Light pollution can be defined as the adverse effects of excessive artificial light. The name of the light pollution in cities is urban sky glow, and it is the overall brightening of the night sky in city settings. These types of environments would rate very high on the nine-level Bortle scale. A one rating is reserved for the darkest night skies, the best sites for stargazing. The scale was created by John E. Bortle and first published in 2001, although the accuracy of the scale has been debated.
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Key Facts In This Video
The first electric street lights appeared in the late 1870s. 00:30
An innate attraction to light can be so strong that it can mesmerize some song- and seabirds, who are drawn to searchlights on land. 05:08
Hundreds of species of night-migrating birds rely on constellations to navigate the night sky. 05:33