On cloudless nights in the Big Bend, the sky fills with the light of distant stars, revealing the Milky Way in startling clarity. The region is largely free from light pollution caused by street lamps and city lights—and astronomers want to keep it that way.
This corner of West Texas is home to some of the darkest skies in the country, and has become a go-to destination for both amateur stargazers and professional researchers over the last few decades. And while the Big Bend has been recognized for limiting light pollution, researchers with McDonald Observatory are looking to take their preservation efforts further by getting the region, including a stretch of steep mesas in Northern Mexico, recognized as an “International Dark Sky Reserve.”
The special designation, awarded by the non-profit International Dark-Sky Association, would recognize the area as one that has “exceptionally dark skies, and is promoting outdoor lighting practices that will keep them that way,” says Bill Wren, who works on McDonald Observatory’s dark skies initiative.
“It's thrilling,” Wren says of the region’s spectacularly starry nights. “It's a visceral experience.”
Ensuring the Big Bend skies remain dark has been part of Wren’s work for years now. He’s worked directly with oil and gas operations in the Permian Basin, where an increase in energy activity and the region’s growing population has led to a measurable uptick in light pollution.
Researchers like Wren have a particular interest in preserving dark sky over West Texas—it’s crucial to the research conducted at McDonald Observatory, perched atop the craggy Davis Mountains. The clearer the night—and the less light pollution obstructing their view—the better researchers are able to peer into the vastness of space.
The observatory is leading the application process, but Wren says the dark sky designation is about more than protecting astronomy research. “[It] could be a benefit for the region, not just McDonald Observatory,” he says.
During a virtual town hall this week, Wren, along with other dark sky experts at the observatory and at Big Bend National Park, mapped out what they see as the wide-ranging upsides that would come with the designation.
They say using shielded lights, which direct light toward the ground, and being mindful of the light’s intensity and how long it’s on is a money saver. They also say dark skies are a key contributor to the region’s tourism economy.
“Preserving dark skies, not only saves you energy money, but it can create money, because people come to the region to see the sky,” says Stephen Hummel, a dark skies specialist at McDonald Observatory. “Astro-tourism, especially in Fort Davis, is a huge driver of the local economy.”
Hummel points to the observatory’s popular star parties, which, pre-pandemic, would bring in an average of 100,000 visitors every year. “It's a great boost to the local economy,” he says.
Outside of a financial boon, mitigating the amount of artificial light shining into the night sky also helps to protect wildlife habitats and migration corridors in the Big Bend region, according to Hummel.
But getting widespread support for the kinds of lights and practices that benefit dark skies isn’t all that easy, says Wren.
He says for a lot of people “their initial reaction is ‘Well, they want us to turn the lights out and leave us in the dark with no safety and security,’ and so on,” recalls Wren. “And it's simply not true.”
“We are not against outdoor lighting at night,” he says. “This is about dark skies, not dark ground.”
Dark sky reserves, as defined by the IDA, consist of two main regions: a so-called core area, which meets the non-profit’s stringent requirements for sky quality and natural darkness, and a buffer area “ that supports dark sky values in the core and receives similar benefits.”
If approved, the Big Bend reserve would cover roughly 17,000 square miles, a stretch of land Wren says is “larger in size and scope” than the existing 18 reserves combined. The IDA currently recognizes both Big Bend National Park and Big Bend Ranch State Park as " dark sky parks." Together the two Far West Texas parks make up one of the largest areas of protected night sky in the country, according to the IDA.
The application process for becoming a reserve is intensive, according to Wren, and it could take a year or more to meet all the criteria set forward by the IDA.
“It’s a big elephant to eat!” Wren chuckles at the undertaking.
Part of the requirements to become a dark sky reserve includes cataloging outdoor lighting in the “core” of the reserve and bringing 90% of it into compliance with IDA standards. That means the region will need specific lights that have shielding so they shine downward and not into the sky. Outside of public spaces, which are covered by local ordinances that regulate outdoor lighting, Wren says buy-in from from private land owners is "strictly voluntary."
Another component of the application: actually proving the skies are, in fact, dark.
“We're trying to make a dark sky reserve,” says Stephen Hummel. “But in order for that, to really succeed, we have to kind of show that the sky here is truly dark.”
One of the ways crews from the observatory have been measuring the sky’s darkness is using special, cell phone-sized instruments to take stock of the night sky. Since last summer, they’ve recorded the sky’s quality outside Fort Davis, Alpine, Marfa and in the national and state parks.
“It's basically as dark as it gets here, and that's what we're trying to protect,” says Hummel.
“We're trying to make sure it stays that way. That the sky really is as dark as it is now, forever.”
The region’s longstanding lighting ordinances, which were first put in place to mitigate light pollution, give the observatory a leg up in its application process. Beginning in the late 70s, the state legislature enacted a bill allowing Big Bend municipalities the option of adopting lighting ordinances. More recently, former Gov. Rick Perry, signed a bill in 2011 requiring those governments to adopt practices to “minimize the interference with observatory activities caused by outdoor lighting.”
While those city and county ordinances give Wren and the observatory a “head start” on what’s required for the reserve, he says they need to be updated to “more accurately reflect current lighting technologies, like LEDs, and lighting practices.”
Updating ordinance language, measuring the quality of the nighttime sky, and meeting all the criteria for the reserve status won’t happen quickly. Although the region has light ordinances in place already, Wren says he hopes to raise public awareness of the benefits of dark skies.
“We're talking about a larger regional effort to keep the skies dark and keep the light on the ground,” says Wren. “This reserve idea is a vehicle to find some cohesion amongst these far- flung communities, to bring them together for a common cause.”
To see this common cause for yourself, step outside on a clear, moonless night, and look up.
Just remember to turn the lights off first.
