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Established 16/3/2000

Equinox sunlight in Knowth west

Brief observations made by Mythical Ireland at Knowth's western passage on the Autumn Equinox, September 22nd, 2000, confirm that the sunlight does penetrate the passage at equinox. The event has rarely been seen, partly because of the bad weather which prevails at this time of the year in Ireland, but also because of extensive archaeological and reconstruction work which has been ongoing at Knowth for over 30 years. These photographs clearly show the sunlight on the passage orthostats, and I present them to you here in another internet exlusive.

Sunlight in Knowth's western passage on the Equinox

The event lasted only a few minutes before the sun sank below a large bank of clouds in the west. But it was a glorious moment as the sun's rays illuminated the southern wall of orthostats about one-third the length of the passage.

From outside the sunlight on the wall of orthostats was clearly visible. At this time, 6:46pm BST on September 22nd, the shadow of the standing stone, or gnomon, outside the western passage entrance, was almost exactly in line with the carved vertical line on the entrance kerbstone. The photograph below shows the sunlight on the southern wall of orthostats.

Sunlight on the orthostats
A view from outside the entrance showing the sunlight on the stones inside.

Gnomon standing stone
Sun in the passage
A view of Knowth's western entrance during excavation showing the gnomon standing stone. Sunlight in the western passage at Knowth. Just seconds later the sun went behind cloud and the fantastic show was over.

Inside the western passage, I could see that the sunlight extended some distance into the passage, but the sunbeam became very low to the ground the further in I went. After the sun went behind cloud, the light became diffused, and as my eyes adjusted to the dark I could see that the light extended right down into the passage, as far as the bend.

Orthostat 73 - an equinox marker

The sunbeams extended as far as the bottom portion of this stone, which is orthostat number 73, located on the southern wall of orthostats. It is decorated with zig-zagged designs which possibly represent a marker for the penetration depth of the equinox sunlight into Knowth west.

An illustration showing the sun's penetration of the passage

The above illustration shows two lines of sunlight - the yellow one represents the penetration of sunlight on the Autumn Equinox, September 22, as far as orthostat 73. The red line represents the maximum penetration of sunlight into Knowth west, as far back as orthostat 34, which can be seen pictured below. This hypothetical line of penetration is the result of measurements undertaken by the Mythical Ireland team, Anthony Murphy and Richard Moore, along with Victor Reijs of Geniet, in September of 2000. Orthostat 34 contains a number of curved carvings which may represent calibration marks for the sun. The results of the measurements at Knowth west can be seen on the Geniet website.


Orthostat 34
Looking towards the chamber
Orthostat 34, the furthest point of sunlight penetration in Knowth west. The passage bends noticably at this point. A photo from inside Knowth west showing the view towards the central chamber, taken from near orthostat 34.

The line of furthest penetration of sunlight is based not only on measurements made in Knowth west, but also based on eyewitness reports from two people who told Mythical Ireland that the sunlight penetrates as far as this stone about a week or so after Autumn Equinox.

Acknowledgments:
Kind thanks to Professor George Eogan, who not only took me on a personal guided tour of Knowth on July 19th, but then invited me to see the equinox event for myself. Professor Eogan is director of excavations at Knowth for over 30 years.

Other pages of interest:
Inside Knowth west - 5,000-year-old megalithic engravings.
Knowth Lunar calculations - lunar calculations revealed on kerbstone.

Back to the Knowth page

All information and photos, except where otherwise stated, copyright, © Anthony Murphy, 1999-2015
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