Stonehenge Astronomy III: Lunar Alignments

Phases of the Moon. Photo by Fort Photo.

The Moon poses many more problems than the Sun at Stonehenge. Like the Sun it moves between northern and southern limits, taking just under a month to complete the trip. However it also has phases and these can occur anywhere in the cycle. There are however some patterns. In midsummer the Full Moon will occur when it lies in the southern sky. In midwinter the Full Moon occurs when it’s at its northernmost. So you should be able to plan for a Full Moon to some extent if you want a certain Lunar je ne sais quoi for your ritual. However it’s not that easy. Yes the Moon moves between limits, but these limits aren’t fixed. They move too.

[FLASH]http://archaeoastronomy.co.uk/wp-content/images/stonelunar.swf, 500, 375 [/FLASH]The variation of the Lunar limits

The variation is due to a wobble in the Moon’s orbit around the Earth and takes 18.6 years to cycle. This means that the southernmost Full Moon this year could be a lot higher in the sky in a few years time.

At Stonehenge the most obvious (?) lunar alignment is in the station stone rectangle. The short sides face the rising midsummer sun or midwinter sunset. The long sides face the most southerly rising of the Moon. Is this deliberate? It might be. However at this latitude, with a flat horizon, it’s impossible to set up a rectangle with sides that face the Sun axis without also having the other sides face the Moon anyway.

[FLASH]http://archaeoastronomy.co.uk/wp-content/images/stonestation.swf, 500, 375 [/FLASH]The alignments in the station stones: Yellow is solar, White is Lunar.

There is another possible Lunar event that will work if the weather holds.

At the Scottish Recumbent Circles they have a long megalith on their side framed by two tall upright megaliths. At its extreme the midsummer Full Moon gets so low that from the centre of the circles it appears that the Moon is rolling along the recumbent megalith. It’s as if once a generation the Moon comes down and rolls along the Earth. This doesn’t happen at Stonehenge. It’s too far south. However if you lifted the recumbent stones then they would lift the horizon high enough to have the same visual effect. Did the sarsen circle form an artificial horizon?

Easter Aquhorthies Stone Circle. Photo by Snowclaws.

I’ve calculated that on the evening of June 20, an almost Full Moon will be seen rolling along the top of the trilithons from somewhere in the Channel 5 model. I can’t exactly plot where, but I suspect from my back-of-the-envelope calculations that it’s be around the centre of the circle.

Significant?

Probably not. The moon will be fuller and lower the next night, but that’s after transmission. The next year is the Lunar maximum so the moon will reach an even lower point. However that might not be an issue if the effect was meant to be symbolic rather than scientifically accurate. —–