BIRKRIGG'S STONE RINGS

1. WHY HERE?

Cumbrian stone rings, in particular, frequently have alignments to the rising sun. Locally, Swinside has a portal to the mid-winter sunrise; Banniside (below Coniston Old Man) has a marker stone to the north-east for the mid-summer sunrise. Uniquely at Sunbrick, every sunrise between mid-winter and mid-summer is visible on a distant horizon; key features on the horizon, not the positions of the stones, mark the progress of the sun. Surprisingly, this aspect of the Birkrigg stone rings seems to have been seriously over-looked in the past. There is possibly no other stone circle in the country which offers this facility to view the full annual cycle of sunrise so clearly on the horizon – it’s like watching a pendulum swing one way over six months, then back again.

At the mid-winter solstice, 21st December, the sun rises around 8.30 a.m., at its most southerly point of the year. When seen from the Sunbrick stone rings this is behind the Bowland Fells, just as Hawthornthwaite Fell dips sharply to the west. For several days the sun appears to be standing still (hence solstice), rising at the same point each day*.

Then the sun begins its apparent journey northwards, the position of the sun's rising moves a little further towards the north each day. At the mid-point, at the spring and autumn equinoxes of equal night and day in March and September, sun rise occurs immediately behind Ingleborough, a very recognisable outline on the horizon (behind Humphrey Head in the foreground); it occurs at 6 a.m. (7 a.m. in autumn due to B.S.T.).

Finally, at the mid-summer solstice, on 21st June, the sun rises at its furthest point north; when seen from the stone rings, this event occurs just beyond the northern end of Chapel Island in the estuary (at least as it was before it was denuded by quarrying in Victorian times).

 

*For the purist, the movement in the position of the sunrise occurs because of the earth’s tilt on its axis. The tilt of the earth’s axis oscillates between 24.5° and 22° on a 41,000 year cycle and is currently decreasing. The extremes of northern and southern rising points of the sun during the year will therefore change slightly over this cycle, but it is less than ½° (about the sun’s width) over the 4000 years that the stone rings may have existed.

Sunbrick also provides the perfect place to observe the moon. Like sun rise, the position of moon rise changes from north-east to south-east and back again, but over a period of 29 days rather than one year.

The pattern for the moon is the reverse of that for the sun. The full moon nearest to the mid-winter solstice rises in the early evening and at its furthest position north for that year, while in mid-summer full moon rises late in the evening, at its furthest position south for the year.

A mid-winter full moon will rise just before the sun sets about 5 p.m.. On 3rd January 2015, at a minor lunar standstill, the moon rose just behind the north end of Hampsfell, as the last of the sun’s rays caught the tops of the stones in the ring. This was at the northenrmost point for the year.

Six months later, on 2nd July 2015, the full moon rose at 9.30 p.m. at its most southern point of the year, behind the Trough of Bowland:-
The full moon nearest to the autumn equinox, rising in the vicinity of Ingleborough, is known as the Harvest moon. In times when harvests were gathered manually this allowed all night working, as there were 12 hours of moonlight (clouds permitting). Additionally, at this time of year the moon rises about 35 minutes later each day, earlier than the average for the year, so it seems that the full moon lasts several days, allowing the harvest to be completed.
On 28th September 2015 the full moon occurred when the moon was at its closest to the earth in its orbit, a perigee or supermoon. In addition, at around 4 a.m., there was an eclipse of the moon creating a blood moon. What our Bronze Age ancestors would have made of this demonstration by the gods is anybody's guess!

So clearly, the choice of site for Birkrigg’s stone rings is related to its elevated position and the open aspect to the east, giving a panorama which embraces the northern and southern extremes of sun rise and moon rise during the year.

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