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For those gathered for centuries at Stonehenge, the majestic prehistoric monument that dominated the Salisbury plains of south-west England for nearly 4,500 years, it was probably obvious how the sun may have influenced the design of this structure.
The central axis of the stone circle was, and still is, aligned with midsummer sunrise and midwinter sunset; The stones dramatically frame the rising and setting sun when the days are longest and shortest.
So is Stonehenge and potentially other megalithic monuments around the world also aligned with the Moon?
The idea that Stonehenge was somehow connected to the Moon gained strength in the 1960s. But Clive Ruggles, retired professor of archaeoastronomy at the University of Leicester’s School of Archeology and Ancient History, said the concept had not been systematically explored.
This summer, archaeologists are investigating a little-known lunar event that occurs every 18.6 years as part of their work to understand why Stonehenge was built.
cessation of the moon
Like the sun, the moon rises in the east and sets in the west. However, the moonrise and sunset move from north to south and back again within a month. The northern and southern extremes also change over a period of approximately 18.5 years. The lunar standstill is the time when the northernmost and southernmost moonrise and sunset are furthest apart.
“The moonrise changes every day, and if you follow it over the course of a month you’ll notice that there is a northern and southern boundary where the moon never rises (or sets),” said Fabio Silva, senior lecturer in archaeological modeling at Bournemouth. University via email.
“If you look at these limits over 19 years, you notice that they change like an accordion: They expand to the maximum limit (major moon pose) and then they start to narrow to the minimum limit (little moon pose). .”
This major pause in the moon is expected to occur in January 2025, but from now until mid-2025, to the casual observer the moon may appear unusually low and high in the night sky throughout the month.
“If you are in one of these 19 years, you will occasionally see the moon rise or set much further north or south than most of the time. You never see him there in the intervening years,” Ruggles said.
He said that despite the name of the phenomenon, the Moon was not actually standing still during this period.
“What’s still standing are those borders, and the moment that’s going to happen is January of next year,” Ruggles added. “But for about a year on either side, if you catch the moonrise at the right time, you will see the moon rising extremely low (in the sky).”
Stonehenge is made of two types of stones: larger sarsen stones and smaller blue stones that form two concentric circles. Ruggles said Stonehenge’s station stones, which form a rectangle around the circle, were roughly aligned with the extreme positions of the moon during the lunar standstill.
How this lunar alignment is achieved, whether it is by design, and its potential purpose are topics of discussion that the team wants to investigate.
Investigating Stonehenge’s celestial connections
Although there are no written documents that shed light on the meaning and significance of Stonehenge, archaeologists have long believed that its alignment with the sun was intentional. Such alignments have been identified in many parts of the world, and would have been relatively easy for ancient builders to detect, given that knowledge of the sun’s annual cycle and its connection with the seasons was essential for subsistence.
But it is much more difficult to say whether Stonehenge actually has a connection to the Moon standing still.
“I don’t think we can say for sure, but it seems to me there is some evidence that suggests this was intentional,” Ruggles said.
One clue was that archaeologists found cremated human remains collected in the southeast, near the southernmost location of the moonrise.
“I think there’s a possibility that they were aware of this aspect of the Moon and that it had become some sort of sacred aspect,” Ruggles said.
Since April, Ruggles and Silva, along with colleagues from Bournemouth University, Oxford University and English Heritage, the organization that manages the site, have been documenting moonrise and sunset at key moments when the moon is aligned with the station stones. The moon is expected to align with the station stone rectangle twice a month from February 2024 to November 2025, Silva said.
“This will occur at different times of day and night throughout the year, with the moon being in the right place at different phases each month,” Silva said in an April news release.
The team wants to understand what patterns of light and shadow the moon cast at Stonehenge and whether these had meaning for the people who built and used the monument.
Other monuments with possible lunar connection
Stonehenge is not the only megalithic monument potentially linked to the moon standing still.
In the United States, Erica Ellingson, professor emeritus of astrophysics at the University of Colorado Boulder, studies lunar alignments at Chimney Rock, a rocky ridge about 1,000 feet above a valley floor in Colorado. The landmark has two large pillar-like rocks framing the horizon.
Between 900 and 1150, ancestors of the Pueblo people built multi-story buildings and ritual sites on this inaccessible high ground with its dramatic landscape, and it remains an important site for 26 Native American groups, Ellington said. Having traditional or cultural ties to the region.
“The extraordinary view of the sky between the twin peaks suggests an astronomical connection, but the gap is too far north for the Sun to shine through it. But the Moon can be seen rising there during the great lunar standstill season, when it approaches its extreme northern location,” he said via email.
He added that further evidence of lunar sightings came from tree-ring dating of wooden beams in nearby ancient buildings, which showed that their construction was linked to lunar standstill dates around 1,000 years ago.
Ruggles said the Calanais Standing Stones, located on the Isle of Lewis in Scotland and erected before Stonehenge, may also have a connection to the moon standing still.
Bradley Schaefer, professor emeritus in the Department of Physics and Astronomy at Louisiana State University, said he is deeply skeptical that ancient people were aware of the lunar standstill and built monuments to accommodate it. He suggested it was probably a coincidence.
“There are dozens to hundreds of potential sight lines at each ancient site, and one or more of them will always point somewhere near one of the 8 stall directions,” he said via email.
He added that the Moon’s standing point is difficult to spot for the casual lunar observer and is only truly visible in detailed data on observations of the moonrise and sunset.
Although the change in the Moon’s position was subtle and historical records documenting the Moon standing still are rare and difficult to interpret, Ellington said he thinks the connection is plausible because many ancient people watched the skies very closely.
“A lunar observer could see the moon starting to move out of those boundaries or starting to set, moving further and further out of boundaries as the great lunar standoff approached,” he said.
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