A dark-sky preserve refers to an area, typically enclosing a park or an observatory, which limits light pollution unnaturally. By definition, light pollution refers to a lightening of the night sky as a result of artificial light sources made by man such as street lamps, car lights, and other sources. Consequently, the pollution causes a disruption in natural cycles which, in turn, hinder proper observation of the sky by astronomers. In different countries, the dark-sky preserves may be also be known as dark-sky parks or dark-sky reserves. However, the official term for these areas, as dictated by the International Dark-Sky Association (IDA), is a dark-sky reserve.
Dark-sky Parks In Europe
Zselic National Landscape Protection Area
This park lies in Somogy and Baranya counties of Hungary between Kaposvár and Pécs. The park has a relatively small approximate area of 32.19 square miles and is among the oldest on this list having been established as a dark-sky park on November 16, 2009. On the Bortle scale, it has a rating of 3 – 4. The hills of Transdanubia are among some of the sites within this park.
Pic du Midi de Bigorre
Also known as the Pic du Midi, this park in France is the largest on this list with an area of a massive 1200 square miles. The park is special in that it is the first dark-sky park to be established by the IDA in France and in Europe. Located in the Hautes-Pyrénées, its establishment as an International Dark Sky Reserve came back in December 2013. Minor planets such as 82896 Vaubaillon and others have been discovered by the observatory at the topmost part of the Pic du Midi de Bigorre Mountain.
Northumberland National Park
Possibly suggested by the name, this park is the northernmost one in the United Kingdom. With a span of 400 square miles, it is also the largest park in the UK on this list. In the north, it is located close to the Scottish border and Hadrian’s Wall. Establishment as a dark-sky park came back in 2013. The park has several sites such as the off-limits Otterburn Training Area as well as parts of the Kielder Forest.
Westhavelland Nature Park
Germany is represented by only this one park which has a respectable size of 508 square miles. While it is an older park generally, it was only established as an IDA International Dark Sky Reserve recently on February 12, 2014. The Westhavelland Nature Park is located in the German state of Brandenburg.
Kerry International Dark-Sky Reserve
Abbreviated KIDSR, this dark sky reserve is the only one from Ireland. The IDA designation is also a recent one on January 27, 2014, and has an approximate area of a colossal 27,000 square miles. The park has a Bortle rating of 1 – 3.
Measuring the Brightness of the Sky
The brightness of a night sky is measured through the use of a scale called the Bortle scale. The scale has nine levels. Different values of the scale represent different types of locations. For example, a naked-eye limiting magnitude (NELM) of between 7.6 and 8.0 is representative of an excellent dark-sky location. The lower the score means a brighter sky. In recent times, the scale’s effectiveness has come under criticism.