dark sky

The term dark sky refers to sky without light pollution, e.g., away from cities and other sources of visible light, thus ideal for astronomical observation. This aids astronomical research and is also of interest to amateur astronomers, who may travel to such a location with limited light pollution. Some sites (dark-sky sites) are set aside for this quality, often classified as a dark-sky park, a dark-sky preserve or a dark-sky reserve, where efforts are made to reduce and limit light pollution. Historical observatories have sometimes relocated from urban or suburban regions to such places. The region around an observatory may be declared to be a dark-sky site, much as the area around the Green Bank Observatory (GBO) is declared to be a radio quiet zone (the US's National Radio Quiet Zone, NRQZ). A current issue regarding light pollution is satellite constellations, which produce observation-challenges even in locations that have minimal light pollution from cities, etc.