1.  I am a retired teacher of physics and an active amateur astronomer owning two telescopes. During my professional career I naturally attempted to give students some appreciation of the Universe in which we exist. I also taught some astronomy as an optional part of the A-level physics course. I am involved with the Sidewalk Astronomers movement, which involves setting up telescopes in public places and inviting all and sundry to have a look at the sky. There is never any shortage of interest.

  2.  Today we have computer programs, slides, videos and even remotely controlled telescopes in distant parts of the world, but all these involve second-hand experience. We need to get across to youngsters that other planets and other galaxies are not just in books but can actually be seen from anywhere with the naked eye, binoculars or a modest telescope. Some years ago I remember suggesting to a class of—in today's terms—year nine pupils that their homework should be to observe an eclipse of the Moon which happened to be due that evening. "Please sir", piped up one young lady "is it on BBC or ITV?"

  3.  To suggest that students should go outside and look up, however, presupposes that there is something to see. When I was a schoolboy in the mid-50's I could go outside the front door on a clear moonless night and see the Milky Way. Now I have to go 60 miles into North Wales to do the same. From my garden in a North Liverpool suburb I can rarely pick out stars below third magnitude. I should be able to see stars three magnitudes (16 times) fainter.

  4.  Stars, however, are not the main problem. Using a telescope or binoculars enables you to see faint stars, because they make the point image of a star brighter relative to its background, while the main planets and the Moon are bright enough anyway. The real problem concerns subtle extended objects—the Milky Way, dark and bright nebulae, galaxies and meteor showers, together with the Aurora Borealis (which can be seen from dark sites in Britain more commonly than is generally realised) and the Zodiacal Light. The Andromeda Galaxy, for example, is several times the size of the full moon and should be a naked eye object, but from most sites—even through quite a large telescope—you can only pick out the bright nucleus. The North America nebula is another beautiful object that should be visible to the naked eye.

  5.  There are two separate problems— ambient light and sky-glow. Ambient light comes from streetlights, security lighting, house lights etc. Its effect is to reduce the sensitivity of the eye to dim light from the air. The eye never becomes properly dark-adapted, a process that takes about 30 minutes. Ambient light can be dealt with to some extent by shielding the eye with walls and hedges. Sky-glow is due to stray light going upwards from sources on the ground and being scattered by dust and water droplets in the air. Dim extended objects cannot be picked out against this glow and a telescope does not really help because it does not change the contrast. Sky-glow is mainly caused by direct light—the contribution of light reflected upwards from road surfaces etc is relatively minor.

  6.  Certain complicated techniques involving the combining of large numbers of images taken with CCD cameras attached to telescopes have enabled some amateurs to produce astonishingly good photographs of galaxies and nebulae under adverse conditions. The equipment involved, however, is extremely expensive and the sense of immediacy involved in simply looking through a telescope is lost. Some friends of mine have constructed—from scratch—an excellent portable telescope with a mirror 30 inches (76 cm) across. They go to a lot of trouble to make this monster available to the general public. The views, however, are nothing compared to what can be seen through the same instrument from an isolated dark site with only the sheep for company.

  7.  What can be done? To begin with there needs to be more control over domestic installations. The instructions provided with some security lights, together with their design, have at least begun to pay lip service to the avoidance of light pollution. This trend should be encouraged. It should only be legal to market lighting that fulfils set criteria and excessive stray light should be legally recognised as a nuisance in the same way as noise. Sensitive security cameras and non-optical equipment could reduce the dubious dependence on bright lights. Excessively bright lights and lights that send their energy uselessly up into the sky cost their owners wasted money to run and contribute pointlessly to global warming. Quite small design changes can make a big difference.

  8.  Secondly there is floodlighting. It is obviously necessary to illuminate large public areas such as sports arenas, car parks and work areas. The design of the lighting, however, needs to be controlled so the light is thrown downwards and not sideways and upwards. As well as helping astronomers it is more economical in the long run. The floodlighting of buildings may be justified on special occasions, but as a general policy it is extremely wasteful and causes sky-glow. Cannot people see them during the day? How do religious bodies justify stressing the beauty of man made buildings while hiding the beauty of the firmament?

  9.  It is pleasing to note that many streetlights on main roads are now well designed so that their light is directed downwards. They are more comfortable to drive under—older lights send out light directly into drivers' eyes, dazzling them. The design of many lights on minor roads, however, is appalling—you are dazzled if you try to look up while the actual lighting at ground level is patchy. Obviously it would be prohibitively expensive to replace all these lights in one go, but where replacement does occur it should be with an approved design.

  10.  Nocturnal advertising in the form of neon, floodlights and lasers should be discouraged and rigorously controlled. Local initiatives to attract tourists—"city of light" and so forth—and new architectural projects should be strictly monitored in terms of light pollution.

  11.  To sum up, we all need light but it should only be allowed to fall where it is needed and not allowed to become a nuisance. The night sky is undoubtedly "an area of outstanding natural beauty", an unrivalled educational resource and essential to an understanding of the human condition. It is a part of our children's birthright. If it were a rural landscape or a great building it might be treated with the respect it deserves.

  12.  What policy should be adopted? Regrettably, for economic reasons improvement must be gradual. It does, however, need to be monitored and realistic targets need to be set and achieved. Perhaps a Star Tsar is needed. Quite simple tests could be devised. A network of observers might record whether or not the Milky Way and certain fainter stars are visible in good conditions from designated sites. This could be repeated annually. Designing measuring techniques to assess sky-glow should not be too difficult. Aerial and satellite photographs taken at night give a good indication of the level of pollution and can be monitored over time. Proper lighting regulations need to be drawn up and enforced—councils need to have someone responsible for this and adequate finance will be required. An unpolluted sky should be a matter for civic pride.

  13.  As an interim measure certain spots around the country—reasonably accessible from the main cities—could be chosen, basic facilities provided (car park, toilets—possibly more, such as a visitors' centre) and designated as observing points. There could then be an assault on sources of light pollution for some miles around.

  14.  Finally it should be remembered that light pollution is not just the concern of astronomers. It also has implications for public health (sleep deprivation), animal life, plant life, road safety, aerial navigation and—in terms of the waste of fuel burned to produce stray light—for global warming.

April 2003