The ASNSW has as one of its major objectives the enjoyment of the night sky. With this in mind, the ASNSW tries to make its members and the general public aware of the effects of obtrusive outdoor lighting and light pollution problems in general.
The effects of light pollution impacts on astronomers more severely because of the way it diminishes the view of the night sky. In most major cities such as Sydney, the night sky is almost invisible to the naked eye apart from a few of the brighter stars. Light pollution, while not as well known as some of the more toxic pollutants such as oil, chemicals and plastic bags etc, is nevertheless still a major concern.
Can it be classed as a form of pollution? Most definitely YES! Light pollution can actually wash out the view from what is perhaps the greatest natural wonder of all – THE NIGHT SKY!
Light pollution is an insidious form of pollution because it disappears as soon as the offending light source is switched off and leaves behind no foul substance or filthy residue. The awareness of this form of pollution is becoming increasingly prominent in major urban populations as more and more people realise that they can no longer see the night sky. When New York City suffered blackouts in 2003, many people were left agog at the views of the night sky. Many were not aware that the night sky contained so many stars!
In Australia the effects of light pollution are not as severe as they are in countries such as the United States, however our cities and urban areas suffer greatly from the effects of obtrusive lighting. As you can see on the world map below, Europe and the USA along with parts of Asia are awash with lights, which greatly affect the enjoyment of the night sky in these areas of the planet.
There are three major forms of light pollution:
Light pollution has become a major menace to amateur and professional astronomers alike. However it can be minimised through the use of properly designed lighting that neither compromises safety nor impedes on the wonderful view of the heavens. Many communities around the world are becoming more aware of the problems associated with excessive and wasteful forms of lighting, and they are beginning to adopt ordinances in their areas to aid in the improvement and control of nightime lighting requirements.
Figure 2 (below) is a photograph of the night sky taken by ASNSW member John Sims. John was taking a wide field shot from the western observing field at Wiruna dark sky site, when the headlights of an approaching car ruined the photograph. The headlights caused the light green haze seen at top left of the photograph.
Have you ever been to a dark sky observing site such as the ASNSW's Wiruna property? If you have you would have also learned how to minimise light pollution at night. Members who attend Wiruna on a regular basis are aware of the need to shield any obtrusive lights, as it may ruin another observer’s view through their telescope. This is where some simple “Observing Etiquette” can save you from the wrath of keen deep sky observers.
Here are some simple things to consider:
Most of the electricity requirements for major Australian cities are met by coal fired power stations, or basically fossil fuels. Light wasted in a major city such as Sydney amounts to many millions of dollars. As well, many thousands of tons of carbon dioxide emissions are spilled into our atmosphere as a result of all this wasted energy. Stray light can also disturb the natural day-night cycle experienced by wildlife populations, causing distress and upsetting their balance.
Most of the poor lighting issues effecting Australia can be overcome by carefully considering the areas that need illumination, then finding properly shielded and energy efficient lighting fixtures to suit that situation. For example, streetlights can be replaced by full-cut-off fixtures, which ensure that light is directed downwards where it is needed most. They can also be fitted with energy-saving lamps. Lighting needed to illuminate signage should be directed downwards, not upwards into the night sky. Security lighting should be fitted with efficient lamps and shielded so that light is directed to the required area. Floodlights in residential areas can also be shielded quite easily to stop light trespass and light being emitted upwards. Home owners should avoid over-lighting an area where possible.
The outdoor lighting standards in Australia are surprisingly not too bad. Although some councils comply, most business premises and private institutions still have no interest in complying with the standards. Many countries around the world are increasingly adopting lighting controls, which carry with it vast savings in energy needs. A country such as Australia, which has a rich astronomical history and a strong base of amateur and professional astronomers alike, should be at the forefront of the major issue of light pollution.
Map images credit: P. Cinzano, F. Falchi (University of Padova), C. D. Elvidge (NOAA National Geophysical Data Center, Boulder). Copyright Royal Astronomical Society. Reproduced from the Monthly Notices of the RAS by permission of Blackwell Science.