Since the first streetlight in the country illuminated Cleveland in April of 1879, the nocturnal glow of cities has brightened, reducing our view of the stars to just one percent of the twinkling universe that we would otherwise be able to see.
Any lighting that goes beyond what’s needed counts as light pollution, which by definition is something that nobody wants. One look at a strip mall or stadium parking lot confirms that our lighting habits go well beyond our practical needs. Neighbors commiserate over streetlights shining through the living room window or someone’s garage light intruding through bedroom curtains. Trespassing incandescence can disrupt good sleep and good health. Unwanted light also wastes energy and hikes up electric bills, but light pollution goes beyond human inconvenience and expense.
“I think for astronomers, the conversation is usually about access to the stars,” says Sally Oey, a professor in LSA’s Department of Astronomy. She acknowledges that yes, she’s an astronomer, so of course she would love for everyone to see the stars and care about science. “But for me, having considered all this in great detail over the past year, the benefits are so much more than that.”
A recent ecological study involving fake streetlights and night-vision goggles has shown that illuminated flowers get fewer visits from nocturnal insect pollinators and produce fewer fruits. When migrating birds travel past tall, lighted buildings, the birds tend to circle the buildings in confusion until they collide with windows or drop from exhaustion. Even salmon have trouble navigating to their egg-laying sites when bridge lights interfere with the night sky.
“That’s part of what really keeps me stoked,” Oey says. “For me, the environmental benefits seem almost more important than the astronomical ones. It seems as though every study is finding that there’s some kind of significant impact of lights on the ecosystem, and that’s why I’m alarmed.”
But here’s the good news. “Fixing the light pollution problem is relatively easy to do. Once you turn out or shield the lights, you’ve solved the problem,” Oey says. “It’s not like climate change, where even if we turn off all the carbon emissions right now, the globe still would continue to heat up for a while. With lights, as soon as you’ve covered them up, that’s it.
"Light pollution is easily reversible."
Instead of more lighting, Oey argues for smart lighting. In the past year, she’s rallied LSA students, faculty, Michigan residents, birdwatchers, architects, environmentalists, and others to join the Michigan Dark Skies group. The group calls for environmentally aware lighting, which can boost human health and safety, eliminate energy waste, and restore the ecosystem. Their major message: Illuminate only what you need and only when you need it.
“It started because I’d been teaching this course for upper-level astronomy majors at Kitt Peak National Observatory in Arizona,” Oey says. “We spend a month at Kitt Peak; it’s fantastic. As part of this course, we talk about what it takes to build and run an observatory, which includes what our responsibilities are to stakeholders of the observatory—and that includes the local communities,” she says.
Tucson is the biggest city near the Kitt Peak observatory, and Oey usually invites someone from the city government to talk about dark skies and the impact of the observatory on the local economy. She also invites someone from the International Dark-Sky Association, headquartered in Tucson, to talk with the students and city councilperson. “So the students get to meet these people and find out more about the whole dark-sky issue themselves.”
When the class returned to Ann Arbor in June 2017, Oey says, “there was this announcement in MLive that the Ann Arbor City Council just passed a resolution that they were going to spend a million dollars to replace the Kerrytown neighborhood’s globe lights with more of the same.
Attaching shields to streetlights significantly reduces light pollution. The lights on the far left carry no shields, while the lights on the right have full shields to ensure that artificial light illuminates only what we need: the street, not the sky.
“We’d just come back from Kitt Peak, where we heard about all these light pollution issues, so we were all fired up,” Oey says. She immediately wrote to her representatives on the City Council, and then she zipped off an email to the astronomy department: “Would anybody be interested in participating to help support a request that the City Council reconsider this?”
Dozens of faculty, students, and staff signed the letter. “It all took off from there,” Oey says, laughing, “because then the city actually replied. And once they replied, we were engaged, so then we had to do something about it!”
Instead of bright lights lining the streets and blocking the stars, the city now intends to replace Kerrytown’s globe lights with shielded LEDs that direct illumination downward, keeping the night sky dark above. The new bulbs will have a warmer, more natural white glow with lower wattage, rather than the more common, unnecessarily blinding, blue-tinted style.
Their quick progress with the city has inspired the Michigan Dark Skies group. They intend to continue advocating for best practices in public lighting and keeping light pollution to a minimum.
People sometimes resist the efforts of dark-sky advocates, arguing that lighting regulations can impinge on their personal freedom to buy whatever bulbs they want, light up their property, and keep their homes safe.
But Oey notes that although bright lights make people feel safer, we still can’t draw any reliable connection between well-lighted areas and lower rates of crime, even with decades of data from dozens of studies. Brighter lights produce murky darkness at their periphery that might actually help criminals hide in the shadows. Thieves might more easily peer in at the contents of parked cars when lights shine through the windows.
“We need people to understand why dark skies are necessary,” Oey says, “and that they’re a great benefit to everyone, including themselves.”
Oey wonders whether the freedom to light up the world has blinded us to our great loss of a competing freedom—to view constellations in the night sky and consider the scale of the universe, a loss that struck Oey on a recent night flight.
“I was on a 787 Dreamliner—one of the latest, most high-tech, most wonderful giant airplanes,” Oey recalls. “We settled in, and it was time for the flight attendants to come around and shut everybody’s window shade. I always pull mine back up again; I love to see the Earth from the sky and watch the clouds.
“But they didn’t do that this time. Instead, they pressed a button somewhere in the bowels of the airplane, and everybody’s electronic window shade just darkened. I couldn’t do anything about it. I had no more control over my window shade.
“I couldn’t see the stars. I couldn’t see the clouds. I couldn’t see the moon,” she says. “I couldn’t see anything.”
- “Astronomy Artist”
- “The Rise and Fall of Mercury”
- “Total Eclipse of the Sun”
- How to Science podcast: Episode 6 with Astronomer Tim McKay
- Learn About Supporting the Astronomy Department
- Michigan Dark Skies group homepage