Equinox at megalithic buildings in Ireland

Equinox, east, west are words we understand in present days. What they represented and how they were represented 5000 years ago we don't know. Some megalithic buildings seem to be aligned to periods around equinox such as Cairn T at Loughcrew, Knowth with its two passages (one easterly and one westerly) in the Boyne valley and many more.
10 years ago I was fascinated by the (now invisible) area in front on the Newgrange passage; the oval setting, the hut and the bank of yellow boulder clay. Knowth has comparable round settings as Newgrange in front of its two passages.


My mind took some 10 years to grind on this and it realizes now that there could be an important link between these round/oval settings (covered with quartz stones) near the passages entrances and more in particular the kerb stones in front of the passages!


Looking at Knowth, the round settings are in front of the passages and they have a standing stone, which shadows align with the vertical lines on resp. kerb stone K11 and K74 around equinox days. The vertical line and the standing stone act as sun dial to announce equinox (if it is precisely equinox, I don't know after all the excavations). This possible alignment is quiet obvious in my opinion and already noted by more people.
Remember thought, these alignments will be difficult to prove, because both the standing stones and the kerb stones have been moved and relocated, so the question is if they are still at the correct location!


At Newgrange this took me some more time! But if you stand in the oval setting (it is now covered up by sand and grass) you can cast a shadow at equinox sun rise days which aligns with the carved vertical line on kerb stone K1. There was no standing stone found during the excavations of the oval setting, but a small phallus like stone laying almost east-west (O' Kelly, figure 9). If one would place a staff or standing stone at that location, its shadow will align with the vertical line of K1.

Or is the triangular stone shown in Vallancey picture the standing stone on the oval setting?

But I have some problems in identifying the stones. If we number Vallancey stones from left to right with A, B, C and D, then I think the following mapping evolves (if you have other ideas, let me know):

The stones are of course seen in a different view when looking at Vallancey drawing. Here is a photo from the possible standpoint of him:

Cairn T

Cairn T had also a round/oval setting with quart stones in front of the passage (according to O'Kelly, page 76). I have not seen a picture where this setting was at Cairn T. Furthermore there is not a kerb stone with a vertical carved line like at Knowth and Newgrange. So any information is welcome here!


Is this a coincidence? In my opinion: This could be a new clue why these vertical lines are present!
So why a pronounced vertical line on K52 of Newgrange? Was there also a setting on the north side of Newgrange (equinox sunset)? Could it be under the not yet unexcavated part on the north side? Perhaps time will learn.

Another way of finding equinox

The horns of the solstice picture (like made by Charles Ross and also referred to by Brennan [1983] page 190), provides an interesting idea for equinox. Calculating this picture; using Latitude 53 degrees, a vertical sundial gnomon of 1 meter and around 2000 CE one gets the below:
Horns of the sun
(horizontal: time of day [hour], vertical: length of shadow [m] in North direction)

This straight form of the line at equinox time is independent of the latitude! This straight line at equinoxes is thus very interesting; would this have been used in former times to determine equinox?
Some modern sundials also provide lines of declinations and thus these horns.

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Major content related changes: July. 29, 2001