Light is emitted from the Chicago skyline as seen from Lake View Beach, Indiana, the United States. Photos: TNS
Some of Drew Carhart’s earliest memories remind him of his love of nature. Not just trees, flowers or birds – but the stars, planets and galaxies visible in the night sky.
Fifty years ago, Carhart helped form the Naperville Astronomical Association, which now has two observatories, hosts regular “star parties” and teaches the community about astronomy and observing techniques.
But, due in part to light pollution and smoke from Canadian wildfires exacerbated by climate change, stargazing in the Chicago area is in danger. Some researchers estimate that North America experiences a 10% increase in light pollution – or the excessive use of artificial light – every year.
“You can’t overstate it – it’s like going deaf if you like music,” Carhart said. “It’s to the point where you can barely do it anymore.”
He and other enthusiasts are calling on the city and others to curb light pollution or risk missing out on starry night skies.
Growing up, Carhart said he learned the intricacies of the Milky Way from his suburban backyard in Naperville, Chicago. But slowly, the 64-year-old said, he watched the stars disappear. If someone were to visit his childhood home today, he said, they could count the number of stars they see on their fingers.
According to light pollution maps, viewing many celestial objects with the naked eye is difficult to nearly impossible in Chicago.
“The light pollution is tremendously worse. Out by Naperville, we could see the glow in the nighttime sky of Chicago off in the distance, but it only went a little ways up in the sky,” he said. “Over the years, we watched it get brighter and then extend overhead and all the way to the other horizon and just take over the sky.”
Anthony Harris, a Berwyn resident and the vice president of the Chicago Astronomical Society, said it’s difficult to see anything other than the sun, moon and planets in Chicago, and it takes longer to drive to more rural places where stars are visible than when he began stargazing 50 years ago. Harris said he believes one of the main culprits is the city’s streetlights.
As part of its smart lighting streetlight modernisation programme, Chicago began switching sodium vapour lights for more energy-efficient LEDs in 2017. Compared with sodium vapour lights, which give off an orange or yellow hue, LEDs emit a bright white light.
Since the start of the programme, more than 88% of the city’s streetlight stock has become LED lights, according to Erica Schroeder, a spokesperson for the city’s Department of Transportation. She said the programme has replaced more than 289,000 sodium vapour lights.
Schroeder said in 2021 the city cut its energy bill for streetlights in half, saving US$8.7mil (RM40.4mil). She also said the lights are on track to save US$100mil (RM464.8mil) over 10 years.
Utility company ComEd completed its own five-year LED Smart Streetlight programme in northern Illinois earlier this year, converting more than 130,000 ComEd-owned streetlights to LEDs. ComEd says the switch prevents more than 67 million pounds of carbon emissions from going into the atmosphere every year.
Some experts believe this shift will help people save money and cut carbon dioxide emissions.
But LEDs have their flaws, according to Ken Walczak, senior manager for the Far Horizons programme at the Adler Planetarium. Part of Walczak’s research involves designing and building instruments to monitor light pollution, including sending a high-altitude balloon into the stratosphere. He said every shining light contributes to sky glow. In major cities like Chicago, when there’s a lot of sky glow, it’s difficult to see celestial objects.
An LED streetlight (right) along Lake Shore Drive in Chicago, the United States.
LEDs emit more blue light, which travels at shorter wavelengths and higher frequencies, than typical bulbs. Walczak said the problem is that blue light scatters more in the atmosphere compared with other colours, creating something akin to a haze or a light fog.
“If you have lights which have a lot of blue in them, that blue light is contributing a lot to the glow in our night sky,” he said.
LEDs have been linked to a range of health issues, including sleep disruption as well as the prevalence of cancer, diabetes and obesity. They’ve also been found to alter the circadian rhythm and behaviours of animals. But the new streetlights have one advantage over older lights, Walczak said. They are focused downwards, which reduces glare.
The National Park Service suggests considering whether outdoor lighting is necessary, or if reflective tape or reflective surfaces could be used instead. Other sustainable outdoor light specifications, according to the Park Service, are LEDs at 2700 Kelvin. These lights emit a warm colour hue instead of blue or white.
Schroeder said Chicago’s streetlights are managed using a cloud-based monitoring programme and network of controller nodes that dictate when the lights turn on as well as their power output, voltage and wattage. She said these features allow the LED fixtures to turn on before sunset and turn off after sunrise.
She added that Chicago uses “soft white” lights, or ones at 3000K and that they are designed to “limit light trespass into people’s homes and the night sky”.
“The improved nighttime visibility that comes with the whiter, crisper, LED light improves traffic safety for drivers, pedestrians and bike riders,” Schroeder said. “This superior visual performance is largely the result of people being able to better distinguish colours at night.”
To reduce light pollution in Chicago, Walczak said he thinks the city should only use as much light as it needs. He suggests dimming the streetlights, which he said would also save on energy costs.
Walczak helped found a Chicago chapter of the International Dark-Sky Association, a nonprofit that seeks to preserve the night sky and limit light pollution. He worked with Wheaton to pass a residential lighting ordinance, which requires properties to limit the spread of their light fixtures.
“I think we’re learning more and more about the importance of the wavelengths of light and their impacts on our health and also the effects of light on flora and fauna,” said State Sen Laura Ellman. “With climate change, we want to try to minimise impacts wherever we can.” – Tribune News Service/Chicago Tribune/Rebecca Johnson
