Light pollution occurs when outdoor environments are artificially illuminated at night. Light pollution is caused by a combination of glare, light scattering, skyglow and misdirected or poorly placed lighting. These artificial lights' collective luminosity obscures the night sky and the naked eye's view of stars and other celestial bodies from the Earth.

Although it is most prevalent in urban areas, light pollution can extend as far as 200 miles from the light source. One can easily see the effects of light pollution by contrasting a view of the night sky in a rural area with one in a city.

Light pollution can also harm wildlife. It often disrupts the migratory patterns and schedules of birds and can misdirect newly hatched sea turtles trying to navigate from beaches to oceans. As insects are attracted to light, streetlights can interrupt flower pollination and can harmfully disperse insect populations. (Photo: Wikimedia Commons)