Rare lunar event could reveal link between Stonehenge and the Moon | CNN

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To those who have gathered over the centuries at Stonehenge, the imposing prehistoric monument that dominated Salisbury Plain in south-west England for around 4,500 years – it was probably clear how the sun could have influenced its design.

The central axis of the stone circle was, and still is, aligned with the midsummer sunrise and midwinter sunset, with the stones dramatically framing the rising and setting sun when the days were the longest and the shortest.

But do 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 has not been systematically explored, said Clive Ruggles, professor emeritus of archaeoastronomy at the School of Archeology and Ancient History, University of Leicester.

This summer, archaeologists are using a little-known lunar phenomenon that occurs every 18.6 years to investigate as part of their work to understand why Stonehenge was built.

Lunar shutdown

Like the sun, the moon rises in the east and sets in the west. However, the rising and setting of the moon move from north to south and vice versa within a month. The extreme north and south also change over a period of about 18 and a half years. Lunar shutdown occurs when the northernmost and southernmost moonrises and moonset are furthest apart.

“The rising of the moon changes every day and if you follow this for a month you will notice that there is a north and south boundary beyond which the moon never rises (nor sets),” a said Fabio Silva, lecturer in archaeological modeling at Bournemouth. University by email.

“If you looked at these limits over 19 years, you would notice that they change like an accordion: they expand to a maximum limit (the major lunar shutdown), then start to contract to a minimum limit ( the minor lunar stoppage).

This major lunar shutdown is expected to occur in January 2025, but by mid-2025 the moon may appear, to a casual observer, to be unusually low and high in the night sky during the lunar month.

“If you live 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. In the middle years, you never see him there,” Ruggles said.

Despite the phenomenon’s name, the Moon does not stay still during this period, he said.

“What remains still are these limits, and the time that that happens will be January of next year,” Ruggles added. “But for about a year on either side, if you see the moon rise at the right time, you will see the moon rise exceptionally low (in the sky).”

Stonehenge is made of two types of stone: larger sarsen stones and smaller blue stones that form two concentric circles. Ruggles said the Stonehenge station stones, which form a rectangle around the circle, roughly align with the extreme positions of the moon during lunar shutdown.

How this lunar alignment was achieved, whether it was intentional, and its potential purpose are topics of debate the team wants to explore.

Although there are no written records shedding light on the meaning and significance of Stonehenge, archaeologists have long believed that its solar alignments were intentional. Such alignments 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 annual cycle of the sun and its connection to the seasons would have been essential to making a living .

However, it is much more difficult to say whether Stonehenge actually has a connection to the lunar shutdown.

“I don’t think we can say for sure, but to me, there was some evidence that made me think it was deliberate,” Ruggles said.

One clue was the fact that archaeologists found cremated human remains clustered in the southeast, near where the southernmost moonrise will take place.

“I think it’s possible that they were aware of this direction of the moon and that then it became a sort of sacred direction,” Ruggles said.

Since April, Ruggles and Silva, along with colleagues from Bournemouth University, the University of Oxford and English Heritage, the organization that manages the site, have been documenting the rising and setting of the moon at the times keys where the moon is aligned with the stones of the station. The moon was expected to align with the station’s stone rectangle twice a month, between approximately February 2024 and November 2025, Silva said.

“This will occur at different times of the day and night throughout the year, with the moon in the right place at different phases each month,” Silva said in a press release in April.

The team wants to understand what patterns of light and shadow the moon creates at Stonehenge and whether these might have had meaning for the people who built and used the monument.

Stonehenge is not the only megalithic monument potentially linked to the lunar shutdown.

In the United States, Erica Ellingson, professor emerita of astrophysics at the University of Colorado at Boulder, studies lunar alignments at Chimney Rock, a rock ridge about 1,000 feet above a valley floor in Colorado . The monument has two large pillar-shaped rocks that frame the horizon.

Between the 900s and 1150s, the ancestors of the Pueblo people constructed multi-story buildings and ritual spaces on this difficult-to-access highpoint with its spectacular view, Ellington said, and it remains an important site for the 26 Native American groups. who have 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 slightly too far north for the Sun to ever pass through. However, the Moon can be seen rising there when it is near its most extreme position in the north, during the great lunar shutdown season,” she said by email.

Further evidence for moon sighting comes from the dating of rings in the wooden beams of nearby ancient buildings, indicating that their construction is linked to the Moon’s shutdown dates nearly 1,000 years ago. years, she added.

The Calanais standing stones, located on the Isle of Lewis in Scotland and erected before Stonehenge, may also have a connection to the lunar standstill, Ruggles said.

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 aligned with it. this one. It is more likely, he suggested, that it was a coincidence.

“Every ancient site has dozens, if not hundreds, of potential sightlines, and one or more will always point somewhere near one of the 8 stopping directions,” he said by email.

The Moon’s shutdown is difficult to recognize for a casual Moon observer, he added, and is only really visible in detailed data on Moonrise and Moonset observations.

Although the change in the Moon’s position is subtle and historical records documenting the Moon’s shutdown are rare and difficult to interpret, Ellington said she thinks the connection is plausible because many ancient people observed the sky closely.

“A moon observer would have seen the moon begin to rise or set outside of these limits, moving further and further out of bounds as the major lunar shutdown approached,” she said .