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A dim view of light pollution
Light pollution is a growing problem and it's not just astronomers who are suffering. Neil Hudson spoke to those campaigning to win back the night and introduce LED street lights in Leeds
Ancient mariners sailing distant seas swore by them. Long dead civilisations made dire predictions based on their movements, constructed megalithic monuments to mark their passage and wrote great myths about them.
The stars in the firmament have been an inspiration and source of wonder for mankind since the beginning of time but if you live in a city, it's odds on the only stars you'll be seeing regularly are the kind featured in celebrity magazines.
More often than not, the night sky is obscured by an omnipresent haze, the result of a thousand headlamps, street lights, undrawn living room curtains and floodlit cityscapes.
It's called light pollution.
The most one can expect of the night sky from an urban viewpoint is to pick out only the brightest of stars and planets.
But according to some, not being able to see the stars might be the least of our problems.
Some people believe a lack of proper night time darkness can have negative effects on human health and even cause cancer.
Solving these problems may mean changing the way we live in our cities at night.
Dr Paul Marchant is an astronomer and chartered statistician from Headingley, and a supporter of the British Astronomical Association's Campaign for Dark Skies.
He said: "Light pollution does affect our vision of the night sky and that isn't good for things like astronomy, but there's so much more to it than that.
"Night light affects animals and insects, our own vision and the way we perceive the world. There are studies going on into whether light pollution has an effect on our health.
"Life evolved on this planet with a dark side and a light side over about four billion years and in the last 50 we have created masses of light where it was once dark.
"Insects are particularly affected by this but some scientists also think it may also affect humans."
The American Medical Association passed a resolution about night time light pollution and went as far as suggesting it could damage the human immune system.
Part of its resolution said: "Many species, including humans, need darkness to survive and thrive. Light trespass has been implicated in disruption of the human and animal circadian rhythm, and strongly suspected (of causing] depressed immune systems and increase in cancer rates such as breast cancers."
In October this year, a street in Toulouse, France, became the first in the world to trial a new method of lighting, whereby lampposts are fitted with sensors which detect human body heat, increasing light output when people walk past, then dimming 10 seconds later, making an energy saving of 50 per cent. If the trial is successful it will be extended to cover the whole city.
Dr Marchant added: "From an astronomical point of view I find it harder to see things today which I might have spotted easily 30 years ago. I can remember seeing the Milky Way from home some years back but that would not be possible today.
"Similarly, I could see the Andromeda Galaxy with my naked eye from the local park but this is no longer possible, which is a shame. It is so distant that the light from its billions of stars takes two million years to reach us.
"To see the night sky, so majestic to behold, properly today you would have to travel far out of the city.
"I think it's important that we are able to see the night sky because it inspires an interest in people in all sorts of things, like our place in the universe, how stars work and so on. It has also been a massive influence on art, philosophy and poetry.
"There are things we can do, that councils can do to limit light pollution. I am not a great believer in the argument that having everything brightly-lit means we are safer.
"There is also an issue regarding the kind of lighting. Leeds Council is replacing its street lighting with new lights, which emit bright white light, which is composed of all colours of the rainbow, instead of the old sodium lighting. It's possibly more damaging to wildlife. The new lights tend not to be properly shielded; the light source itself should not be visible from afar."
Galloway Forest Park, Scotland may become one of only a handful of 'dark sky parks', if sanctioned by the International Dark-Sky Association in the next month.
It is one of the few remaining places people can go to get pristine views of the sky.
In July this year, the Welsh Assembly voiced its support for the Campaign for Dark Skies.
Leeds Council is about to trial a set of LED – light emitting diodes – street lamps in Armley. Some traffic lights already use this technology.
Coun James Monaghan, Lib Dem member for the environment and also a member of the Campaign for Dark Skies, who happens to have a degree in physics and astronomy, said: "The council is doing a lot to limit light pollution. We are about half way through a street light replacement programme, which has done a lot to limit the orange haze which used to emanate skywards at night.
"If you go up onto Otley Chevin now, for example, you can see the stars again, because the street lights have been replaced there.
"We are also in the process of replacing all our street lights to make them zero light polluting."
Coun Monaghan said another scheme about to be trialled in Armley was the use of LED street lights.
He said: "It's something the council is looking at. It could save us a vast amount in terms of energy because LEDs use far less than conventional lighting. It would also emit far less light pollution.
"At the moment we are about half way through our light replacement scheme in Leeds but if this trial is successful, I would like to see LEDs installed in the areas of the city which have not yet had replacements.
"I also welcome villages and hamlets who want to remain 'dark' and we are looking at ways of saving energy, by dimming street lighting between, say 1am and 5am, or turning off every other one.
"It's difficult because we have a certain amount of responsibility in terms of making people safe but we are addressing the problem of light pollution."
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Sunday 12 February 2012
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