The difference dark makes

ID: 2282 | This file appears in: Dark Sky over Arches National Park
The difference dark makes
The National Park Service at Arches National Park measured the effects of artificial light glow in 2003 (upper half) and 2009 (lower half). The points of glow at the horizon illustrate how the light glow has lessened since 2003 but is still impacting astronomy in Arches. | Source: Arches_allskypan_NSNSD_NPS. September 21, 2009. Courtesy of the National Park Service, via NPGallery. https://npgallery.nps.gov/AssetDetail/DB81CF31-1DD8-B71B-0B0CE9B4ED2BA17F.
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Arches_allskypan_NSNSD_NPS. September 21, 2009. Courtesy of the National Park Service, via NPGallery. https://npgallery.nps.gov/AssetDetail/DB81CF31-1DD8-B71B-0B0CE9B4ED2BA17F.
"The difference dark makes" appears in: Dark Sky over Arches National Park