America's rapid adoption of LED lighting saves money and uses less electricity. But it's also making it harder to see the stars. 

Light pollution comes from excessive artificial light that causes the sky to glow and obscures the light of the stars, and the problem is growing fast. New research in the journal Science found the night sky is getting 10% brighter every year.  

Experts say much of that light pollution is driven by the growth of cheaper, cleaner and brighter LED lighting. 

"The most common kinds you see, the sort of bright white ones, are absolutely making the problem much worse," said Stephen Hummel, the dark skies senior outreach coordinator at the University of Texas' McDonald Observatory. 

A light pollution map of the United States shows the widespread nature of the problem. The eastern half of the United States is almost entirely blanketed by some level of light pollution. And while the night sky is hardest to see in big cities, the view of the night sky is also degraded in suburban and rural areas. 

"(Light) basically gets reflected from the sky and creates what we call air glow," said Ohad Shemmer, an astronomer at the University of North Texas, who studies black holes. "The Milky Way is gradually disappearing from view. Many of the fainter stars are disappearing."

Government regulation is driving the rapid switch to LEDs. In 2007, Congress mandated that all lightbulbs be three times more efficient. That policy finally took effect on August 1 of this year, effectively banning new incandescent light bulbs in favor of LEDs and compact fluorescents.  

But there are unintended consequences. 

Research shows too much light at night can interrupt our sleep cycle, potentially contributing to health issues like certain cancers and heart problems. It's also a major factor in the decline of insect populations which require darkness to navigate, and it contributes to the death of hundreds of millions of birds each year that fly into brightly lit buildings.   

The McDonald Observatory is in the Big Bend region of far West Texas. It's home to the Hobby-Eberly Telescope, the largest of its kind in the world. At night it collects the faint lights of outer space on an exceptionally large mirror. A dark night sky is essential to that work. 

Light bouncing off orbiting satellites threatens critical astronomy 01:56

"If the sky got too bright, eventually there would be no point in building big telescopes on the ground at all," said astronomer Steven Janowiecki, who is the telescope's science operations manager. 

To protect the night sky, the Observatory helped organize the Greater Big Bend International Dark Sky Reserve. It covers an area of 15,000 square miles across West Texas and portions of northern Mexico. The certification is granted by the nonprofit DarkSky, which has more than 70 chapters across the country. 

The reserve is a partnership of parks, communities and local groups that have all agreed to better lighting practices by swapping out their bright white LED streetlights for amber-colored ones that do not scatter as much light up into the sky and by installing covers that point light downward. 

The Alpine City Council unanimously passed an ordinance in 2021 regulating outdoor lighting. Nearly all the city's 200 streetlights have been updated from white to amber. The ordinance gives businesses and homes 5 years to convert to dark sky friendly lighting or face a daily fine of $50. 

"[Dark skies are] our product," said Chris Ruggia, the director of tourism for the City of Alpine. "It's the experience of coming here, and if we want that to continue, to provide some kind of prosperity in the community, we have to take care of it."  

Ruggia says there are local programs to help homeowners cover the associated costs of making the switch and that there has been little controversy around the mandate. But he anticipates that might change as the deadline approaches. 

"There's going to be some conversations that aren't easy, especially as the time limit runs out," he said. 

The American Lighting Association, which represents lighting manufacturers, acknowledges the problem of light pollution is "more extensive than originally thought."  In response, it says many of its manufacturers now make shielded outdoor light fixtures to direct light away from the sky. 

Light pollution readings taken across the reserve show the plan is working. Astronomer Stephen Hummel says there has been a 20% reduction in nighttime light pollution there since 2020.  

But it is not just small communities that are making an impact. Hummel points to big cities like Los Angeles, Chicago and Phoenix that are all swapping out overly bright streetlights for ones that are dark sky friendly. 

"The problem really is not money. It isn't infrastructure, really. It's awareness. Light pollution is completely reversible. It's one of the few kinds of pollution that you could solve immediately. You could flip a switch and fix the problem," he said. 

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