When a searing flash of lightning crackles through the sky, some spectators marvel at its brilliance, while others duck for cover. A select few, however, may interpret the event as an act of God—and, subsequently, feel inspired to construct an elaborate circle of thousand-pound stones.

At least, that’s what a team of archaeologists now suspects is the case with Scotland’s Callanish (or Calanais) standing stones, a vaguely cross-shaped arrangement of enormous rocks cobbled together nearly 5,000 years ago. Towering above the grass-tufted soil of the Isle of Lewis, the stones’ origins and purpose have long puzzled researchers, several of whom have proposed controversial theories over the years.

The latest group to enter the fray, led by C. Richard Bates at the University of St. Andrews, has come forth with some stellar evidence—literally. As Dalya Alberge reports for the Guardian, a recent geophysical survey conducted near one of the Callanish stones has revealed a star-shaped pattern, forged by at least one massive lightning strike several thousand years ago, in the surrounding earth.

Using remote sensing techniques, the researchers mapped the underground landscape swaddling the stones. They were surprised to come across some unusual signatures around a single stone occupying a site called Airigh na Beinne Bige. Buried in the earth were remnants of fragments of the same type of rock that makes up the Callanish stones—called Lewisian gneiss—which, unlike the peat and clays that stud the island’s dirt, are poor conductors of electricity. This, the team contends, suggests that the solo stone was once part of a larger circle.

Beneath the peat was a more ancient layer containing bits of magnetized earth—an indication that lightning had struck near the long-gone circle’s center at least 3,000 years ago. The dirt’s star-like shape could have been the result of a single massive lightning strike, or a series of smaller strikes that hit the same spot. Either way, the event would have been a rarity, says Bates in a statement. And given its timing, he explains, the strike’s link to the stone circle is “unlikely to be coincidental.”

The evidence can only put a ceiling on the strike’s chronology, not a floor, leaving open the possibility that lightning hit the stones or their surroundings after they were dragged into place.

But as study co-author Vincent Gaffney, an archaeologist at Bradford University, tells Alberge, other stone circles across the United Kingdom appear to have roots in unusual phenomena hailing from the cosmos.

“It is not a great leap of the imagination to believe early societies would have been enamored with natural events,” he says, adding that these ancients perhaps viewed nature as a means of better connecting with religious figures or the spiritual world.

Similar theories, however, have prompted some skepticism in the past. As Melissa Hogenboom reported for the BBC in 2016, the Callanish stones’ origins could be multifaceted, paying homage to both nature and the dead. Given the arrangements’ structural similarities to people’s homes, circles like these may have been built as living quarters for spirits, or as symbols of the departed themselves, Gordon Noble, an archaeologist at the University of Aberdeen, told Hogenboom.

Either way, the driver behind the stones’ placement was clearly significant enough to warrant some serious planning and effort: Lifting and arranging boulders that weigh up to 10 tons apiece is no joke. Many thousands of years later, we can’t ask the makers themselves. But as Alison Sheridan, director of the Standing Stones Trust at Callanish, says in the statement, discoveries like these can still “[help] us get inside the minds of the people who built [these] stone circles.”