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Dark Canyon, Dark Sky

I wanted to create a print to commemorate my family’s visits to the Black Canyon of the Gunnison and all I learned upon visiting the National Park and let other folks know about this special place.

Between surges of the Covid pandemic, I flew home to Denver, Colorado in July 2021 to visit my 92-year-old mom and take her on a road trip to see Black Canyon of the Gunnison, near Montrose, Colorado, the least visited National Park in CO.  We arrived in the park early in the morning  when it opened, and the Visitor Center parking lot was full by 10:30 a.m. on a Tuesday! Mom had visited the Park with her dad in the 1950’s when she was in her 20’s after college, on her way from Texas to Colorado to be a ski bum.  Black Canyon of the Gunnison was first established as a national monument in 1933, and later was redesignated as a national park in 1999, as often happens with monuments.

The Canyon borders Curecanti National Recreation Area and Gunnison Gorge National Conservation Area.  Carved in Precambrian, 1.7-billion-year-old rock, the canyon is 40 feet in width at its narrowest and the “Painted Wall” feature is 2,250 feet in depth- the tallest cliff in North America.  Pale streaks of pegmatite dikes zigzag through the Precambrian gneiss and schist dark wall which originally formed during an intense volcanic period.

Some parts of the canyon only receive 33 minutes of sunlight a day.  In comparison, the larger Grand Canyon is 1 mile deep and up to 18 miles wide with layered bands of red and orangish colored rock, but some think the Black Canyon is more impressive because the drive up viewpoints allow you to get closer to the vertical cliffs and Gunnison river below, the largest tributary of the Colorado River. When I texted my brother about our visit, I learned he had kayaked in the Canyon and had encountered dangerous strainers in the river which required portages through poison ivy.

Black Canyon of the Gunnison National Park was certified as an international dark sky preserve in 2015 for being free of light pollution.  Not only is the park good for night star gazing for humans, but nocturnal animals such as owls and rodents have developed keen hearing, smell, and dark-adapted vision to navigate at night. Some species come out at night to escape the heat of the day and others need the night to hunt, mate, or avoid predators. A host of animals and plants’ circadian rhythms rely on an unaltered night sky. According to the park website, to preserve dark skies in the park, only artificial lighting necessary for safety is used and motion detectors limit the light and all outdoor lighting devices use low-energy, low-impact bulbs with shields that direct light to the ground where it is needed.  Not only does the park promote responsible lighting, but it runs astronomy educational programs. 

The darkness of the sky is measured by sky quality meters (SQMs) which read sky brightness in magnitude per square arcsecond. The higher the number, the darker the sky. The highest possible rating is 23.  As of 2019, parks must have an average reading of 21.2 or higher to be eligible for consideration as an International Dark Sky Association Park.  Black Canyon of the Gunnison readings have historically averaged 21.5. Big cities such as Denver, Colorado have readings around 18.

The park allows access for sky viewing at night, using a personal telescope, or for astrophotography. Red light-equipped headlamps or flashlights are best to help preserve night vision and reduce light pollution. The best time to view the stars and Milky Way galaxy is when the moon isn’t out-during the new moon phase, or at times when the moon rises late in the night. Check the moon phase, moonrise, sunrise, and sunset times for Black Canyon.

The Milky Way shines brighter in the summer than the winter. This is because we face the center of our galaxy on summer nights. As we look to the center, we look at the combined light of more stars. In the summer, the Milky Way rises higher and higher throughout the night, resting directly overhead late in the evening. During the fall, the Milky Way appears directly overhead very early in the evening.

Resources:

  1. Black Canyon of the Gunnison National Park & Curecanti National Recreation Area Geologic Resource Evaluation Report, Natural Resource Report NPS/NRPC/GRD/NRR—2005/001, Black Canyon of the Gunnison National Park and Curecanti National Recreation Area Geologic Resource Evaluation Report (nps.gov).
  2. Measuring Lightscapes – Night Skies (U.S. National Park Service) (nps.gov)
  3. Preserving The Dark, Astronomy – Black Canyon Of The Gunnison National Park (U.S. National Park Service) (nps.gov)
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