up with brilliant streaks of focused Sunlight at key moments in the year. (YouTube screenshot / Mystery History)

The Fajada Butte Sun Dagger in Chaco Canyon in New Mexico is a spiral petroglyph that is lit up with brilliant streaks of focused Sunlight at key moments in the year. (YouTube screenshot / Mystery History)

Relation to Chimney Rock and the Lunar Cycle

In addition to reflecting the annual motion of the Sun, it is possible that the Sun Dagger on Fajada Butte is also meant to capture the periodic motion of the Moon. Fajada Butte may be related to another site located about 140 km (87 miles) away. Chimney Rock is a geologic formation consisting of two natural pinnacles of rock which rise imposingly above the landscape. During the time that the Chacoan culture flourished, the 9th-12th centuries, a prominent ancestral Puebloan community existed nearby. It is possible that the reason for the presence of this community was because they considered the pinnacles of Chimney Rock to be sacred. Modern Puebloan sources say that Chimney rock is associated with the Twin War Gods of Puebloan mythology.

The Chaco culture may have also used the Chimney Rock formation to track the Moon. (Chimney Rock National Monument)

The Chaco culture may have also used the Chimney Rock formation to track the Moon. (Chimney Rock National Monument)

Another reason Chimney Rock might have been culturally important is because of patterns related to an 18.6-year lunar cycle, caused by the precession of the Moon’s orbital plane around Earth due to the Sun’s gravity. Just as the Sun will rise and set farther north or farther south along the horizon depending on the time of year, the Moon will also rise and set farther south or farther north depending on where it is in its 18.6-year cycle.

When the winter solstice was near the rising of the next full Moon during a significant point in this 18.6-year cycle, Chacoan priests may have used this to re-sync the solar and lunar cycles that composed their calendar. The event where the Moon reaches its maximum or minimum declination of rising or setting during the 18.6-year lunar cycle is referred to as a standstill. The Moon rising between the pinnacles of Chimney Rock during standstill would have been a conspicuous marker for where the Moon was in its 18.6-year cycle.

Another important cycle that may have been known to the people of Chaco Canyon is the Metonic cycle, a cycle discovered by the Greek astronomer Meton around 432 BC. Meton based this cycle on the fact that 235 synodic months correspond to 19 solar years. He is believed to have prescribed rules for inserting intercalary months during certain years, over a 19-year period, to keep the ancient Greek luni-solar calendar in sync with the solar year. This is because 12 lunar months of 29 to 30 days is only 354 days while the solar year is about 365.25 days.

Because of this discrepancy between the lunar phase cycle and the solar seasonal cycle, a calendar based on lunar months will fall out of sync with the solar year over time so that the months will no longer correspond with the seasons. For this reason, a thirteenth month, or intercalary month, would need to be occasionally inserted to bring the lunar and solar components of the calendar back into agreement.

It is possible that the ancestral Pueblo did the same with their calendar, explaining why certain sites in Chaco Canyon including Chimney Rock and possibly Fajada Butte seem to capture the motion of the Moon as well as the Sun. Both solar and lunar cycles would need to be known if the Chacoan calendar was luni-solar.

At Fajada Butte, it has been demonstrated that the slabs will cast shadows that cover the spirals in specific ways during standstill events. It is possible that the Sun Dagger was also meant to mark lunar standstill events and used to re-sync the lunar and seasonal cycles captured by the ancient luni-solar calendar of the ancestral Pueblo.

Pueblo Bonito is the of the largest Great Houses at Chaco Canyon. (Viktor Posnov / Adobe Stock)

Pueblo Bonito is the of the largest Great Houses at Chaco Canyon. (Viktor Posnov / Adobe Stock)

Sun Dagger in the Broader Chacoan Cultural Context

Evidence of Chaco Canyon being inhabited dates to about 2900 BC. Around 200 AD there is evidence that the people of Chaco Canyon adopted farming. By 850 AD the inhabitants of Chaco Canyon began to construct large ceremonial structures, such as the Great Houses. The Great Houses were as tall as four to five stories with as many as seven hundred rooms and several kivas.

These structures also appear to have been built with astronomically significant alignments in mind. The Great Houses were connected to a larger ritual landscape, which included places such as Fajada Butte and Chimney Rock.

Another example of this ritual landscape is the Great North Road which is associated with the central complex in Chaco Canyon and celestial north. The road is also associated with a canyon to the north which it crosses, going straight down the steepest cliff of the canyon.

The Chacoan culture flourished until about 1150 AD, when a drought appears to have led to the abandonment of the settlements across the region.

Chaco Canyon is a high desert environment, very dry with scorching hot summers and bitterly cold winters. Despite these harsh conditions, people lived in the region for thousands of years and even built a proto-civilization. It is not clear why the people of Chaco Canyon chose to build their civilization there. One way in which their civilization benefited from the environment of Chaco Canyon, however, was the clear skies that allowed them to conduct precise astronomical observations.

Part of the reason for their interest in astronomy may have been to construct a calendar. After 200 AD, when agriculture arrived in Chaco Canyon, there would have been a greater need to mark the seasons so that farmers would know when to plant and harvest. Knowledge of the cycles of lunar and solar motion throughout the year would have facilitated the marking of the seasons. Over time, these lunar and solar cycles may have gained ritual and ceremonial significance as well and were incorporated into the spiritual and religious beliefs of the people of Chaco Canyon.

This 11th century pictograph at Chaco Canyon may depict the supernova of 1054 AD. This supernova and the Moon were in this configuration when the supernova was near its brightest. An imprint of a hand at the top signifies that this is a sacred place. (Alex Marentes / CC BY-SA 2.0)

The Sun Dagger and Chacoan Cosmology and Religion

A largescale ritual landscape created by monuments built along celestial alignments suggests that the Chacoan culture was unified by common beliefs about the cosmos. They seem to have believed that their everyday lives were deeply connected to the drama of celestial motion. The Sun Dagger may have behaved as a connection between the land and the sky, a contact point between different parts of the Puebloan universe.

It is reported by modern Puebloan sources that pilgrims would go to the Sun Dagger to pray, to make observations, and to leave offerings. These smaller ceremonies at the Sun Dagger were a microcosm of the larger ceremonies that would happen at the Great Houses.

Not much is known of how the ancestral Pueblo themselves understood the astronomical alignments, except from what is known from modern peoples descended from the ancestral Pueblo, such as the Hopi and the Zunis.

The ancestral Pueblo are said to have seen the Sun and the Moon as living spiritual beings. The interaction between the Sun and the Moon during the winter solstice, for example, was understood in terms of the woman in the Moon convincing the Sun to turn back from its southward journey. For another example of Pueblo tradition related to the winter solstice, the Hopi practiced a festival on the winter solstice, Soyal, in which prayer sticks were placed on a Sun altar to turn back the southward motion of the Sun. The festival was succeeded by several ceremonies which involved planting beans and then corn in the kivas as a symbolic anticipation of the planting which would occur in the coming months. It is possible that the Ancestral Pueblo of Chaco Canyon may have had similar ceremonies linking everyday life on Earth to the heavens above.

Sun Dagger Today

In 1989, archaeologists noticed that erosion caused by visitors had shifted the slabs and distorted the alignments. The “dagger” on the summer solstice now appeared thicker and slightly to the left of the center of the spiral before it moved downward. The winter solstice alignment was also significantly deformed from its original configuration. After this discovery, Fajada Butte was closed to visitors and is now open only to yearly inspections of the site by authorized personnel.

Despite these changes, Fajada Butte still is a remnant of the ancient culture of Chaco Canyon. It reveals a culture that was scientifically advanced enough to make precise observations of the Sun and the Moon and possibly the planets as well. It also reveals a culture that saw a deep connection between astronomical cycles and their everyday lives.

Archaeoastronomy reveals how cosmic events that do not directly influence Earth’s environment or ecosphere can have a surprising influence on the course of history and cultural evolution. An eclipse, for example, does little to physically affect the planetary environment of Earth, but because of how humans interpret the eclipse and imagine its meaning, it can significantly influence human societies. To a culture attuned enough to the night sky, it could even precipitate the toppling of a current government if it is interpreted as a sign of the gods’ displeasure. 

Modern Western civilization does not believe itself to be connected to the universe in the same way that the ancestral Pueblo did. Nonetheless, science has revealed that we are connected in important ways to the cosmos beyond Earth. The atoms that make up Earth and our bodies were formed in stars billions of years ago. The Sun warms our planet and is the reason that our planet is not an inhospitable ball of ice.

Another important way that celestial objects have directly influenced the course of life on Earth is through asteroid impacts, such as the one that contributed to the extinction of the dinosaurs during the Cretaceous-Tertiary mass extinction event around 65 million years ago.

Furthermore, the solstices and equinoxes are not just important for cultural reasons. They mark real seasonal transitions, due to the Earth’s axial tilt as it orbits the Sun. In this way, the sacralizing of the solstices and equinoxes is not just superstition. It is an ancient premonition that what happens in the celestial realm really does matter for life on this planet. The ancestral Pueblo of Chaco Canyon appear to have been onto something. It might be a good idea for the modern world to listen.

Top image: The Fajada Butte Sun Dagger in Chaco Canyon in New Mexico is a spiral petroglyph that is lit up with brilliant streaks of focused Sunlight at key moments in the year. Source: YouTube screenshot / Mystery History

By Caleb Strom


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As a lifelong resident of the 4corners area, I have visited many, many of these ruins. I am constantly amazed more about what is left here, than what achedemics think about it. Since the relatively new science of archeoastronomy, it's just about possible to find a 'sun dagger' type of seasonal sun dial in nearly every ruin of any significance. This should be no surprise. Agriculture ment life, and it's failure ment starvation. Irrigation and staple crops of the three sisters, corn, beans, and squash were paramount to survival. There are much greater mysteries here that are not understood. I have little faith that these will get attention. Too much investment in a narrow narrative by achedemia and current indigenous stakeholders. Sad. Intriguing none the less.

Caleb Strom's picture


Caleb Strom is currently a graduate student studying planetary science. He considers himself a writer, scientist, and all-around story teller. His interests include planetary geology, astrobiology, paleontology, archaeology, history, space archaeology, and SETI.

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