LIGHT POLLUTION

Since before the dawn of civilisation, it has enchanted and awed humanity. But the night sky, a majestic panoply of comets, constellations and galaxies, has now vanished for much of the population of Britain. An impenetrable fug of light pollution, caused by the huge rise in artificial lighting at night from street lamps, factories and airports, means that the heavens above are banished beyond the glow of neon and sodium lighting. Man has destroyed his view of the stars in a matter of decades. Astronomers from the Royal Observatory in Greenwich estimate that just 2% of the UK remains unaffected by the 'creeping cancer' of light pollution. Others estimate that at least 90% of the population is seriously affected by 'sky glow'.

In the UK, around 85% of the population live in urban areas where ubiquitous street lighting nullifies the glory of a cloudless night sky. "It takes the light from the rest of the universe hundreds, thousands, even millions of years to reach here. What a shame to lose it in the last millisecond of its journey," said Bob Mizon, co-ordinator of the Campaign for Dark Skies. Only the most isolated, thinly populated depths of Scotland and Wales and the heart of England's national parks remain truly dark. More than half the present generation of children has never seen the Milky Way, the luminescent band of interstellar gases and stars that stretches from horizon to horizon. But the real fear for astronomers is that hardly any of the next generation will be able to share in such celestial beauty.

The extraordinary expansion of light pollution is exposed in satellite images obtained by The Observer from the National Oceanographic and Atmospheric Administration (NOAA) in Washington. Taken in March 1984 and March 2003, they betray a startling expansion of light. England in particular is smothered almost entirely with the effect of outdoor lights. It reveals an island trapped in a bubble of light as billions of watts are poured into the heavens from signs, security lights, floodlights and 6.2 million street lamps. "A person in the UK would distinguish fewer stars in the sky than ever before. Even in a dark area they could probably observe the glow of a city on the horizon," said Ruth Hobson of the NOAA.

Yet during the Fifties only half the UK was affected by sky glow, according to experts from the British Astronomical Association. "There is nowhere in mainland Britain that is safe from light pollution," added Ruth, "Even in Orkney, the viewing is marred by the light from oil installations and offshore tugs. It only takes one large lamp to block out the view. This is a serious national problem, it's not just some astronomers whingeing." A recent atlas of 'artificial night sky brightness' by Italian scientists investigated how much of a country's population could not see the Milky Way. The world average was 21%. In the UK, this rose to 55%, one of the worst on the planet, and the trend is starting to affect wildlife. Glow-worms, which need a dark environment to thrive, have declined rapidly over the past 30 years.

Kate Parminster, chief executive of the CPRE, believes the next generation will be completely isolated from the rest of the universe behind a bank of artificial light. "We're fast losing one of the most beautiful and amazing things nature has to offer us," she said, "Already most of us live in places where light pollution is so bad that we'll never glimpse our own galaxy, the Milky Way." The growth of rural crime is partly blamed for the trend, encouraging the proliferation of motion-sensitive security lighting whose tendency to switch on with every passing cat lights up the most remote locations. Many are too sensitive and too bright.

But the loss of the night vista is slowly being taken seriously. A committee of MPs last month began an inquiry into the effects of light pollution. The astronomer Sir Patrick Moore welcomed it and told of the 'real menace'. Yet concern lags far behind that of our European neighbours, particularly the Czech Republic where, two weeks ago, astronomers pushed through the world's first countrywide law to reduce light pollution. In the meantime the Department for Transport will continue compiling an inventory of how many street lamps have a heavy hood to ensure that light is directed down on to the road.

The issue remains largely ignored among architects and urban designers, who believe the more light shines into the darkness the better. Controversial schemes include Barnsley's vast 'halo of light' as part of the town's regeneration plan. Dr Robert Massey, of the Royal Observatory, said, "It is a major heritage issue, yet it's very difficult to escape the problem. How many children have seen the Milky Way, one of the most magical things in the sky?" Scientists estimate that on a clear, dark night between 2,000 and 3,000 stars should be visible.