What is a dark sky reserve?
An area formally recognised for the quality of its night sky and protected by lighting policy — a designation that exists because artificial light at night has made genuinely dark skies rare across inhabited regions.
The problem it addresses. Skyglow — light scattered by the atmosphere — brightens the sky over and around populated areas, washing out fainter stars. Large proportions of the population in Europe and North America live under skies where the Milky Way is not visible at all, and many people have never seen it.
The designations, administered by DarkSky International:
Dark Sky Reserve — a dark core area surrounded by a populated periphery, where the surrounding communities have adopted lighting policies protecting the core.
Dark Sky Park — a protected public land area.
Dark Sky Sanctuary — the most remote and darkest category.
Dark Sky Community — a town or city adopting quality lighting ordinances.
What designation requires: measured sky quality; a lighting management plan; retrofitting non-compliant fixtures over time; and — significantly — public education and outreach, since the designation is intended to change behaviour rather than merely certify a condition.
What good lighting practice looks like, which applies far beyond reserves:
Shielded fixtures directing light downward, since light emitted above horizontal serves nobody and creates skyglow directly.
Only as bright as needed, and only where needed.
Warmer colour temperature. Blue-rich white light scatters more in the atmosphere and disrupts wildlife and human circadian rhythms more, which is why the shift to cheap high-colour-temperature LEDs made light pollution worse in many places even while reducing energy use.
Controls — timers, dimming and motion sensors.
Why it matters beyond astronomy: artificial light at night disrupts nocturnal animals, insect navigation and migration, plant cycles, and human sleep — and the ecological literature on this has grown substantially.
The unusual feature of light pollution is that it is one of the few forms of pollution that can be reversed instantly and at no cost, by switching a light off or pointing it downward.
In the UK, several national parks and areas hold designations.