Spring has sprung. At 16.15.21 GMT today, Tuesday March 20, the Sun passed the celestial equator (the imaginary line in the sky above the equator) and night and day were, on this date, the same length. This is the Vernal or Spring Equinox and it marks the end of Winter or the first day of Spring, depending on how you look at it.
Space.com reckons that if you were standing on the equator at a point just to the west of the Itapará River in northern Brazil, the sun would appear directly overhead. On the Dingle Peninsula the Equinox is marked in a very different way. Dáithí Ó Connaill of Tralee Mountaineering Club discovered that the setting Winter sun shines into a megalithic tomb in Loch A’duin (The Lake of the Fort). Loch A’duin is located just below the Conor Pass on the the Dingle Peninsula. Dáithí is the best person to describe it.
The Vernal or Spring Equinox in in Loch A’duin, on the Dingle Peninsula
The following is a brief account of my curious “discovery” regarding the equinoctial sunsets at the megalithic tomb in Loch a’Duin:
The “discovery” was made following a hunch that the bronze age tomb of approximate date of 2500 B.C., which has a westerly orientation, may have had some significance due to the fact that it is embellished internally with some prehistoric rock art, leading one to surmise that it may have had some ritualistic significance, similar, in a minor way, to the passage tomb of Newgrange in the Boyne Valley, which is oriented on the winter solstice sunrise.
It was visited at the winter solstice annually over fifteen years but, invariably, the sunset was not visible due to either cloud cover or rain. There was a brilliant sunset on the winter solstice of 2014 but, alas, it did not have any unusual bearing on the tomb’s orientation.
However, this led to a little thinking as to the possibility that it may have had some relevance vis-a-vis the vernal and autumnal equinoctial sunsets around March 21st and September 21st. The reasoning behind this curiosity was that, when one looks at the orientation of the monument, it seems to face directly into an imaginary “v” formed by the spur of nearby “Sliabh Mhacha Reidh” and the distant spur of “An Gearan”.
It transpired that the equinoctial sunsets of September 2015 and March 2016 were visible and it was delightfully noticed that the sun on both occasions(and indeed over a few days preceding and subsequent to the equinoxes) bisected the “v” and spectacularly illuminated the tomb and the rock-art therein.
There are many theories abroad as to why our distant ancestors went to such careful planning and should lead to interesting discussions.
Dáithí Ó Connaill
The Mountaineering Collective 