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"Pure Opinions"
Where did the night sky go?
 The milky way galaxy
These days we are lucky if we can see any but the brightest stars let alone the Milky Way. And it's not because the stars have dimmed in any way - its because the Earth has become a whole lot brighter. Air pollution has made the sky less transparent and more reflective, and lights from town and cities wash out the stars overhead - a phenomenon called sky glow.
I recently drove at night from Gisborne down the East Coast. From forty or fifty miles away I was amazed to see the glow in the sky of Wairoa - a small New Zealand town with a population of 9,000 poeple.
I know we light our towns during the night for safety reasons but perhaps this is something we have to rethink - because of course not only does this glow in the sky obscure the night sky, it uses plenty of electricity to light what are for the most part empty streets. Perhaps street lights could have motion sensors - movement of cars or pedestrians in the street would activate the lights to turn them on. That might even provide a deterrent for crime.
Recent thinking in architectural circles is that night lights around public buildings don't prevent illicit activities like grafiti but actually encourage them. Night lights provide the spray painters or night workers or burglers with light to do the job.
In Arizona there is an organisation called the International Dark-Sky Association. The IDA lobbies for dark-sky regulations and working with manufacturers to improve lighting products. In 2007 they gave an award to a newly built mall on the outskirts of Tucson, Arizona, that had considered the impact of its night lighting. It avoided "glare bombs" - fixtures that cast their shadows sideways over pedestrians.
Tucson's street lighting code limits the brightness of exterior fixtures and requires use of lights that are "fully shielded" - meaning that they cast no light above themselves. Calgary, Alberta, cut its electricity expenditure by more than two million dollars a year in recent years, by switching to fully-shielded, reduced-wattage street lights.
In these times when we are rethinking many of our accepted assumptions and behaviours, here's another one to add. But with a great spinoff - we get to gaze at the wonder of the night sky.
Posted by Robert Glensor on 31st August, 2009 | Comments | Trackbacks
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