The Major Lunar Standstill, 2025, and preparations for it in 2024

The complex stone monument at Calanais is world-famous for marking an extraordinary natural phenomenon that happens every 18.6 years, at the time of the moon’s Major Standstill, when its rising and setting positions are at their southernmost point and furthest apart.

At this time, when viewed from the northern end of the Avenue at Calanais, the full moon’s path from rising to setting means that it appears to skim across the horizon (which is shaped like a woman lying on her back – the ‘Cailleach Na Mointeach’, or ‘Old Woman of the Moors’), then disappear from view briefly before shining into the centre of the circle at the southern end of the Calanais monument as it sets.

It is believed that the design of the monument at Calanais was deliberately changed, probably around 2500 BC, to re-orientate the monument so that it was aligned on this remarkable lunar event. Before that, it had existed as a free-standing stone circle with a tall central stone, built around 2900 BC, whose orientation is believed to have been concerned principally with marking winter solstice (i.e. an event connected with the sun, not the moon). There is evidence for a small chamber tomb being constructed inside the stone circle around 2500 BC, and it may well be that that the northern Avenue and perhaps also the East, West and South rows were added around this time. It was the construction of the Avenue that directed people’s gaze and movement towards the position of the Major Lunar Standstill.

The last time the moon’s Major Standstill was marked was 2006, and it is due to happen again in 2025 – but the Major Standstill season starts this year, when it will be close enough to its 2025 position for the phenomenon to be witnessed. Urras nan Tursachan are hoping to work with our friends in English Heritage, who are live-streaming the event at Stonehenge this June, and we hope to offer a live-stream from Calanais on the night of 22 June, 01:16 (moonrise) till 03:19 (moonset), British Summer Time – if this proves possible from a technical and logistical point of view. We shall also be recording the phenomenon at various times when it is visible, and this footage will feature on our website and in the new Visitor Centre when it opens in a couple of years’ time. Of course, there is no guarantee that the sky will be free of clouds, but watch this space! Note that this will occur shortly after the summer solstice on 20th (sunset)/21st (sunrise) June.

Other dates to watch (all British Summer Time) are:

19–20 July 2024, between 22:55 (19th) and 0.04 (20th)

15 August 2024, between 21:57 and 23:48

11 September 2024, between 19:42 and 21:34

..and in 2025:

12th June, between 01:57 and 03:54

9–10 July, between 23:48 (9th) – 01:47 (10th)

5–6 August, between 22:36 (5th) and 00:31 (6th)

1 September, between 20:30 and 22:19

Note that Urras nan Tursachan cannot guarantee that the phenomenon will be visible on any of these dates, nor can it guarantee the accuracy of the information presented here. Any visits made to Calanais to try and see the phenomenon are the responsibility of the visitor, not of Urras nan Tursachan.

Note also: The monument at Calanais was constructed as a sacred site, not as a destination for mass tourism, and it is vulnerable to damage from excessive footfall from visitors. It will not be possible for large numbers of people to witness the phenomenon at the monument itself and there is only very limited parking space, so in-person visits to the site at these times are not encouraged.

If you want to find out more about lunar standstills, see:

View of The Major Lunar Standstill Season is Here! (equinoxpub.com)

And if you want to find out about the Standstill at Stonehenge, see:

Stonehenge Major Lunar Standstill | English Heritage (english-heritage.org.uk)