The winter solstice and the “Newgrange effect” at Elizabeth Bay House

Elizabeth Bay House in Sydney illuminated by the Midwinter sunrise, image Nick Lomb

This morning (21 June 2008) the sun was at its furthest north and hence today is Midwinter Day and the shortest day of the year. To celebrate the phenomenon I was invited to a Winter Solstice Breakfast at the Historic Houses Trust’s Elizabeth Bay House. The event was to view a rare and spectacular phenomenon – the central axis of the house flooded with sunlight soon after sunrise. This effect was discovered last year by Gareth Malone, an HHT staff member. Fortunately, after days of rain the Sun managed to climb out of a bank of clouds on the horizon and provide great viewing for all those present at the breakfast.

Looking along the central corridor of Elizabeth Bay House, image Nick Lomb

The sunlight does not reach into the corridor until a few minutes after sunrise as the house is built above sea level and the Sun takes that time to rise a degree or so above the horizon. The light can reach into the corridor on other mornings but then it is higher above the horizon and so would not penetrate through the house to the cliff face beyond as it does at Midwinter. As everything else about the design of the 1835 house shows careful thought by its original builder Colonial Secretary Alexander Macleay and the architect John Verge, the alignment of the house is unlikely to be accidental. There is, however, no known written reference to the subject in the archives.

Looking into the Sun along the main corridor of Elizabeth Bay House, image Nick Lomb

The whole effect is reminiscent of the one at the famous megalithic tomb at Newgrange in Ireland. There at sunrise on the winter solstice (about 21 December in the northern hemisphere) the Sun illuminates the dark interior of tomb through a “roof box” above the entrance. It is not easy to be allowed into the tomb to witness the phenomenon: a lottery is conducted each year with over 28,000 people applying last year and only 50 names drawn. Interestingly, neither Alexander Macleay nor John Verge could have known about Newgrange as the effect was only rediscovered by Professor Michael O’Kelly in 1967.

As Newgrange is far away and difficult to get into at the Midwinter, try and make it to Elizabeth Bay House on the winter solstice in 2009, the International Year of Astronomy.