“If the stars should appear one night in a thousand years, how would men believe and adore; and preserve for many generations the remembrance of the city of God which had been shown! But every night come out these envoys of beauty, and light the universe with their admonishing smile.”

― Ralph Waldo Emerson

In mid-April (13-18 April) people from around the world will turn out their lights in an attempt to bring back the night sky for International Dark Skies Week. In most cities, the light pollution is so intense that the band of stars which stretches across our sky, we know only from books and pictures as the Milky Way. The International Dark Skies week was created to bring awareness to the loss of our starry night, and spread the word about how we can combat the effects of light pollution to bring back the dark night, not only for astronomy but for better managing our energy usage, protecting ecosystems and helping our own safety and health.

Light pollution interrupts natural circadian rhythms in humans, plants and animals. Melatonin is a hormone that is naturally released during prolonged periods of darkness. The presence of light can interfere with its production, especially blue light, like the light that comes from computer and phone screens. The International Dark Sky committee is proposing that red light is used, it’s at a lower wavelength, therefore, has the least impact on night vision and also decreases loss of melatonin. In humans, melatonin loss can lead to stress, weight gain, insomnia and depression. Animals decline in population due to interrupted mating cycles and migration patterns and predator and prey interactions for nocturnal creatures are disrupted. Light pollution also affects nocturnal insect pollination and hinders regulation of plant growth and root formation.

The International Dark-Sky Association and the Illuminating Engineering Society have combined forces to create a Model Lighting Ordinance that cities from around the world can use to improve health and safety in an energy efficient and eco-friendly way. In the US alone, wasted light costs $2.2 billion (USD) annually and releases 14.7 million tons of carbon dioxide. Dark sky friendly fixtures require a lower wattage because all the light from the fixture is pointed where it is needed, rather than half of the light going off in the opposite direction (the night sky). Cities like Calgary and Chicago have begun the switch to flat lens fixtures and have already saved millions of dollars in energy costs.

“Dark sky does not mean dark ground.” – The International Dark-Sky Association

Having lighting on the outside buildings offers greater security than having no lighting at all. However, having outdoor lights on at all times is simply not as good as using sensors. Action activated lights visually alert people to trespassers.

Glare is also a safety concern, and brighter lights often make environments less safe. Overly bright lights impair night vision and make places outside the illuminated areas harder to see. This is a major safety concern on the road as pedestrians crossing areas not directly under street lights are almost impossible to see.

There are some simple solutions that can help combat light pollution:

·         Shield lights to reduce glare and harsh shadows

·         Motion sensors to ’alert’ us to activity after-hours

·         Only use light when and where it is needed

·         Use timers and dimmers which will provide the necessary light to get the job done

·         Turn off lights when not needed

The International Dark-Sky Places Program cites communities, parks and reserves from all around the world that have made a substantial effort to preserve our night sky. Here in New Zealand we have the first dark sky reserve in the southern hemisphere and the largest reserve in the world! The Aoraki Mackenzie International Dark Sky Reserve has had a lighting ordinance incorporated into the Mackenzie District Plan providing lighting controls through most of the reserve since 1981. Since then, it has achieved the Gold Level status, meaning its skies are almost completely free of light pollution. The reserve is located around Mt. John and Lake Tekapo and includes the Mr. John Observatory. Mt John Observatory has several telescopes, one of which is the largest in the country, and this year marks it’s 50th Anniversary!

“To put it simply it is one of the best stargazing sites on earth.”
-Bob Parks, Executive Director, International Dark-Sky Association

The University of Canterbury uses the telescopes for research observing binary stars, extrasolar planets, the Galactic Centre, Magellanic Clouds, comets, near-Earth asteroids and stellar spectroscopy. Astro-tourism companies use the telescopes for night tours and also hand out everyday binoculars so that visitors can see astronomical objects that even highly technical telescopes cannot see in light-polluted areas.