Every 18.6 years the Old Woman of the Moors, or Cailleach na Mointeach, an undulating hill formation that resembles a pregnant woman resting on her back, wakes from her sleep to give birth to a rising Moon.

After the Moon rises from between her legs, it sets between the Callanish Stones - widely regarded as Scotland's Stonehenge - and drums are beaten wildly to celebrate the mysterious powers associated with the lunar cycle.

But the spectacle, which attracts pagan worshippers, New Age revellers and archaeologists from across the world to the Isle of Lewis, is now under threat, it is claimed, by plans for a windfarm.

Beinn Mhor Power has applied to build a 53-turbine windfarm on the Eisgein Estate on Lewis - and some of them will be located on the Old Woman of the Moors. One of the turbines is proposed for a lump that passes for her knee, others will break the skyline.

The problem for protesters is that the Callanish Stones, as a national monument managed by Historic Scotland, are protected from development, while the Old Woman of the Moors is not.

Ian McHardy, an archaeologist, said that the lunar phenomenon, which next takes place in 2024, and Callanish were inextricably linked and demanded that the site be given better protection. “I think it's an integral part of Callanish and should have been afforded higher protection,” he said. “The wind turbines would be a significant part of the view.”

Alice Starmore, a local tour guide, said: “It is one of our most intriguing and national treasures. We might as well say that we would build turbines on Stonehenge.”

If the proposal for the windfarm gains approval, it will be the first to be built on a designated National Scenic Area.

While the title carries no statutory protection, it is awarded to Scotland's most outstanding regions of natural beauty.

Helen McDade, head of policy for the John Muir Trust, the UK's biggest conservation charity, said that permitting the windfarm in such an area would set a dangerous precedent. “It is ludicrous that the government would even entertain the idea of marching turbines across such a world-class landscape,” she said.

“Scotland can easily meet its 50 per cent renewable target by 2020 without encroaching on designated areas of national importance such as this one.This proposal would degrade both our cultural and our natural heritage and should be rejected in line with stated government policy.

“Callanish is Scotland's equivalent of Stonehenge and must be left unscathed by industrial development so that it can be fully appreciated by future generations,” she added.

Druids and witches are among the hundreds of New Age revellers who gather at the Callanish Stones. They believe that the stones are sacred and, like Stonehenge, that they were used for important rituals.

Callanish itself is a circle of 13 standing Lewisian Gneiss stones, which are thought by archaeologists to have been erected between 3000BC and 1800BC, with further stone rows added up until the Dark Ages.

Last year more than 20,000 visitors travelled to Callanish, while the number of visitors to heritage sites in Scotland increased by 62,000, or

3.2 per cent.

The controversial plans to build a windfarm close to the ancient site come after ministers last month turned down proposals to build Europe's biggest wind farm - a 181-turbine development - in the north of Lewis.