How a lunar ‘standstill’ is shining new light on Stonehenge

It may seem fanciful, but as darkness approached – and with it a vanishingly rare lunar event – it felt as if the beasts and the birds of Stonehenge sensed something strange was afoot.

The song of the skylarks and the flight of the starlings seemed particularly energetic; hares, animals that have mythical associations with the moon, loped with apparent purpose around the stone circle; the humans who had gathered at the monument became skittish.

Stonehenge is, of course, closely linked with the rising and setting of the sun but there is also a growing body of thought that the ancient people who built the circle were also fascinated by the moon – and conscious of a phenomenon now taking place called a “major lunar standstill”, something that only happens every 18.6 years.

This weekend, archaeologists, astronomers and archaeoastronomers (who study how prehistoric people responded to the sky) arrived at the time of the full moon to explore the theory that the Stonehenge creators may have set up some stones to mark the lunar standstill, when moonrise and moonset are farthest apart along the horizon.

“It’s very exciting,” said Clive Ruggles, an emeritus professor of archaeoastronomy at the University of Leicester. “This is a special night because the moon is passing at its lowest possible path through the sky and also it’s full while it’s doing it so it’s the two things together.”

Ruggles, who was armed with charts, cameras and a theodolite, said the key was four “station stones” that form the corners of a rectangle framing the stone circle. When the moon rises at its most southerly point and sets at its most northerly, it aligns with the station stones.

“Was this all intentional?” asked Ruggles. “My own idea is that yes, I think people were aware that every 18th or 19th year, there were times when you could see the moon rising exceptionally far south, and setting exceptionally far north, and people knew about it and remembered it.”

Heather Sebire, English Heritage’s senior curator for Stonehenge, said it made sense that the builders of Stonehenge would take notice of the moon. “They were the first farmers. They must have been observing the weather, the seasons. So they would have been looking at the moon as well.”

Sebire said some of Stonehenge’s bluestones caught the moonlight beautifully, adding: “That might be one of the reasons they used them.” She also explained that, during the early phase of Stonehenge, people were burying the cremated remains of the dead in part of the monument that aligns with the station stones. “There may be something in all this,” Sebire said.

Jennifer Wexler, a Stonehenge historian for English Heritage, said the expansive nature of the landscape made it a wonderful place to watch not only the falling sun but the rising moon, especially when it is a large one. “It feels like this kind of seesaw of cosmic entities. It’s very powerful.”

Those present had a sense of kinship with other sites across the world where the full moon standstill was being observed. Similar cohorts were watching it at the Calanais standing stones on the Isle of Lewis in Scotland, at Chimney Rock, Colorado, a Chacoan ancient settlement, and at the Griffith Observatory in Los Angeles.

Modern life does trespass on the phenomenon at Stonehenge. Cars and lorries roar past close by on the A303 and, unfortunately, a plantation on the horizon obscures the sight line to the spot on the horizon where the most southerly moon first appears.

Only two of the four station stones are still in place. Markers show where English Heritage believes the two missing stones were positioned – but some of the archaeoastronomers think one may be slightly out. A temporary marker – a handbag – was placed on the spot where they believe it may have been.

The UK weather, inevitably, also has its say. As the time of the moon rise approached on Friday night, clouds rolled in and there was a fine drizzle. There was a dim glow over the plantation but no great, awe-inspiring moon, making any meaningful measurements tricky.

It wasn’t a disaster. The precise date of the lunar standstill is in January 2025 and it can be studied for months either side.

“It’s a shame the clouds came,” said Fabio Silva, a senior lecturer in archaeological modelling at Bournemouth University. “But these things happen. We’ll have other chances. We’ll be back.”