by Bob Bohley, NPS Master Astronomy Volunteer at Great Sand Dunes NP&P

Great Sand Dunes National Park and Preserve was certified as an International Dark Sky Park in April of this year by the International Dark Sky Association (IDA) of Tucson, AZ. This was the culmination of four years of concerted work and nine months spent on the application process. Great Sand Dunes has long been known for its incredible night sky views, and this certification will ensure that these dark skies will be preserved for generations to come. It joins approximately two dozen other units of the National Park Service to be so named. There are three basic requirements to become a Dark Sky Park:

  • Reduce your own artificial light impact
  • Measure the darkness of your night skies
  • Communicate the importance of dark skies to the public and work with neighboring communities to improve lighting

Why are dark skies important to the people of Colorado in particular and to the people of the world in general? Timothy Ferris, the author of popular books on astronomy, says that “all human cultures no matter how primitive have felt it important to tell stories about the stars and about the nature and the origin of the Universe as a whole. So there’s something about astronomy that is deeply ingrained in human culture going as far back as music, dance and poetry.” But we are losing this important human connection to our dark skies.

According to Barbara King- solver, a science writer, novelist and poet, “in the summer of 1996, a subtle, unheralded transition took place—the majority of the Earth’s population was now urban rather than rural. Consequently, the environment most of us live in now is one of concrete, steel, brick, glass and artificial light. Our celestial views are vanishing. I wonder how people will imagine the infinite when they have never seen how the stars fill a dark night sky.” It is estimated that by 2050, two thirds of the world’s population will live in cities. NASA estimates that only 17% of Americans have ever seen the Milky Way—our home galaxy.

Our National Parks, particularly in the west, provide places of refuge from urban life where visi- tors can reconnect to their cultural and historical ties to celestial wonders above. Here at Great Sand Dunes National Park and Preserve, we greet roughly half a million visitors annually from all over the United States and the world and invite them to share our recuperative night skies.

Thomas Edison patented the first commercially viable incandescent light bulb in 1879, a mere 140 years ago. Sure, it’s thrilling to see a thousand stars in a dark night sky, but artificial light has been a tremendous boon to mankind. Un- fortunately, 140 years of artificial light isn’t even a blink of an eye in evolutionary time. All life, whether it be plant, insect, animal or human, evolved hundreds of thousands to millions of years before the light bulb changed our world. We’re all struggling to adapt to this new world of light. We have developed a Circadian Rhythm, our day-night cycle. We live in a world of light now, and our rhythms have been disrupted. Our human brains are hard-wired to ac- quire information during our waking hours and process that information while we sleep. What information should be kept and what can be dis- carded? Our brains are trying to link what we learned during the day to memories we already have.

So what can we do about this disruption to our Circadian Rhythm? First, manage your sleep cycle. The Center for Disease Con- trol says that adults should get at least seven to eight hours of sleep a night; teenagers should get nine hours of sleep; and it goes down to

toddlers needing ten to twelve hours of sleep in a 24-hour period including naps. Put down your devices or set them to go to a softer light two hours before you plan to retire for the night.

Outdoor lighting

The night sky is a completely recoverable natural resource with properly designed and installed out- door lighting. The IDA has six out- door lighting principles that have been adopted by the National Park Service.

• Light only if you need it
• Light only when you need it
• Aim the light where it is needed • Use appropriate color spectra 
lighting (<3000°K)
• Use the minimum amount of
light necessary
• Use energy-efficient lamps and fixtures

Great Sand Dunes has written these principles into our Lighting Management Plan. Over the past four years, our Facilities Manage- ment Team has been replacing outdoor lighting fixtures with fully shielded, downward facing, programmable, energy efficient (LED) fixtures. IDA requires that outdoor park lighting must be at least 67% IDA compliant at the time of application. We are 81% IDA compliant today and are committed to be 95% compliant in five years and 100% compliant within ten years.

The second requirement to be- come a Dark Sky Park is to measure the quality of our night skies with a special photometer that measures darkness. Our Resources Management Team has taken three years of data on our sky quality, and these measurements put us in the Gold Tier (darkest) park designation. The Sangre de Cristo Mountains effectively shield us from the light domes of the Front Range population centers making Great Sand Dunes one of the darkest places in the nation. Finally, we continue to communicate the importance of dark skies through our Ranger-led Moonlight Walks and our Evening Ranger Programs. We are also working with Alamosa and Saguache Counties on lighting issues that could impact the park.

Research has shown that camping two to three nights under the stars can completely reset a person’s Circadian Rhythm. Great Sand Dunes National Park and Pre- serve is one of the best places in the country to do just that. We invite you to join us and gaze in awe at the celestial wonders above. Remember “Half the Park is after Dark.”