Prof muiris o'sullivan
Very close to Christmas we experience the winter solstice -- which gives us the shortest day of the year and the longest night. Deep inside the Arctic Circle (as Santa prepares for Christmas Eve) the day is so short that it may only last minutes before plunging back into darkness. But, since Ireland lies at a latitude of 53° north, our shortest day takes place on December 21 and lasts 7 hours, 29 minutes and 55 seconds. Sunrise will be at exactly 8.38 and sunset at 16.08.
With atomic clocks and modern technology it is easy to measure time today, but the Neolithic people living at Newgrange 5,000 years ago proved their own scientific skills and built a tomb that tells the time precisely on this shortest day.
Over the entrance to the tomb at Newgrange is a roofbox with an aperture (a gap in the stones) built in such a way that the rising sun at midwinter strikes the floor of the chamber more than 20 metres further down a long tunnel. From December 19 to 23, the light appears suddenly like a golden thread before broadening and withdrawing over a period of 17 minutes. On the middle day -- December 21 -- it hits the back of the chamber with an amazing display of winter sunshine.
The tomb at Newgrange predates the Great Pyramid of Giza by 500 years. The mere idea that Neolithic people would have the ability to construct a monument that captures the winter solstice is mind-blowing.
So why did these stone-age people build this 'time tomb'? Well, it may have represented the beginning of a new year, or it may have had a religious significance that shows the sophistication of their culture. Several other passage tombs in Ireland feature solar alignments at midwinter, midsummer or the equinoxes. At Knockroe, Co Kilkenny, there are two tombs within one cairn, one of which appears to be aligned with the rising sun in midwinter and the other to the setting sun on the same day. Although the engineering skill of these Neolithic people was phenomenal, archaeologists and scientists can't say for certain how or why they went to the trouble of constructing these astrological structures.
Certainly, the astrological power of Newgrange was so significant that later peoples, such as the Celts adopted the site as a sacred place. In Celtic mythology, Newgrange was the home of Aongus, the son of Dagda Mor, the greatest of the Celtic gods and the goddess, Boinn, after whom the river Boyne is named.
Today, the tomb still holds a mystique and lucky winners of a lottery draw get the chance to visit Newgrange at sunrise on the days around the winter solstice so that they can get to measure time as it has happened for 5,000 years.
QUCD archaeologist, Professor Muiris O'Sullivan, specialises in prehistoric archaeology and is an expert in the great passage tombs at Newgrange, Knowth and Dowth.