Twenty years ago, in the summer of 1999, Michael Byrne placed his binoculars along the edge of the larger of two standing stones at Baltray, Co. Louth, and found that he could see the islands of Rockabill in his field of view. That was to lead to the discovery of the winter solstice alignment of the large stone towards Rockabill. Michael, Richard Moore and Anthony Murphy returned to the stones for a 20th anniversary celebration.
Recently, while writing my new book about the discovery in summer 2018 of a giant henge near Newgrange, dubbed 'Dronehenge",I wrote an introductory chapter about how the whole journey of exploration into myths, megaliths and astronomy began. And really it started with Baltray, 20 years ago.
In early July 1999, Michael Byrne, an amateur astronomer and photographer from Drogheda, on a visit to the pair of standing stones with Richard, placed his binoculars against the edge of the larger of the two stones and could clearly see the Rockabill islands, which are located off the east coast of Co. Dublin in the Irish Sea, in his view.
When Richard Moore first took me to the standing stones a short time after that, I, like Michael, wondered how he knew their location. They are situated such that they are not visible from a nearby laneway, tucked away at the far end of a field of pasture where they overlook Baltray Golf Club and the Irish Sea. Richard is a rambler, someone who likes to travel by less trodden paths, and who finds all sorts of things as a result.
He told me about Michael's observation. I was interested in the apparent alignment because if the large stone was pointing to Rockabill, it could be that Rockabill was used as a distant foresight for an astronomical alignment. Richard had his old ship's compass with him and we took a magnetic azimuth measurement. That azimuth was approximately 130°.
That azimuth is not far from southeast (135°) and would correspond with the place where the sun would rise at winter solstice, on the shortest days of the year.
"That's winter solstice sunrise," I said. Richard was sceptical. The problem was that it was July. Winter solstice was five months away. We could not prove or disprove my suggestion until then.
In the meantime, I used free astronomy computer software to calculate the approximate azimuth of winter solstice sunrise from this location. The result was indicating an azimuth of approximately 130°.
Months later, with winter solstice approaching, we decided that I would go to Newgrange to photograph winter solstice sunrise there, while Richard and Michael would go to Baltray to witness sunrise there. They arrived at the standing stones just as the sun was rising, and just in time to witness it emerging out of the Irish Sea at a short distance – about two sun-widths – to the left of Rockabill. Michael made a recording of the sunrise on his video camcorder.
After the solstice celebrations had finished at Newgrange, I made my way home and phoned Richard. He told me about the sunrise, and that it was a little bit to the left of Rockabill. I was not disappointed. This was almost certainly an indication of an intended alignment some time in prehistory, possibly in the Neolithic.
Why the difference in the sun’s position, Richard wondered. The earth’s equatorial plane is inclined at an angle to the plane of its orbit. This is termed the “obliquity of the Ecliptic” and this is what causes the seasons on earth. There is a slight wobble of the earth’s axis called nutation which causes the obliquity of the Ecliptic to slowly oscillate over a long period. The result of this is that the obliquity varies between 22°0’ and 24°30’ over a period of 40,400 years. Right now, the obliquity of the Ecliptic is approximately 23.4°, but 5,000 years ago it was approximately 24°. This would cause the sun’s rising position at solstice to change as a result. So any initial disappointment about the sun coming up to the left of Rockabill viewed from the large stone at Baltray was dispelled. The next day, I viewed the video footage in Michael Byrne’s house and was tremendously excited. We had made our first discovery. The first of many.
Spurred on by our discovery, Richard and I continued researching astronomical alignments of prehistoric sites, becoming the first people in modern times to witness the summer solstice sunrise alignment of the great Dowth henge (Site Q) the following year. We published our book Island of the Setting Sun - In Search of Ireland's Ancient Astronomers in 2006. My own research and writing has continued ever since. I have now published five books in total, with a sixth written and the seventh – my book about the discovery of Dronehenge – in progress.
It all began at Baltray really, with our discovery in 1999, and Richard Moore's tenacity, and Michael Byrne's keen observation skills. It's hard to believe it's been 20 years since that discovery. Time flies. It really does.
One thing that struck me recently, while writing my new book about Dronehenge, was that we had never had a photo taken together as a trio at the time of our discovery. We have lots of photos from the standing stones, but none with the three of us together. So I thought about putting that right, and how nice it would be to have the three of us come together at Baltray 20 years later.
I'm very glad for the friendship of these two men, and for our discovery as a trio at Baltray in 1999. It was the beginning of a long, exciting and fruitful journey of exploration for me, one which reached an apex in July 2018 with my discovery of Dronehenge (with Ken Williams, another great Drogheda man!).
It is a wonderful tribute to our discovery that the local people from Baltray and surrounding area come together every winter solstice at the standing stones to witness the sunrise.
Thank you gentlemen, for your wonderful spirit of investigation and curiosity, and for companionship, and most of all, for helping me set out on a great journey.