Only one in a hundred people in western Europe can expect to see a truly dark sky when they look upwards at night, even on a clear night. The picture is the same in the USA. Many of us are being deprived of the spectacle of the Milky Way and some of nature's other night-time shows.
This is the result of light pollution. It spills from our towns and motorways and is revealed in the First World Atlas of Artificial Night Sky Brightness by Dr Pierantonio Cinzano of the University of Padua in Italy. The atlas will be published in the Monthly Notices of the Royal Astronomical Society.
"Large numbers of people in many countries have had their vision of the night sky severely degraded. Our atlas refers to the situation in 1996-7. It is undoubtedly worse today," said Dr Cinzano.
Over 99 per cent of EU US populations and two-thirds of the world's population suffer light pollution. In the regions of highest population in the affected countries, the sky is always brighter when there is a half moon. For some, the sky never grows darker than a "nautical" twilight - on a clear evening when the sun slipped below the horizon but night has yet to darken, a period of between 40 and 80 minutes.
To produce their atlas of sky brightness, Dr Cinzano and Dr Chris Elvidge of the National Geophysical Data Centre in Bolder Colorado used satellite images to show artificial lights on night-time Earth, combined with computer modelling.
"We take the satellite data and then use an atmospheric model to calculate the downward scatter of light back to the ground," Dr Elvidge said. The team are working on further improvements which take into account other factors such as terrain and air-moisture. They claim the adverse effects of light pollution have not been fully studied because, until now, the comprehensive data has been lacking.
It is not just star-gazers who may suffer from the lack of nocturnal blackness. Invasive lighting spilling from uncaring neighbours is a cause of stress. Add to this, environmental damage is caused by excessive demand placed on electricity to keep lights burning.
Darkness is a stimulant for some of the body's natural defences. Melatonin is a powerful agent in fighting disease such as breast and prostate cancer, and the body produces it in the absence of light.
Outdoor light pollution could be a factor but Dr Elvidge said: "Probably most people would be more affected by indoor lighting which is much stronger."
These islands fare better than most of Europe in terms of light pollution, according to the atlas. Most of England and Wales suffer light pollution up to nine times the natural levels, the west of Ireland and north-west Scotland have large tracts that are virtually unaffected.