The Big Picture
Light pollution, the excessive or inappropriate use of artificial light, effects us is so many adverse ways. It can have serious environmental consequences for humans, wildlife, and our climate and hinder the science of astronomy. Light pollution is a side effect of industrial civilization. The fact is that much outdoor lighting used at night is inefficient, overly bright, poorly targeted, improperly shielded, and, in many cases, completely unnecessary.
Light pollution has become so prevalent that a study documented in 2016, named "New World Atlas of Artificial Night Sky Brightness," showed that 80% of Americans can’t see the Milky Way from their homes (Falchi, F. et al, 2016). In Europe and the United States, 99% of the public can't experience a night sky without some artificial light in it. Light pollution is increasing world-wide at a rate of about 2% per year. In U.S. cities, this rate is as much as 6% per year. The image above shows trends in light pollution since the 1950's and projects it out into the near future. At the time this image was created, the rate of increase was less than recently determined.
Light pollution levels are classified by the Bortle scale, which measures the brightness of the night sky and how well the stars can be seen. It runs from 1 (excellent dark sky) to 9 (inner-city sky). In Oregon we are quite fortunate and have a very large area in the central and southeastern part of the state that is one of the darkest areas in the country. It has a Bortle Class rating of 1. Please refer to the map below. The dark blue indicates the areas of the country that have "pristine night skies" (Bortle 1 and 2).
Light pollution from cities and suburbs encroaches into nearby rural communities. To protect the magnificent dark skies of Oregon, we need to address light pollution from population centers as well as from within the rural areas themselves. Some think that the skies in our large cities of Portland, Eugene, Salem, etc. are never going to improve and will only get worse and ask "why bother?" Consider this: the City of Tuscon, AZ is similar in population to Portland, yet on any clear night city residents out in the fringes of the city are able to see the Milky Way. It wasn't always the case. How did they do it? They conducted community outreach and they instituted outdoor light rules and policies that provide for energy-efficient, well-designed lighting that provides both safety for its residents and protects the night sky. At IDA we say "Dark Skies, not Dark Ground."
