Flagstaff, Ariz., has some of the most stringent “dark skies” laws in the country. These are laws that seek to reduce the level of nighttime illumination from streetlights and other sources. There is a compelling reason: high atop Mars Hill on the outskirts of town sits Lowell Observatory, founded in 1894 by Bostonian Percival Lowell. Lowell had been drawn to the American Southwest for its clear—and dark—skies, perfect for observing the heavens. In 1930, Clyde Tombaugh discovered the dwarf planet Pluto at Lowell Observatory. (When I toured the Observatory in 2002, they were having none of that “Pluto isn’t a planet” nonsense; alas, they lost that fight.)

In the years since Lowell first scoped out his site (as it were), as the 20th and 21st centuries became increasingly illuminated, communities like Flagstaff have pitched various battles with the sources of those lights, aiming to keep the night skies dark, not just for purposes of astronomy—be it professional or amateur—but for basic aesthetics and quality of life.

As lighted signs, digital signage, and electronic message centers (EMCs) become more prevalent, battles against nighttime illumination have been renewed, and city and town planners are starting to crack down on nighttime signage.