A dark-sky preserve (DSP) is an area, usually surrounding a park or observatory, that restricts artificial light pollution. The purpose of a dark sky preserve is generally to promote astronomy. Because different national organizations have worked independently to create their programs, different terms have been used to describe the areas. This has led to confusion between the terms reserve, preserve, and park. The International Dark-Sky Association (IDA) chooses reserve to avoid confusion with park, when using the acronyms “IDSR” (International Dark Sky Reserve) and “IDSP” (International Dark Sky Park).
A falling star is captured in the dark southern night sky and the Milky Way from Strathmore Track show why this area is popular with astronomers, Warrumbungles National Park, NSW C1374E11 Australia.
In 1999, the first permanent preserve was established at Torrance Barrens in the Muskoka region of southern Ontario. Nevertheless, protection zones around observatories existed well before the creation of that preserve.
The IDA recognizes protected areas worldwide. The Mont Mégantic Observatory in Quebec is the first such site to be recognized (in 2007) as International Dark Sky Reserve. IDA has also recognized Natural Bridges National Monument in Utah as the world’s first International Dark Sky Park.
Canada has established an extensive standard for dark sky preserves that addresses lighting within the DSP and influences from skyglow from urban areas in the region. This was based on the work of the Royal Astronomical Society of Canada. There are no other established standards for dark sky preserves. Outside Canada, such designations are generally through self-proclamation. As a result, the validity of such a designation may be dubious. In some cases, dark sky preserves are neither dark nor protected.
It is generally understood that a Dark Sky Preserve, or Dark Sky Reserve, should be sufficiently dark to promote astronomy. However this is not always the case. The lighting protocol for a Dark Sky Preserve is based on the sensitivity of wildlife to artificial light at night (ALAN). The lighting protocol for the RASC is based primarily on wildlife sensitivity.