Moving to the dark side

Thu, Sep 20, 2012, 01:00

ASTRONOMY IS A FOUNDATION of science. The desire to understand the skies was common to every ancient civilisation, from Mesopotamia to our own, as seen at the magnificent Newgrange.

Astronomy informed much of the mythmaking and storytelling that are the basis of our oral and written cultures. Yet the sense of wonder generated by the stars has largely been lost on present generations. The advent of mass artificial lighting in the early part of the 20th century has made our streets safer but obliterated the night skies for most of us.

The majority of street lighting diffuses the light not only downwards to the pavement but also upwards. The effect of thousands of street lights is to create the familiar orange “skyglow” that hangs like a luminous fog over our towns and cities. Misdirected light not only destroys the view for astronomers but also leads to huge wastage of energy and is unnecessary, given modern design options.

Most urbanites cannot see the Milky Way, the wondrous band of stars that is visible directly overhead in the summer sky. Nor can they see Andromeda, our nearest neighbouring galaxy and the farthest object from us visible to the naked eye.

A survey in the UK last year illustrated how completely the night sky has disappeared for most people. In winter the magnificent constellation of Orion burns through the worst light pollution. In a dark sky one should be able to see 30 stars within its boundaries. Only 2 per cent of people in the UK could see 30 stars.

One place that is bucking the trend is Galloway Forest Park, in Dumfries and Galloway, in the southwestern corner of Scotland.

Motorists who take the ferry from Larne to Cairnryan (it used to be Stranraer) frequently skirt the edges of the park on the way to somewhere else, but if you are not in a hurry and the skies are due to be clear it is worth spending at least a night.

In 2009 the forest park was the first place in Europe to be designated a dark-skies park by the International Dark Skies Association, an organisation set up in the United States to highlight the problems of light pollution and to attempt to preserve the night sky where possible.

When we visited earlier this year the skies, luckily, were clear on a couple of nights; unluckily, there was also a full moon. With no light pollution to counter its effects, it bathed the whole area in a blue brilliant enough to read a newspaper by.

To qualify as a dark-skies park, villages on Galloway Forest Park’s periphery had to alter their lighting to minimise light pollution, amenities had to be in place to accommodate astronomers and there had to be a public education dimension to it all. The effects have been startling. Seventy-seven per cent of tourism businesses in the area have reported an economic benefit from the dark-skies designation.

Such a park ought to be replicable here. Ireland is a relatively underpopulated country, and night-time satellite images already show swathes of the country in relative darkness.

Brian Espey, a professor of physics at Trinity College Dublin who chairs the astronomy and space committee of the Royal Irish Academy, says southwest Kerry is being targeted as a location for a dark-skies park in Ireland. The area around Waterville, which already attracts many tourists, would be ideal, he believes. South Kerry Astronomy Group highlighted the pristine nature of the skies at the Cill Rialaig artists’ retreat, on Bolus Head, on September 12th.

“People are realising that there is competition for markets out there. If you have got an edge in any direction it helps,” he says. “The difficulty is setting up a dark-skies park. That’s the hard part. Once one is set up it can be used as a template. Luckily, the area we are working in has only 18 street lights.”

Espey says the sky glow from Dublin is so bad that nowhere in the Wicklow Mountains within 60km of the city would merit a dark-skies designation.

Dr Ray Butler of NUI Galway says the west coast, particularly the western parts of Donegal, Mayo, Galway, Kerry and Cork, would be the best places; he points out that Connemara is especially suitable, as it is both a tourist destination and relatively isolated. He, too, believes Wicklow is probably too close to Dublin for a dark-skies park, but at least the light pollution is to the north.

“The worst position to be in is when there is a major source of light pollution to the south of your location. Many of the most interesting things in the sky never get very high above the horizon, and they peak in altitude when due south. So Louth and Wicklow may be equidistant from Dublin, but I wouldn’t locate an astronomical facility in Louth.”

Prof Mark Bailey, the director of Armagh Observatory, says the island of Ireland is better placed than most places in Britain to have a dark-skies park, which he believes can be combined with Ireland’s strong astronomy heritage to make a compelling tourism package. He believes Beaghmore, in Co Tyrone, where there are ancient stone circles, would be an ideal site in Northern Ireland for such an observatory.

Ronan McGreevy was a guest of Visit Scotland;

Let there be (less) light

Becoming a dark-skies park is not just a matter of finding a pristine location and looking for a designation.

The park has to be accessible at night: there’s no point designating a place that is inaccessible to the public.

Galloway Forest Park squares the circle of being both isolated and accessible. It is only two hours from the cities of Glasgow, Edinburgh, Newcastle and Belfast yet is sufficiently unpopulated to guarantee pristine skies.

Indeed, the skies are so pristine that they are at the outer limits of darkness. On a scale of 1 to 25 – 25 being total darkness – they are at 23.8.

The brightness of celestial objects is known as their magnitude. Andromeda has a magnitude of 3.5 and will not be visible in light-polluted skies; at magnitude 5.72, M33, also known as the Pinwheel galaxy, is at the outer limits of what is visible in the darkest skies.

To achieve the gold standard like Galloway, objects down to magnitude 6.8 must be visible from your location. This would allow the Milky Way to be seen in all its glory.

All lighting within the park must conform to standards and must be fully shielded, so the light is not dispersed upwards. Forty-seven residents living near Galloway Forest Park agreed to change their lighting to help achieve the designation.

A dark-skies park must also educate the public about the glories of the night sky and the effects of light pollution.

Events must be held in the park, and the park must be approved by at least two State agencies, such as a local tourist board or local authority.

Galloway Forest Park remains the only park in Europe with a “gold” designation. Zselic National Landscape Protection Area and Hortobagy National Park, both in Hungary, have achieved the silver standard, as they have slightly less pristine skies.

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