NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 48 These two photo pairs compare natural and artificial light sources combined (top photos) and natural light sources only (bottom photos) over (A) the Henry Mountains in Utah and over (B) El Mirage Lake in California. The skyglow over the Henry Mountains is due to celestial light. In contrast, the skyglow over El Mirage Lake is nearly all due to artificial light.
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