Ian Cheney misses the stars. As a boy in Maine he designed his own telescope and mapped new constellations over the roof of his family’s barn. Now he lives in New York City, where eight million people share only a few dozen stars per night. Lately, he has been screening his film “The City Dark” under that blank, grey sky.
Cheney is young, almost defiantly young; his website features him photographed in Brooklyn neighborhoods in various intimidatingly hip hats. But he narrates the film, which was recently screened in a basement auditorium at Columbia University, in a pleasing, approachable way, with a matter-of-fact, not too preachy delivery reminiscent of that other American documentarian, Morgan Spurlock.
“The City Dark” examines the consequences of light pollution and disappearing stars. It touches on everything from nostalgia for the star-filled skies of Cheney’s childhood to scientists failing to see approaching dangers like asteroids or other space debris. Illuminating the streets has increased visibility and helped decrease crime in neighboring cities like Newark, New Jersey. But most outdoor lights are designed like a bare bulb, giving an equal amount of illumination in every direction, toward the ground where it is needed but also into the atmosphere, wasting energy and cloaking the night sky in an orange glow.
Light pollution, the excess light coming from cities at night, causes a variety of problems. Sea turtle hatchlings have evolved to know the sea as the lightest horizon, and are so disoriented by illuminated inlands that they many never make it to the water. In Chicago, about four thousand birds are injured or killed in building collisions during migration each year. Many bird species use the stars to navigate, but can’t see properly if the stars are obscured by light pollution coming from cities.
According to Cheney’s film, overnight shiftwork — in which the body is exposed to light through usually dark hours — is listed as a probable carcinogen by the World Health Organization. Shiftwork is associated with an increased risk of breast cancer, perhaps because light exposure suppresses the hormone melatonin, which helps slow down tumor growth.
Cheney is foremost an artist. His talent lies in piecing together beautiful images of astrophotography into a visual narrative, and filling that narrative with eccentric, charismatic people.
One of those charismatic people is Brooklyn based astronomer Irving Robins, director of the Astrophysical Observatory at the College of Staten Island, who garnered general chuckles for the line, “Americans are not known for their knowledge” and for his nickname for light pollution: “shmutz.” Chris Impey, an Arizona cosmologist, described the rare view of a truly dark sky. “It’s like you’ve smoked the very best kind of weed,” he said, followed by uproarious laughter and applause from the very sympathetic audience.
As the credits rolled, some enthusiastic audience members took star maps and headed up to the thirteenth floor roof for guided stargazing. It was, true to the film, less than stellar. There were only about ten visible stars, and one of them looked suspiciously like Jupiter. But the illuminated buildings looked fantastic.