With Britain outlawing light pollution, Mary Russell looks at why it's OK to be in the dark
Does mention of Christmas bring on visions of flashing snowflakes and cute electric reindeer, the neighbour's garden with its floodlit manger and illuminated Santa plastered to the wall? Get rid of them, cries our inner Scrooge. Christmas lights waste energy. "No, no," says the cheerful opposition. Light is important, especially when the dark days of December make us feel down. We need more light, not less.
As any night worker knows, light deprivation can interfere with our circadian rhythm, causing our internal on-off switch to malfunction and go into jet lag mode. Scandinavians, know all about the effects of winter darkness, which is why they fill their houses with candlelight. However, the need for light has to be set against the fact that both winter and nocturnal darkness provide the rest periods the Earth and the human body must have in order to renew themselves.
So where exactly can we find this darkness that we need? It may come as a surprise to learn that, no matter how far we are from artificial lighting, we are never completely in the dark. "The earth glows at night," explains David Moore of Astronomy Ireland. "The sun pumps up atoms during the day and these re-combine at night to give off what we call air-glow."
In rural Co Donegal, your night-time view of the heavens will be majestic. In the Sahara, it will be biblical. But look at any global photograph taken from space at night and you will see huge and increasing areas of light pollution, which shows some us are living in a limbo of artificial daylight.Sadly, so polluted by artificial light is our world, just as some children have never seen snow, so many have never seen this magical air-glow.
In Britain this week, a Bill was published to make light pollution a statutory offence. Anyone who finds that artificial light from a premises is "prejudicial to health or a nuisance" will be able to complain to the local council. If nothing is done about it, the offender could be fined up to £50,000 (€72,308). Light pollution comes from the estimated 30 per cent of energy that is wasted, usually by excess light spilling on to pavements or leaking up to the sky."You're paying to light up the underbellies of seagulls and jets," is how Moore puts it.
Glare, light trespass and sky-glow are the unwelcome by-products of this pollution. The first happens when streets, motorways and roundabouts are dangerously over-bright. The second is when decorative and security lights leak into adjoining gardens and the last describes the orange reflection in the sky of an urban area.
"From the astronomer's point of view, light pollution here is not a huge problem," says Moore. "We are the least-densely populated area in Europe so you only have to drive 10 miles to get clear of Dublin's sky-glow, whereas you'd have to drive 100 miles to get away from London's." Nevertheless, lighting engineers are aware of the potential for pollution, which is why people like Ian Winning, senior executive engineer in Cork City Council's traffic department, are keen to cut down on the use of badly-shaded street lights.
"The thing is to put that into the design right at the beginning," he says.
In a recent project to light the 19th-century St Patrick's Church on the city's Glanmire Road, Cork City Council and the Friends of St Patrick's Renovation Committee erected low-brightness lanterns with well-designed reflectors, which provide lighting for people using the church and also illuminate the old limestone walls. In England, the Archbishop of York and Cardinal Cormac Murphy O'Connor called on churches to use low energy bulbs.
In Dublin, the two best examples of minimal-pollution street lighting are the newly restored Portobello Bridge, over the Grand Canal, and Wolfe Tone Park, close to the Jervis Street Shopping Centre. Gone are the orange sodium lights. Instead, there are clean perpendicular lines of lamp-posts furnished with well-positioned reflectors that cast light downwards, thus causing no glare. Paddy Craven, senior engineer in Dublin City Council's lighting department, is responsible for 45,000 street lights plus the 25 festive trees that appear throughout the city for Christmas. "We're phasing out the orange sodium lights and replacing them with light-emitting diodes, which are more efficient," he says. "We're also installing more uplights like the ones set into the pavement in O'Connell Street."
Two years ago, Armagh Observatory launched a campaign to persuade the city to be mindful of light wastage and set an example itself by using more focused lighting. Even more admirable is the Czech Republic, the first country to enact legislation to eliminate light pollution. But however much some may wish for less light, few will deny the pleasure of a cheerful Christmas tree or the reassurance of the candle in the window.
For myself, on a moonless night walk in the Sahara desert, I will always treasure the mesmerising sight of my own shadow, cast by the light of distant stars.