Older street lights are a major cause of urban skyglow. In some instances, lighting schemes for streets, precincts and commercial premises are simply 'over the top' and indiscriminate to no overall gain and are simply wasteful. Illuminated signs and buildings contribute further as does uncontrolled and badly designed and installed domestic lighting. It affects every one of us, not just astronomers. Light pollution is a nuisance, it despoils the night time environment and places an unnecessary strain on precious natural resources.
Light pollution makes the night sky unduly bright and can prevent stars from being seen.
Astronomy from an urban site can be made impossible by the encroachment of light pollution. The night sky is a precious national and educational resource and is undoubtedly of great special scientific interest. To truly appreciate the night sky one may have to travel many miles from a built-up area to see a truly dark night sky. Most major astronomical observatories are now located in dark, sparsely populated areas and in some cases have been forced to move to other countries because of increasing light pollution from built-up areas. Excessive or bad lighting affects all living things.