THE FACT that dawn sunlight will beam into the passage grave at Newgrange tomorrow at the very moment that a full moon begins to pass out of a total lunar eclipse is a remarkable and rare coincidence, according to Prof Tom Ray, an astronomer at the Dublin Institute for Advanced Studies.
“It is the first time it has happened in about 450 years so that is a coincidence enough. The Tudors were in power in England at the time,” he said.
It is even more remarkable that light from the sun and the moon will appear together, with the first sunbeams at dawn coming just as the moon emerges from eclipse.
“That will happen at exactly eight minutes to nine. The two happen to coincide to within a minute.”
This kind of connection is unbelievably rare, Prof Ray said. “It would not have occurred since Newgrange was built.”
He would not be drawn on whether the juxtaposition carried some portent, some special omen about the future.
“I don’t do astrology,” he said.
The passage grave at Newgrange was built 5,200 years ago even before the pyramids.
It was aligned so that a chamber deep underground lights up with sunlight just as the dawn sun brakes the horizon on the morning of December 21st.
It was a remarkable achievement for those who built it using horse cart and hand given it required thousands of tonnes of rock and earth.
Each year hundreds of people flock to Newgrange to be there on the solstice morning, with a lucky few chosen by a lottery winning the right to be in the chamber at sunrise.
The chamber only lights up because of the very fine alignment of the access passage to the rising winter solstice sun. The light actually enters via a shoebox-sized gap above the passage entrance.
Total eclipses are not rare but they are not everyday occurrences either.
The next visible from Ireland will not be until 2015, according to the Irish Astronomical Association.
They occur when the earth passes between the sun and the moon, cutting off the light and casting a shadow over the full moon.
The eclipse starts at about 7.40am when the moon will be very near setting, according to Terry Moseley of the association. It will be low on the northwest horizon, making it difficult to see.
Mid-eclipse occurs at 8.17am, and the moon will be disappearing fast as dawn breaks over Ireland.