When stars disappear…
One of the negative effects of industrialization on human activity and the environment is the production of excessive light. It may seem strange, but excess light is a form of pollution, particularly at night. The negative effects of light pollution impact many fields of study, including economics, ecology and, of course, astronomy.
Most people do not consider the surplus of artificial light as a form of pollution because it is not permanent; all we must do is collectively turn out our lights to make it disappear. In reality, however, such a solution is unrealistic because our society needs artificial light to function.
Light pollution is mainly caused by lighting systems that are misdirected, excessive, inefficient or unnecessary. Most light pollution is found in urban settings where artificial light sources are numerous. In these areas, light sources may be partly directed towards the sky, or downward directed light may be reflected upward. Light is then dispersed by layers in the atmosphere and produces a glow that diminishes the darkness of the night sky. In large Canadian cities, more than 95% of stars that can normally be seen with the naked eye are no longer visible.
Unexpected negative effects
From bacteria to the stars
The negative effects of light pollution on human activity are numerous. From an economic point of view, for example, the use of excessive lighting or unnecessary lighting constitutes a waste of energy that is costly to both the individual and to industries. In Quebec, the cost of “lighting the sky” is estimated at 45 million dollars per year. On a larger scale, excessive lighting can have an impact on global climate change if the required electricity was generated by burning fossil fuels.
Wildlife and plants are also affected. For example, nighttime lighting can confuse animals that migrate (like moths and migratory birds), can modify predator-prey relationships, and can even alter competitiveness within the same species.
It is even possible for entire ecosystems to be affected. In lakes, for example, zooplankton may stop feeding on algae if nighttime lighting is too strong. The result is excessive algae growth that eventually decomposes and causes an increase in bacterial activity. This leads to oxygen depletion in the lake, and many species of invertebrates and fish then die by asphyxiation.
In astronomy, light pollution is a real and pressing problem. It diminishes the contrast between the dark sky and celestial sources of light, which makes it harder to see the stars. For the amateur astronomer, it is a major problem because access to a truly dark sky is increasingly difficult to find.
The increasing inaccessibility of the starry sky is unfortunate because it has become evident that amateur astronomy plays an important role in the development of scientific interest among young people. In 2003, the British government even acknowledged the link between a reduced interest in the sciences and an increase in light pollution!
For professional astronomers, artificial light is undesirable because it interferes with the collection of data. This is why new observatories are built in isolated regions.
Fighting light pollution
A simple gesture with big returns
Hubert Reeves talks about light pollution.