There’s a good chance the night sky looks very different from the way your grandparents remember it, and those changes aren’t a good omen.
Light pollution wreaks havoc on biological systems, altering the circadian rhythms which guide the 24-hour cycle of sleep for most life on Earth, and for as much as 80 percent of North America’s population, it hides what was once a constant in the night sky: the light of the Milky Way.
“Light pollution is a form of pollution that is a form of environmental destruction that is absolutely on par with air or water pollution,” said John Barentine, International Dark Sky Association program director.
Most life on Earth is dependent on sunlight, he said, and throughout Earth’s history, life forms evolved to respond to the natural periods of light and dark.
“When we use electric light at night outdoors, we’re putting light into the environment during a period of time of day when our bodies don’t expect there to be any,” Barentine said.
Since many systems within plants and animals depend on this demarcation of light and dark, he said, alterations to the natural light cycle can have negative, and sometimes deadly, repercussions over long periods of time.
“Disability glare, eye strain, loss of vision and stress that people get from glare and spillovers are worth mentioning,” said Meghna Tare, Institute for Sustainability and Global Impact executive director. “Our eyes naturally adjust during day and night so we can see things properly. Too much light can harm our eyes and also harm the hormones, such as melatonin, that do this job.”
But light pollution is also stripping humanity of a sight that provided a sense of awe throughout history, Barentine said.
“We know that the Milky Way and the stars have been a source of inspiration for humans, almost as long as we’ve had an identity as humans,” he said. “Any time that we lose touch with an element of nature like that, I think that we lose something important about what defines us as human beings.”
The new study found the Milky Way is hidden from more than one-third of humanity, including 60 percent of Europeans and nearly 80 percent of North Americans. Along with the ecological consequences, the deprivation of humanity’s ability to see our own galaxy could have a potential impact on culture “that is of unprecedented magnitude,” the study said.
Light pollution creates a haze in the night sky known as skyglow, Barentine said, and light emitted from the ground interacts with particles in the air and is scattered back to the ground. Effectively, the sky glows and light beyond the atmosphere from stars and the Milky Way must make its way through that signal.
“To say that light pollution is benign is just contradictory to the facts,” Barentine said.
There are changes that can lessen the impact of light pollution, while still ensuring safety and convenience, Barentine said.
“Talk to your landlords,” he said. “Look at the lighting on the buildings and houses where you live and see if there’s an opportunity to improve.”
Removing unnecessary lighting, adding shields to outdoor fixtures that direct the light downwards and setting motion controls to activate light when movement is detected can have a big impact, he said. But the simplest solution may be to turn off lights that aren’t needed.
UTA considers the impact of light pollution around the campus, and works to ensure safety while also protecting against environmental impacts, Tare said.
“For a campus with so many students, it is necessary to have lights for the safety of the student population,” she said. “We install energy efficient LED light bulbs and motion sensors so that the lights are off when there is no one in the room.”
Barentine said Dark Sky International is by no means advocating colleges go dark, but instead that businesses and individuals consider the impact of electric lighting and institute initiatives to curb the effects of light pollution.
While Arlington does not provide the best view of the Milky Way, there are places within driving distance of UTA that offer unobstructed views of the galaxy, he said, including Enchanted Rock State Natural Area, west of Austin, and Copper Breaks State Park, west of Wichita Falls.
“Having an opportunity to go to the dark places that are preserved is important,” Barentine said. “The hope is that people start thinking, ‘Why can’t we have this where I live?’ And that’s the thought process that we hope starts people on the path of making a difference.”