Few ancient monuments are shrouded in as much mystery as Stonehenge, the strange prehistoric temple in southern England, whose construction began almost 5,000 years ago. Its builders and designers left no written word to explain its meaning, nor do we know what it was used for all those years ago.
Modern analysis tells us that the ancient Britons transported these megaliths – many of which weigh more than 20 tonnes – from quarries somewhere far from the site of Stonehenge.
We also know that the structure is aligned with the Sun at the summer and winter solstices. But the importance of this to the people themselves is largely lost.
The only thing the experts were Really The question, at least until now, was whether Stonehenge was built not only to be aligned with the Sun – an impressive feat for a society that had not yet invented the wheel – but also with the Moon.
On June 21, 2024, a team of experts hopes to answer exactly that question, as a major, once-in-a-generation lunar shutdown begins.
Its meaning? Professor Michael Parker Pearson, an expert in later British prehistory at University College London, tells BBC Science Focus that if Stonehenge were aligned with this event, it would show that its builders “linked the movements of the Sun and the Moon into a kind of grand unified theory of the Neolithic.”
“With all the Stonehenge stones transported from far and wide (which is unique among the 900 stone circles in Britain and Ireland) and with so many people buried at Stonehenge, this would have been a monumental attempt to unify people , ancestors, earth and cosmos.”
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What is a major lunar shutdown?
During a major lunar shutdown, which only occurs every 18.6 years, the Moon reaches its most extreme northern and southern positions in the night sky. Imagine that the Moon rises and sets much further north and south than usual, forming a wider arc in the night sky.
This may resemble the way the Sun’s path changes throughout the year, reaching its northernmost and southernmost points at the summer and winter solstices. Indeed, the word “solstice” derives from the Latin words “sol” and “stice”, literally meaning “the stopping of the sun”.
However, there is a key difference between the Moon stopping and the Sun stopping. The Earth’s tilt relative to the Sun causes the solstices to occur at more or less the same times each year.
In contrast, the Moon’s orbit also has a tilt, but this tilt changes slightly over time. This is why the most extreme positions north and south of the Moon change on 18.6 year cycles, creating this major and dramatic lunar shutdown effect that will occur over the next year.
During the major lunar shutdown each month, the Moon’s highest point in the sky may be higher than the Sun’s highest point in summer, and its lowest point may be lower than the Sun’s lowest point in winter.
- You can watch the southernmost moonrise of the major lunar stop at Stonehenge on the English Heritage YouTube channel, where it will be streamed on June 21 at 9:30 p.m. BST (4:30 p.m. EDT in New York, 1:30 p.m. PDT in Los Angeles).
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What does Stonehenge have to do with it?
Stonehenge’s alignment with the summer and winter solstices is well known, with crowds gathering each year to mark the events at the site. But its link with lunar cycles, which are more difficult to follow, is less well understood by experts.
Research estimates that between 3,000 and 2,500 BCE, before the large stones were brought to the site, burials and cremations took place there.
Many of them were clustered toward the Moon’s southernmost ascending position during major stops, and three wooden posts were installed in the bank at this location.
Later, four so-called “Station Stones” were brought to the site, forming a rectangle in its center.
“The four Station Stones align with the extreme positions of the Moon, and researchers have debated for years whether this was deliberate and, if so, how it was achieved and what their goal might have been,” explains Professor Clive Ruggles, Emeritus Professor of Archaeoastronomy. at the University of Leicester.
The Station Stones themselves were likely used to measure the iconic ‘Sarsen Circle’ which was added around 500 years after the first burials at the site, according to English Heritage.
So, if they are linked to the Moon stopping, this would suggest a more fundamental role for the Moon in the architecture of Stonehenge as a whole than previously thought.
To find out whether the lunar standstill was at the heart of Stonehenge’s design, academics from the universities of Oxford, Leicester and Bournemouth plan to study the event between now and its end in 2025.
“Unlike the Sun, tracking the Moon’s extremes is not simple and requires specific timing and weather conditions,” says Dr Amanda Chadburn, an archaeologist from the University of Oxford.
“We want to understand a little about what it was like to experience these extreme moonrises and moonsets and to witness their visual effects on the stones (e.g., patterns of light and shadow), to consider the modern influences like traffic and trees, and to document it all through photography for future studies.
About our experts
Mike Parker Pearson is Professor of Later British Prehistory at the Institute of Archeology, University College London (UCL). After completing a BA in European Archeology at the University of Southampton in 1979, he completed a PhD at the University of Cambridge in 1985. He worked as an inspector of ancient monuments for English Heritage until 1990. From then on , he taught in the Department of Archeology and Prehistory at the University of Sheffield where he obtained a professorship in 2005, which he held until his arrival at UCL in 2012. He is a member of the British Academy.
Clive Ruggles is Emeritus Professor of Archaeoastronomy at the University of Leicester. From 2008 to 2018, Ruggles coordinated the IAU Astronomy and World Heritage Initiative jointly with UNESCO and continues to advise governments on potential astronomy-related World Heritage nominations. In 2017 he was awarded the Agnes Mary Clerke Medal of the Royal Astronomical Society for “a lifetime of distinguished work in the overlapping fields of archaeology, astronomy and the history of science”.
Amanda Chadburn is a professional archaeologist and historic environment consultant. She began her professional career in local government and joined English Heritage in 1987 where she held various administrative and policy positions. She has taught archeology and heritage management at the Universities of Bristol, UCL and Oxford, and has co-supervised doctoral students at the Universities of Bristol and Huddersfield.
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