• The Milky Way galaxy looms over the McDonald Observatory in the Davis Mountains of far West Texas. - photo by Stephen Hummel

For the past century, some of the darkest night skies in the continental United States could be found in far West Texas. In the 1930s, the Davis Mountains were chosen as the site for what was then the second-largest telescope in the world. The McDonald Observatory was established as a preeminent institution for astronomical research and continues to play a vital role in, among other things, the discovery of distant galaxies and black holes. But this research relies on keeping light pollution at bay in a region where encroaching oil and gas development and the growth of nearby communities is increasing the lumens and scattering light, obscuring the night sky. 

These days, dark skies (meaning those luminous with the glow of stars, planets, and other celestial objects) interest more than just astronomers. The ability to view stars has become an increasingly rare resource across all inhabited areas of the planet. It is estimated that as many as 80 percent of people in the United States cannot see the Milky Way galaxy from where they live. Astrotourism is becoming a global phenomenon in such places as Chile, Namibia, and New Zealand. Nationally, Big Bend National Park has the lowest light pollution of any national park in the lower 48 states, making it a prominent destination for professional astrophotographers, amateur stargazers, and families eager to show their children the wonders of the night sky.

The team at the McDonald Observatory is seizing the moment to facilitate a continuous regional area of protected night skies that will be larger than any other on the planet. This dark sky “reserve” will help protect the observatory’s ability to do hard science — something enshrined (believe it or not) in Texas state law — but also functions as a draw for astrotourism and a call for awareness about the hazards of light pollution in cities and suburbs. 

Extending from north of Balmorhea down to northern Mexico, the proposed Greater Big Bend International Dark Sky Reserve — pending approval from the International Dark-Sky Association (IDA) — will encompass over 9.8 million acres and includes protected areas on the Mexican side of the Rio Grande opposite Big Bend National Park. The core areas include the national park, Big Bend Ranch State Park, the Davis Mountains Preserve, and the observatory itself. These areas already have stringent lighting requirements and are sparsely populated. But they are linked by peripheral zones that include the surrounding counties and towns, which have all adopted outdoor lighting ordinances in order to be considered part of the reserve. These ordinances include requiring shielded fixtures for both public and private lighting as well as lumen limits and low color temperatures for LED fixtures. 

Astronomers at the observatory have worked for decades with the surrounding counties to control light pollution, with varying results. In 2011, Governor Rick Perry passed legislation that mandated those counties adopt lighting ordinances to protect the night sky, clearing the way for the establishment of the reserve. However, the recent evolution of hydraulic fracturing and horizontal drilling has created a resurgence and expansion of oil and gas development in the Permian Basin and beyond. In 2016, Apache Corporation announced their Alpine High Play at the foot of the Davis Mountains and surrounding Balmorhea, promising major development due north of the observatory. The play fizzled out by 2020, but as many as 200 wells are currently active between Balmorhea and Pecos on land that was previously agricultural. 

The longtime dark skies coordinator for the observatory, William (Bill) Wren, worked with Apache to develop lighting practices that would help control light pollution at their wells and substation sites. Apache found that Wren’s suggestions also managed to reduce injuries and absenteeism while producing savings on lighting costs by reducing glare and wasted light. The practices were enthusiastically adopted by the company, which also encouraged their adoption by the American Petroleum Institute as a national standard. 

Wren’s concern for controlling light pollution for the observatory crosses over into other related concerns involving health, biodiversity, and resource consumption that make the issue relevant for everyone. According to the IDA, research suggests that exposure to artificial light disrupts sleep cycles by suppressing the production of melatonin, which induces sleep, boosts the immune system, lowers cholesterol, and helps the functioning of many organs. Resulting risk factors include obesity, depression, sleep disorders, and other maladies. The effects of artificial light on nocturnal ecology for plants and wildlife are just beginning to be understood, but negative consequences have already been identified for amphibians, birds, mammals, insects, and plants. The design of modern cities and suburbs is known to overpower the circadian rhythms around which humans and all other organisms have evolved, perhaps representing one of the most drastic changes in nature that humans have yet inflicted on the environment. 

That is not to say that humans do not require exterior lighting for mobility and safety at night. Dark skies advocates must routinely defend themselves against the perceived notion that they want to turn all lights off. The websites of both the observatory and the IDA provide extensive information on lighting principles and preferable fixtures that enhance visibility and safety while protecting the night sky. The basic guidance is that light must not project horizontally or upward toward the sky. The former leads to glare and a loss of visibility, and the latter is wasted light that scatters to block out starlight. LEDs pose a combination of problems. The first, ironically, is related to their efficiency. Due to the low cost per lumen, manufacturers are boosting the amount of available lumens per fixture to make them more attractive to buyers who continue installing them in traditional arrangements or spacing, leading to overlighting of exterior spaces. The other issue has to do with the availability of a range of color temperatures. Higher temperatures, essentially anything above 2700K, are not recommended for outdoor use because they scatter more readily in the atmosphere and block out starlight more than the cooler temperatures. 

With the widespread use of LEDs, light pollution is spreading at twice the rate it did previously with incandescent lighting. As a natural resource free to humanity and essential to its cultural and biological health, dark night skies should be preserved for those in rural areas and reclaimed for those in developed ones. Architects and developers can have a sizable impact on their communities by specifying dark-skies-friendly fixtures whenever possible and educating their clients about color temperatures and lumens. Also, cities and counties should be encouraged to pass lighting ordinances with enforcement clauses. 

Stephen (Chick) Rabourn, AIA, is an architect in Marfa.

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