In Search of Bright Stars: Can the Bay Area Reduce Its Worsening Light Pollution?

Read a transcript of this episode here.

On a clear night, the greater Bay Area has some amazing dark skies with a chance to see glittering stars, constellations and planets — if you know where to look. But if you live in one of the area’s many dense urban centers, chances are that light pollution is blocking your view.

Bay Curious listener Bruce Wismer remembers what it was like to see the sky filled with stars when he was growing up in the small town of Forestville, in Sonoma County. “It’s just a sense of wonder to look at everything,” he said.

Now, from his home in Oakland, that once-majestic night sky view is filled with the glow of artificial lighting. What stands out the most to Wismer are the bright white lights on the eastern span of the Bay Bridge.

“Some lights point straight up, significantly increasing light pollution. Can they be easily redirected to reduce impact on the night sky?” asked Wismer.

Lighting the Bay Bridge

The eastern span of the Bay Bridge, rebuilt in 2013, is lit by 48,000 high-performing LEDs. Most of the fixtures point downward, focusing light directly onto the roadway. According to the California Transportation Commission (PDF) the design is intended to create “an even wash of white light across the roadway to provide safer driving conditions for motorists.”

But some of the light does reflect sideways and upward, adding to what’s called “skyglow,” one aspect of light pollution. The bridge also has decorative lighting that points upward, illuminating the suspender cables and the bottom of the main cable. So that might add to the bridge’s skyglow contributions.

“I think that when you don’t have that connection to the sky, you might not have as many opportunities to ask, you know, ‘What is this universe we live in?'” said Ben Burress, staff astronomer at Chabot Science and Space Center.

Even though some of the lights on the Bay Bridge can be redirected, a representative from the Metropolitan Transportation Commission says that while the agency is not indifferent to the interests of stargazers, the lighting on either span of the Bay Bridge is essential to the safety of the many thousands of drivers who cross the bridge each night.

So, it’s safe to say that we might not be able to see any change in the lighting on the Bay Bridge anytime soon. But of course, the bridge is not the only source of light pollution.

A brightening sky

Light pollution is getting worse every year. Typically, we rely on satellite data to measure brightness in the night sky. But new research suggests satellites may have been significantly underestimating the brightening of our urban light bubbles.

In a study published earlier this year in the journal Science, researchers found that the brightness of the night sky globally increased by about 10% every year between 2011 and 2022. The authors of the study analyzed data from over 50,000 naked-eye night sky observations from a citizen science project called Globe at Night.

By contrast, satellite measurements during the same time period found that nighttime glow from global light pollution increased by only 2%.

What could cause this discrepancy? In the past decade or so, there’s been growing popularity of the use of more energy-efficient LEDs. LEDs emit more blue light, which satellites aren’t able to detect. Additionally, satellites are more sensitive to light that is directed upward toward the sky, but researchers of the Science study found that it’s light directed sideways that accounts for most of the skyglow.

According to John Barentine, scientist, astronomer and principal consultant at Dark Sky Consulting, the study contains a caveat: He says it best represents areas with the most citizen-science participation — namely, places like North America.

Barentine noted that according to Globe at Night, from 2011 to 2022 the brightness of the night sky in the Bay Area increased by approximately 7% each year.

Turning down the lights

Increases in light pollution have been linked to a host of problems, including a detrimental effect on our circadian rhythms, and on ecosystems more broadly, by disrupting animal behavior.

“It’s bad for people’s health, and it’s bad for fish, and it’s bad for nocturnal animals because these species have evolved over millions of years to have darkness at night and all of a sudden we’re lighting up the night,” said Mark Buxbaum, an amateur astronomer and member of the Santa Cruz chapter of the International Dark-Sky Association.

There have been some recent attempts to rein in light pollution. In fact, California legislators passed a bill in September 2022 that would have required any buildings or facilities on state-owned land to make changes to reduce light pollution. But Gov. Gavin Newsom vetoed it, saying the costs were “unfunded and potentially significant.”

The same Assembly member who drafted that first bill introduced an almost identical one, AB 38, in December 2022. That one is working its way through the Legislature, but it could be years before we see any statewide change.

Buxbaum says his organization is pushing for change locally. He hopes Santa Cruz will implement an outdoor lighting ordinance to help curtail extraneous light from businesses and residences that add to light pollution. LEDs, he says, are also a culprit in the problem.

“Unfortunately, because they’re cheaper, people think that they can install excessively bright light at night under the mistaken assumption that more light is better,” said Buxbaum.

Individuals can help curb light pollution by making changes to their own homes. Anthony Barreiro from San Francisco Amateur Astronomers suggests turning off your outdoor lights when you’re not using them, closing your blinds when you have lights on inside at night, and getting the right light fixtures:

“You want light fixtures that are fully shielded so all the light is shining down on the ground where you need it, not sideways into people’s eyes or up into the sky. Warm-spectrum lights, meaning more amber, not so blue. Blue light scatters much more, [and] causes much more glare,” Barreiro said.

Hoping for a better view?

If you don’t want to wait for your town’s lights to dim to see the sky, there are places you can go to see the wonders of the cosmos. The general advice for success in stargazing is to find a dark spot, away from city lights. Once you’ve found it, give your eyes a chance to get adapted, and then look all over the sky.

Places like Henry W. Coe State Park in the South Bay, Mount Diablo in the East Bay, Mount Tamalpais in Marin County, and Sonoma and Napa counties in the North Bay are good for stargazing. On the Peninsula, the Santa Cruz mountains are a good spot.

If you’re willing to drive a bit further out of the Bay Area, you can head over to places like Pinnacles National Park, Death Valley, Yosemite or other national parks that usually have less light pollution. Or, refer to a dark sky map to find out where you’ll have the best view.

If you live in a light-polluted area, you can join a free telescope viewing at Chabot Space and Science Center in Oakland. On the Peninsula, there’s the Foothill College Observatory in Los Altos Hills, and in the North Bay you can go to the Ferguson Observatory in Sonoma County, which regularly has telescope viewings available to the public.

Or, you could join an astronomy club.

“There are actually hundreds of clubs of astronomy enthusiasts around the country. And in the Bay Area, we have a very rich collection of astronomy clubs,” said Andrew Fraknoi, an astronomer and board member of the SETI Institute (Search for Extraterrestrial Intelligence).

You can find other fellow astronomy enthusiasts on NASA’s Night Sky Network, many of whom host star parties and astronomy events, including camping trips.

Human connection to the stars extends far back in history, when our ancestors used them to create stories, measure time or navigate across vast swaths of land and sea.

“Astronomy is the science of our origins, because the material of which we’re made and everything that the Earth has produced has its ultimate origins in space,” said Fraknoi.