Theft of the Night
For three million years, the human race has been able to look skywards on clear nights, and wonder at the starry vault, crossed by the Milky Way (our own galaxy seen from inside), the slowly moving planets and the occasional flash of a meteor ploughing through the atmosphere high above. These sights have been, since about 1950, gradually taken away from us by the baleful glow of wasted light, escaping from poorly aimed and often over-bright artificial lamps, to be scattered by airborne particles and aerosols. Over great cities, towns and even small villages, light pollution robs us, in the last millisecond of its journey, of light which may have travelled for hundreds, thousands or even millions of years to reach our planet.
There is a trend nowadays for road lighting to be better directed, not least because of the efforts of concerned bodies of astronomers such as the International Dark Sky Association and the British Astronomical Association's Campaign for Dark Skies. But most private lighting is not designed to restrict emissions to the premises to be lit, causing light trespass and nuisance to many non-astronomers, too. The fact that light is not legally considered a pollutant like noise and smoke means that victims of light pollution have little redress, and the stars have no protection in law. Here is a modern irony: spacecraft and telescope technology can deliver breathtaking views of the near and far universe, while the technology which lights our nights simultaneously draws a veil across the night sky.
Are we cutting ourselves off from the direct experience of the rest of the universe
Aims of the Campaign for Dark Skies
- Greater use of modern fittings which control the light emitted, to minimise sky-glow and light trespass.
- The right amount of light for the task, not wasteful over-lighting - Sensible wattages (a 40W light will adequately illuminate the average driveway and garden) up to a maximum of 150W;
- Controls on floodlighting of buildings, sports facilities, etc., with appropriate shielding, baffles and mounting adaptation causing lamps to shine preferentially downwards;
- Instructions about sensitive mounting, and information about light trespass and other possible adverse effects, in packaging of all exterior lights.
CfDS believes that:
- Astronomers have the same lighting needs as everyone else;
- Street lights should NOT be turned off, but well directed to illuminate just the street;
- Everyone should have the right to illuminate their premises at night if they so wish, as long as it does not intrude into neighbouring properties;
- Lamps used should comply with Institution of Lighting Engineers' guidelines (revised 1994), with 150W as a maximum value for typical domestic and small-scale commercial premises;
- In the absence of proper regulation of light, which is as much of a potential pollutant as noise and other impactors, retailers should take the lead in preserving a night-time environment showing a balance between good quality lighting and enjoyment of that night-time environment;
- The promotion of outdoor lighting should concentrate on aspects of visibility and careful lighting, rather than making debatable claims about crime deterrence and links between brightness and effectiveness;
CfDS points out that:
- Minimising light pollution saves precious energy resources. The amount of greenhouse gases released into the environment by power stations can be reduced.
- Well designed light sources emit little or no light above the horizontal. Unshielded lights may, depending on the design, emit well over 50% of their output above the horizontal.