Astronomy professor Sally Oey loves looking at stars in the night sky.

But in many places, the twinkling orbs are becoming increasingly difficult to see because of a unique form of environmental pollution: light.

Oey is tackling light pollution head-on as she works to raise awareness of the problem and help people realize the benefits of darkness. She is the founder of Michigan Dark Skies, a coalition that promotes darker skies in the greater Ann Arbor area.

Light pollution, or misdirected or excessive light, can wreak havoc on human and animal biorhythms, Oey said. It can also wash out starlight, making the stars that speckle the night sky nearly invisible to city-dwellers.    

“It’s really a fundamental change to the environment,” Oey said. “It’s a complete change to the ecosystem. It’s saying that the nighttime ecosystem will soon no longer exist.” 

Sally Oey (center front), professor of astronomy, with members of her 2017 Astro 461 class at the MMT telescope in Arizona. (Photo courtesy of Sally Oey)
Sally Oey (center front), professor of astronomy, with members of her 2017 Astro 461 class at the MMT telescope in Arizona. (Photo courtesy of Sally Oey)

Scientists say light pollution has increased globally over the last several decades as cities have become more populated and the cost of lighting has gone down, leading to increased consumption.

Oey said too much artificial light at night interferes with wildlife migration, feeding and sleep. Bright lights can disorient migrating birds and cause them to crash into buildings. Millions of birds die this way annually, according to the International Dark Sky Association.

In humans, artificial light at night can disrupt the circadian rhythm, a sleep-wake pattern governed by the day-night cycle. That can lead to interruptions in melatonin production, an important hormone for the body.

And when it comes to safety, Oey said there is no clear scientific evidence that outdoor nighttime lighting on streets and buildings deters crime.

“Humans are a daytime species. We’re biologically programmed to be afraid of the dark, and by default we react to light as a good thing,” Oey said. “It’s an unfortunate chauvinism of our species. But the good thing is that once (the problem of light pollution) is pointed out, most people quickly get it.”

Oey teaches a course in which she takes astronomy majors to MDM Observatory on Kitt Peak near Tucson, Arizona. A consortium of universities that includes U-M operates the observatory. There, the students spend a month gaining hands-on experience using powerful telescopes — and seeing firsthand the dramatic impact light pollution can have on their work.    

After returning home from a trip to the observatory in 2017, Oey and some of her students read about Ann Arbor officials approving the installation of globe-style LED streetlights in the city’s Kerrytown district. They wrote a letter asking the city to consider using streetlights that do not contribute to light pollution.

That letter, signed by dozens of members of U-M’s astronomy department, led Oey to found Michigan Dark Skies. It also sparked her efforts to help the city develop an ordinance to minimize the adverse impact of outdoor lighting.

Oey chairs a six-person working group that includes members of Ann Arbor’s energy and planning commissions. It drafted a proposed light pollution ordinance that would, among other things, limit the amount of light trespass at property lines, and require people who are seeking permits for new building and home construction to adhere to specific lighting guidelines.

The ordinance wouldn’t apply to U-M. However, Oey’s work has been warmly received on campus, with both the Central Student Government and faculty’s Senate Assembly passing resolutions encouraging the university to follow best practices for minimizing light pollution. Oey said she hopes university leaders will also approve measures to reduce light pollution on campus.

Oey’s interest in light pollution stretches back many years. She even wrote an essay about it as a high school student as part of her application materials for college.

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“I’ve been fascinated by astronomy for as long as I can remember,” she said. “There’s something irresistible about revealing the farthest and most exotic things we know. It really helps me understand our place in the universe.”

Today, nearly 200 people are involved in the Michigan Dark Skies coalition. They include U-M students, faculty and staff, as well as many community members.

Michigan has protected dark sky preserves in six state parks. It also has two parks — Headlands International Dark Sky Park near Mackinaw City and Dr. T.K. Lawless County Park in southwest Michigan’s Cass County — that are designated as dark sky parks by the International Dark-Sky Association.  

Oey said Michigan is one of the last places east of the Mississippi River that still contains areas with pristine dark skies, with most of them in the Upper Peninsula.

“We can still preserve it,” she said, “but we’ve got to act fast.” 


What memorable moment in the workplace stands out?

I teach a course that includes showing students the amazing historical celestial atlases in our Special Collections Library. One year, I mentioned to the then special collections librarian, Peggy Daub, how wonderful it was that we had three of the four most influential “Big Four” atlases. She said, “Well, then it would be really nice to get the fourth. Let me see if there are any copies available.” She went online and found that there was indeed one for sale for about $50,000. And she bought it!

What can’t you live without?

A good night’s sleep. When I’m not observing, that is.

Name your favorite spot on campus.

The historic Detroit Observatory on Observatory Drive.

What inspires you?

People who want to do the right thing. There are so many students, colleagues and citizens who work hard to improve our society and our planet. Knowing we can make a difference together is what inspires me.

What are you currently reading?

“The History of Java,” by Sir Thomas Stamford Raffles. Although better known as the founder of Singapore, he was the lieutenant-governor of the Dutch East Indies during its British rule, and he wrote an encyclopedic ethnography and compendium.

Who had the greatest influence on your career path?

My parents, who supported me chasing my dreams, no matter what they were.