Construction of Stonehenge may be related to rare lunar event, study says

For those who have gathered over the centuries in Stonehenge — the imposing prehistoric monument that dominated Salisbury Plain in southwest England some 4,500 years ago — it was probably clear how the Sun may have interfered with its design.

The central axis of the stone circle was, and still is, aligned with sunrise on the summer solstice and sunset on the winter solstice, the stones framing the sunrise and sunset when they were at their earliest. long and shorter. But does Stonehenge — and potentially other megalithic monuments around the world — also align with the Moon?

The idea that Stonehenge was somehow linked to the Moon gained traction in the 1960s. However, the concept had not been explored systematically, according to Clive Ruggles, professor emeritus of Archaeoastronomy at the School of Archeology and Ancient History at the University of Leicester, in England. This summer, archaeologists are using a little-known lunar phenomenon that happens every 18.6 years to investigate why Stonehenge was built.

Lunar stagnation

Like the Sun, the Moon rises in the east and sets in the west. However, the rising and setting of the Moon moves from north to south and vice versa within the space of a month. The northern and southern extremes also change over a period of about 18 and a half years. Lunar doldrums occur when the northernmost and southernmost Moonrises and sunsets are further apart.

“Moonrise changes every day and if you follow this for a month, you will notice that there is a northern limit and a southern limit beyond which the Moon never rises (or sets),” said Fabio Silva, senior professor of Modeling Archaeology at Bournemouth University, by email. And he added: “If you observed these limits over 19 years, you would notice that they change like an accordion: they expand to a maximum limit (the great lunar stagnation) and then begin to contract to a minimum limit (the small lunar stagnation ).”

This great lunar standstill is predicted to occur in January 2025. However, until mid-2025, the Moon may appear — to a casual observer — to be unusually low or high in the night sky during the lunar month.

“If you are in one of these 19 years, from time to time you will see the Moon rising or setting much further north or south than most of the time. In the intervening years, you never see her there,” Ruggles said.

Despite the phenomenon’s name, the Moon is not actually stationary during this period, he commented. “What is stopped are these limits and the moment when this happens is in January of next year [2025],” Ruggles added. “But for about a year on either side, if you catch the moonrise at the right time, you will see it rising exceptionally low. [no céu].”

Stonehenge is made of two types of stone: larger sarsen stones and smaller blue stones that form two concentric circles. Ruggles said Stonehenge’s stationary stones — which form a rectangle around the circle — roughly align with the edges of the Moon during lunar doldrums. How this lunar alignment was achieved, whether it was by design, and what its potential purpose is is the topic of debate the team wants to investigate.

Investigating Stonehenge’s celestial connections

Although there are no written documents that elucidate the meaning and importance of Stonehenge, archaeologists have long believed that its solar alignments are intentional. Such conformities have been identified in many places around the world and would have been relatively easy for ancient builders to identify, given that knowledge of the Sun’s annual cycle and its connection to the seasons would have been essential for subsistence.

However, it is much more difficult to say whether Stonehenge actually has a connection to the lunar doldrums. “I don’t think we can say definitively, but to me, there is some evidence that makes me think it was deliberate,” Ruggles said.

One clue was the fact that archaeologists found cremated human remains clustered in the southeast, close to where the moon’s southernmost rise will occur. “I think there’s a possibility that they were aware of that direction of the Moon and that it became some kind of sacred direction,” 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 the rising and setting of the Moon at crucial moments when the Moon is aligned with the stationary stones. The Moon is expected to align with the rectangle of stationary rocks twice a month between February 2024 and November 2025, Silva said.

“This will happen at different times of the day and night throughout the year, with the moon being in the right place at different phases each month,” Silva said in an April press release. The team wants to understand what patterns of light and shadow the Moon creates at Stonehenge and whether they may have had meaning for the people who built and used the monument.

Other monuments with a possible lunar connection

Stonehenge is not the only megalithic monument potentially linked to lunar stagnation. In the United States, Erica Ellingson, professor emeritus of Astrophysics at the University of Colorado at Boulder, is investigating lunar alignments at Chimney Rock, a rocky ridge about 300 meters above the floor of a valley in Colorado, United States. The landmark features two large pillar-shaped rocks that frame the horizon.

Between the 900s and 1150s, the ancestors of the Pueblo people built multistory buildings and ritual spaces at this hard-to-reach site with its dramatic views, Ellington said. Still, it is an important location for the 26 Native American groups that have traditional or cultural ties to the area.

“The extraordinary view of the sky between the twin peaks suggests an astronomical connection, but the gap is slightly too far north for the Sun to ever shine through it. The Moon, however, can be seen rising there when it is near its most extreme northern position, during the season of great lunar stagnation,” she said in an email.

Additional Moon-sighting evidence comes from tree-ring dating of wooden beams in nearby ancient buildings, which indicates their construction is linked to the dates of lunar stagnations nearly a thousand years ago, she added. The Calanais Footstones, located on the Isle of Lewis in Scotland and erected before Stonehenge, may also have a link to lunar stagnation, Ruggles said.

Bradley Schaefer, professor emeritus in the department of Physics and Astronomy at Louisiana State University in the United States, said he was deeply skeptical that the ancients were aware of the lunar doldrums and built monuments in line with it. He suggested that this was most likely a coincidence.

“Every ancient site has dozens to hundreds of potential sightlines, and one or more will always point somewhere near one of the eight stagnation directions,” he said in an email. Lunar stagnation is difficult for a casual observer to recognize, he added, and is only really visible in detailed data on moonrise and moonset analyses.

Although the change in the satellite’s position is subtle and historical records documenting the lunar doldrums are rare and difficult to interpret, Ellington said he thinks the link is plausible because many ancient people watched the sky very closely. “An observer of the Moon would have seen it begin to rise or set outside these limits, moving further and further outside the limits as the great lunar doldrums approached,” she said.

This content was originally created in English.

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