Moonlight Tower, Detroit, 1900
In the early 1900s there was perpetual daylight over the city of Detroit. The Motor City had erected an extensive system of early street lights called Moonlight Towers--which stood nearly 16 stories high. These towers lit 21 square miles of Detroit and effectively turned night into day. Austin, Texas still has a few of these massive towers but they are now mostly gone from the American landscape, and were replaced by the ubiquitous shorter, less expensive utility pole. But since then we found out that artificial light at night is instead blinding us with light pollution. Excessive light at night impacts our environment, safety, energy consumption, and health. The American Medical Association has released a report affirming the dangers of excessive amounts of blue LED lights, which affect the circadian rhythms of humans and urban wildlife (AMA report available online at http://darksky.org/wp-content/uploads/bsk-pdf-manager/AMA_Report_2016_60.pdf).
The U.S. at night, 2012, NASA
Recent studies have shown that night lights are impacting urban vegetation as well. A paper entitled "Ecological effects of artificial light at night on wild plants" was published in the February 2016 Journal of Ecology by Bennie, Davies, Cruse and Gaston. In it, they find that lights at night change some plant species leaf and flowering characteristics, and can have significant effects on the health, survival and reproduction of plants. Many urban designers are now selecting night and security lights that have shields to light just the ground, rather than the entire sky. An organization called the International Dark Sky Association creates public awareness and assists conservation organizations with lighting management. You can find out more at http://darksky.org/
Moonlight Tower, Detroit, 1900
