In July 2020, the University of Texas McDonald Observatory went public with an ambitious plan to create an International Dark Association (IDA) certified Dark Sky Reserve: The Greater Big Bend International Dark Sky Reserve (DSR). The proposed DSR spans Northern Mexico, Southwestern Texas, and New Mexico and will protect and improve night sky viewing for nearly 10 million acres – more precisely 9,737,828 acres. Already, 16 local, state, federal and private land managers, agencies, and entities have signed on to help ensure that world-class quality night sky conditions endure in the Big Bend for future generations to enjoy.

According to the IDA (, a Dark Sky Reserve is “a public or private land possessing an exceptional or distinguished quality of starry nights and nocturnal environment which is specifically protected for its scientific, natural, educational, cultural, heritage and/or public enjoyment qualities.” The Big Bend DSR will become Earth’s most recent – and largest – protected night sky region, polishing the region’s global reputation as a destination for scientific discovery, astro-tourism, and top-quality night sky experiences. What’s more, DSRs generate important ecological and human health benefits.

Dark Sky Reserves consist of a “core” area meeting minimum criteria for sky quality and natural darkness, and a peripheral region which supports preservation in the core. The core of the proposed Big Bend DSR is “Texas Big:” At 1,253,351 acres it includes Big Bend National Park, Big Bend Ranch State Park, the Chinati Mountains State Natural Area, Nature Conservancy Davis Mountains Preserve, and the McDonald Observatory. These publicly and privately managed lands have already secured IDA certification by retrofitting light fixtures with night sky friendly technology and implementing night sky friendly practices. The peripheral region will add an additional 8,484,477 acres to the Big Bend DSR. IDA certified places also advance night sky conservation through outreach and interpretive activities, showing how night sky friendly lighting improves illumination, visibility, safety and the enjoyment of nighttime phenomena and nature experiences.

Places like the Big Bend International Dark Sky Reserve demonstrate how improved night sky quality can be achieved at scale. The proposed DSR will protect and improve night sky quality for a land area exceeding the size of Delaware with “win-win” results, reducing exposure to artificial light pollution while yielding economic, ecological, human health and safety benefits. 

Binational, Regional and Local Partnership

“To achieve the creation of the Big Bend Dark Sky Reserve will involve a tremendous amount of cooperation across county, state and national boundaries,” says University of Texas Dark Skies Initiative Director Bill Wren. Known affectionately as “The Godfather of Darkness” for his decades of work to promote and improve night-sky friendly lighting practices across the Big Bend, his achievements in this arena are not insignificant. University of Texas, Texas A&M, and collaborating international researchers rely upon quality night skies at McDonald Observatory for astronomical observing, scientific discoveries, and visitor programs. In support of this, Wren and others worked with the Texas General Land Office and petroleum industry to transform how oilfield operations and transportation can safely and effectively illuminate these 24-7 activities while preserving nighttime sky quality. One wonders: If the oilfield can do it, can the rest of us?

Wren emphasizes that night-sky friendly lighting practices improve illumination and security after dark. “In fact, we can all improve nighttime visibility and safety by reducing glare, directing light to where it is wanted. It’s win-win.” 

The Economics of Night Sky Friendly Lighting Practices

McDonald Observatory near Fort Davis, Texas hosts nearly 100,000 visitors annually for Astronomy and Solar viewing programs. A growing roster of Big Bend lodging, food service and other hospitality entities cater to amateur and professional astronomers, astrophotographers, and members of the public in search of high-quality night sky experiences. Their lodging stays, restaurant, grocery, fuel, and tourism generate substantial revenue. For example, if each of those travelers spent only $50 per visit, it would contribute $5,000,000 to the local economy. Include 8.25% sales tax paid on incidental purchases, or a 15% lodging tax to whatever base revenue is generated, to envision how the economic benefits of high-quality night skies quickly add up.

One example of how high-quality night skies are a vital part of the Big Bend’s tourist economy and our unique quality of life is Dr. Grady Blount, co-owner of the Big Bend Observatory near Terlingua, Texas. Ninety percent or more of his clientele travel to experience high quality night skies and astronomy-related phenomena, such as the recent comet Neowise or a first-hand view of the billions of stars in the Milky Way. Another example are astrophotographers Page Graham and his wife of 40 years, Carol, who wanted to find another hobby they could enjoy together, and who fell in love…with stars and nebulas. Now they travel to the Big Bend regularly to sit under the stars, take pictures, talk, relax and enjoy each other’s company.

Lee McMullen specifically relocated to the Big Bend to develop as a photographer. His night sky images take hours of traveling across the roughest roads, often working the darkest reaches of the country to produce. But some nighttime phenomena are a disappointment. Recently, Lee is finding what he terms “double sunsets” appearing in his night sky photos. He says they appear not because of natural light events, but from increased lighting that emanates from towns and cities miles away from where he might be working.  Light particles travel farther and faster than other phenomena, such as noise, and can have an immense, unintended reach and impact.  According to Lee, “It takes very little light to mess things up in a nighttime photo.” 

The most effective way to improve night sky quality over such a large region is through increased individual awareness and improved practices. Leading the way for this is Texas Local Government Code Title 7, Chapter 229 (2011) which directs municipalities “located in a county any part of which is located within 57 miles of a major astronomical observatory” such as the McDonald Observatory atop Mount Locke in Fort Davis to adopt night-sky friendly ordinances. Seven Texas counties have and are now updating their codes. But while statutory protections exist, and awareness is improving, night sky advocates living within the scope of the statute believe more could be done to improve understanding and reduce trespass light.

Less Artificial Light Exposure Means Better Sleep and Better Health

The creation of the Big Bend Dark Sky Reserve is good news for the scientific, economic and recreational sustainability of our region, but to focus solely on these attributes overlooks the important health and well-being benefits of high-quality night skies.

Humans and wildlife depend on Earth’s natural light and dark cycles, which govern biological processes and life-sustaining behaviors. Exposure to artificial light after sunset is an entirely unnatural occurrence which confuses biological regulation. Moreover, the invention of Light Emitting Diodes (LEDs) decouples artificial lighting from cost as a factor. An unintended consequence of increased LED use has been Earth’s vanishing night sky. Images of the United States captured by NASA and others depict dramatic changes. From space, Earth might appear to be a beautiful, brightly illuminated object. But imagine trying to sleep where there is no natural night, ever. Much less trying to see a single star from a place where the skies are overly lit.  

The scientific evidence indicates our nearly ubiquitous exposure to artificial light at inappropriate times has negative health consequences. Medical, biological, and social scientists continue to discover how artificial light activates our central nervous system, thereby disrupting biological circadian rhythms. Circadian rhythms are naturally recurring physical, mental and behavioral changes which occur on a twenty-four-hour cycle even in the absence of light. They are essential to various biological and cellular processes. Light in the blue and bright white range, such as those from many (but not all) LEDs, monitors, displays and cell phone screens is especially problematic.

Disrupted circadian rhythms caused by nighttime artificial light exposure affects aspects of physiology with direct links to cell cycle regulation, DNA damage response, and metabolism. Health impacts of light pollution may include insomnia, obesity, depression, sleep disorders, diabetes, chronic illnesses and even certain types of cancers, including breast cancer.

These findings are so serious, the American Medical Association House of Delegates issued a 2012 policy statement on nighttime lighting and human health published in the American Journal of Preventative Medicine. The AMA policy statement on exposure to artificial light after dark advocates for a reduction in unnecessary lighting and technologic solutions to ensure that when we use lighting, it optimizes visual performance while minimizing circadian disruption.

Unfortunately, the problem of artificial light pollution is extensive and expanding, even though it is easily mitigated. A 2016 atlas of the night sky published by astronomy researcher Fabio Falchi with the Light Pollution Science and Technology Institute in Thiene, Italy depicts a planet where more than 80% of the land area is so light polluted from artificial light that the Milky Way is invisible. According to Falchi, 99% of the combined U.S. and European population suffer the effects of light pollution. Another study estimates light pollution expanding globally at a rate of approximately 2.2% per year (Kyba, et al., 2017).

Light Pollution Reduction: Easy. Inexpensive. Immediately Gratifying.

Projects such as the proposed Big Bend Dark Sky Reserve will be an important part of the light pollution solution because they demonstrate how to protect and recover night sky quality. Light pollution can be easily, affordably and immediately reversed, “with the flick of a switch,” as it were, and much more quickly than air, water, or land pollution.With increased awareness and a few basic changes, such as only illuminating areas when in use, shielding bulbs and filaments and choosing warmer light tones, we all can help protect and restore night sky quality.

But what about safety and security?

Night sky friendly lighting practices do not sacrifice illumination and security. A 2015 study published in the Journal of Epidemiology and Community Health found no reductions in accident or crime rates attributable to increased street lighting. At best, the connection between light at night and crime reduction is weak. So, more light isn’t necessarily better. At worst, overly illuminating certain areas may have unintended effects, such as making property more easily visible to criminals: if you can see it, so can they. Improper light at night can also create night blindness, outward glare, or render the area beyond the lit area boundary less visible.

High traffic public areas where people unfamiliar with the terrain might be walking or driving require illumination that is safe and well-directed. The Hotel Limpia in Fort Davis reduced glare and improved visibility by installing downlighting and amber bulbs, with great results as seen below.

It may seem counter-intuitive, but in some cases not illuminating an area might be safer than leaving lights on. Using timers and motion detectors are considered more effective than leaving lights on full time. Shielding illumination sources reduces glare and improves visibility, directing light to where it is most useful. Ultimately, the goal is to strike a healthy balance between illumination, location and duration appropriate to the demands of the individual circumstance.

Where to Start?

A nighttime lighting assessment can be illuminating! The International Dark Sky Association recommends the following: light only what you need and only use artificial light when and where needed. Turn off lights when not in active use, use timers and motion-activated lights instead of leaving lights on full time to deter criminal or nuisance animal activity. This saves energy cost, protects night skies, and results in a more effective use of light.

 Technology and practices such as downlighting and shielding cut glare, improve illumination quality and spare the night sky view. This prevents artificial light from shining upward or outward and being wasted into the sky. Choosing bulbs and lighting sources that have warmer colors, such as warm white or amber bulbs, helps. LEDs come in an array of colors and some are programmable, ranging from cold, hard blues and bright whites (less desirable, less healthy) to warm white or amber tones (more desirable and healthier). Also, since indoor lighting can escape outdoors, take measures to prevent spillage. A good guide to remember is:  If you can’t see the bulb, glare can’t escape into eyes or the skies.

How Healthy are your Night Skies?

Experiencing natural darkness means different things to different people. For some, the night and natural darkness inspires fearfulness and dread. For others, it brings a sense of calm, connection with nature or a feeling of expansive freedom. Or a better night’s sleep. Natural darkness offers the joy and wonder of seeing the countless stars in the Milky Way emerge from the sky as day blends into night. And without quality nighttime skies, experiencing that once-in-a-lifetime astronomical event, such as a comet or meteor shower, would be impossible. Night sky quality is both a personal and a community-level experience. It is the direct result of our own awareness and practices. So, how important are quality night skies to you?

To advance night sky quality awareness and reduce light pollution globally, the International Dark Sky association has created several different designations that celebrate and protect natural night sky quality. These range from International Dark Sky Parks, typically located in wilderness and back country areas such as the Big Bend National Park and neighboring Big Bend Ranch State Park, to Urban Night Sky Places where planning design and practices not only protect but recover night sky quality. Even highly populated urban areas such as Flagstaff, Arizona, have dramatically reduced their artificial light pollution, regaining night sky quality, and improving nighttime conditions beyond city limits. 

In the Big Bend, different groups are approaching night sky quality from a variety of angles. The Big Bend Conservation Alliance names dark sky conservation in the scope of their mission. The McDonald Observatory, long known for its activities to protect night skies for astronomical viewing, has a growing list of demonstrations where night sky quality has been improved through the adoption of night sky friendly technology and practices. There is a new group forming to specifically focus on night sky conservation as the sole scope of their mission: West Texas Friends of the Night Sky. Each of these entities encourages individuals, neighborhoods and communities to protect and improve their night sky quality through awareness, education, and night sky friendly technology and practices.

These are encouraging developments, but as of this writing International Dark Sky Reserves are so rare that only 16 exist world-wide, and only one is located the U.S., in Central Idaho. If successful, the proposed Big Bend International Dark Sky Reserve will become Earth’s newest such place, enhancing quality of life, safety, and health benefits for all.

– By Leslie Hopper

Further Reading

Blair, Ada. (2017). An Exploration of the Role that the Night Sky Plays in the Lives of the Dark Sky Island Community of Sark. Journal of Skyscape Archaeology. 3. 236-252. 10.1558/jsa.34689.

Foster J.J., Smolka J., Nilsson, D-E, Dacke, M. 2018 How animals follow the stars. Proc. R. Soc. B 285: 20172322.

Hölker, F., Wolter, C, Perkin, E. K., Tockner, K. (2010). Light pollution as a biodiversity threat. Trends Ecol. Evol. 25, 681–682 (2010).

Hölker, F, Wurzbacher, C., Weißenborn, C., Monaghan, M. T., Holzhauer, S.I.J., Premke, K. (2015) Microbial diversity and community respiration in freshwater sediments influenced by artificial light at night. Philos. Trans. Roy. Soc. B Biol. Sci. 370, 20140130 (2015).

Keshet-Sitton, A. ,K. Or-Chen, K, Huber, E., Haim, A (2016). Illuminating a risk for breast cancer: A preliminary ecological study on the association between streetlight and breast cancer. Integr. Cancer Ther. 1534735416678983

Kyba, C. C. M., Kuester, T., Sánchez de Miguel, A., Baugh, K., Jechow, A, Hölker, F., Bennie, J. Elvidge, C.D., Gaston, K.J., Guanter, L. (2017) Artificially lit surface of Earth at night increasing in radiance and extent, Science Advances, American Association for the Advancement of Sciences. e1701528 (2017).

Lunn, Ruth M., Blask, D., Coogan, A.N., Figueiro, M.G., Gorman, M. R., Hall, J.E., Hansen, J., Nelson, R.J., Panda, S., Smolensky, M.H., Stevens, R.G., Turek, F.W., Vermeulen, R., Carreón, T, Caruso, C.C. (2017). Health consequences of electric lighting practices in the modern world: A report on the National Toxicology Program’s workshop on shift work at night, artificial light at night, and circadian disruption, Science of the Total Environment, Elsevier

Touitou Y, Reinberg A, Touitou D. (2017). Association between light at night, melatonin secretion, sleep deprivation, and the internal clock: Health impacts and mechanisms of circadian disruption. Life Sci. 2017;173:94-106. doi:10.1016/j.lfs.2017.02.008

Touitou, Yvan (1997) Yvan Touitou Light at Night: Pollution of the Internal Clock, a Public Health Issue. (Touitou Y. Light at night pollution of the internal clock, a public health issue. Bulletin of the Academy of National Medicine, 2015;199(7):1081-1098)

Steinbach R, Perkins C, Tompson L, et al. (2015). The effect of reduced street lighting on road casualties and crime in England and Wales: controlled interrupted time series analysis. J Epidemiol Community Health 2015; 69:1118-1124.

 Stevens, Richard G., Brainard, G.C, Blask, D.E, Lockley, S.W, Motta, M.E. (2013) Adverse health effects of nighttime lighting, American Journal of Preventive Medicine, Elsevier (2013;45(3)