Elizabeth Griffin made several excellent points in her letter about dark-sky advocacy in the May/June 2010 issue. However, I take strong exception to her suggestion that it may be time for astronomers "to step aside and let other interests do the running." While the inability to observe the night sky is of primary concern to astronomers, the most fundamental reason for eliminating light pollution is ecological. The problem is near-universal ignorance of the cumulative deleterious effects of light pollution on biological systems—as well as directly and indirectly 011 human health. This is a particularly propitious time for dark-sky advocacy by astronomers. The public is both concerned about anthropogenic contributions to plummeting biodiversity and accelerating environmental degradation and excited by the surge of recently discovered extra-solar planets, along with die debate about conditions necessary for life.
Our blue planet has been experiencing the rhythm of alternating light/dark (day/ night) since its formation .This fundamental condition engendered the evolution of endogenous circadian clocks in virtually all organisms.These include the cyanobac-teria (blue-green algae), which were the first oxygenic-photosynthesizing organisms and are thought to have been responsible for the "oxygen surge" that irreversibly altered the Earth's atmosphere some three billion years ago and stimulated the first explosive stage of biological diversification. Circadian biological clocks keep organisms' physiological-biochemi-cal-genetic processes synchronized to anticipate the transitions between day (warm, light) and night (cold, dark); circa-annual rhythms underlie appropriate seasonal adjustment of circadian rhythms. By altering the natural light/dark regime, artificial light at night can deregulate biological clocks and disrupt physiological rhythms, patterns of gene activity, behaviour, growth and reproduction, with cascading effects on food chains and ecosystems. Who better than astronomers to highlight the intimate association between the most enduring and the least mutable properties of Earth: its axial rotation and life itself.
While the standard arguments for light-pollution abatement (reduced energy consumption, demand for fossil fuel and cost) are undeniably important, they do not address the core issue of the damage to biological systems caused by disruption of the natural light/dark regime. The benefits to astronomers and ecosystems will remain modest, at best, without universal recogni tion of the right of unlit areas to remain dark.To achieve this will require proper installation of full-cutoff fixtures restricted to areas where ground lighting is needed for safety or specific activities.
Astronomers would most effectively facilitate the return of dark skies by helping to educate the public about the ecological damage caused by bad outdoor lighting and taking every opportunity to highlight the benefits of natural night lighting for environmental health along with the thrill of firsthand views of the night sky. With increased public awareness of the biological damage caused by light pollution and light trespass, residential areas are likely to become darker. Public pressure for environmentally and dark-sky-friendly lighting of streets and other public areas will influence retailers, motivate improvements in light-fixture design and, most important, instigate politicians to introduce effective bylaws for outdoor lighting in urban, suburban and rural areas.
Everyone shares a stake in reducing the deleterious effects of light pollution on wildlife, and hence ecosystems, not to mention human health, but only astronomers promote sensible outdoor lighting expressly for the sake of dark skies.
Dorothy H. Paul Victoria, British Columbia
VOLUME XVI, ISSUE 3
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