Dark Sky Park Certification

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Dense clusters of stars shine brightly in a wide, dark sky above a shadowy, tree-lined horizon.

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A full moon rises over the silhouette of a dark, tree-lined island on the shores of a scenic lake at dusk.
A full moon rises over Sphunge Island on Kabetogama Lake. The park's many shorelines provide clear areas with wide, open views of the night sky.

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A Certified Dark Sky Park

Surrounded by miles of lakes and wilderness area, the skies above Voyageurs are free from the excessive, misdirected, and obtrusive artificial light often produced in large urban cities. The northern night skies in Voyageurs have historically been valued and observed by many people including the Anishinaabe, the bold and outgoing French-Canadian voyageurs, lumberjacks, gold miners, commercial fishermen, and present-day visitors. By becoming a Dark Sky Park, Voyageurs can better preserve the amazing cultural, historic, and natural resource that is our night sky.

The First Step: Learn Your Lights

To become Dark Sky certified, Voyageurs partnered with the National Park Service’s Natural Sounds and Night Skies Division as well as the International Dark-Sky Association (IDA): the globally-recognized leading authority on combating light pollution. IDA’s mission is to preserve and protect the nighttime environment and our heritage of dark skies through environmentally responsible outdoor lighting.

In 2019, the park worked with the IDA to take major steps towards certification. First, staff checked all man-made lights in the park to determine which ones create light pollution. Once the incompliant lights were identified, the park began to retrofit or replace them with "night sky friendly" lights—many of which were provided by the Voyageurs National Park Association.

Click, hold, and drag the button below to see the difference between night sky friendly lights and lights that contribute to the sky glow caused by light pollution.

 
Not all lights are made equal.
Tall lights at a parking lot  contribute to sky glow and spill light significantly into the wetlands beyond the parking area. Dark sky friendly light shine directly downwards towards a parking lot. A shield at the top directs the light downwards and prevents glow from spreading more than a couple feet into the grass beyond the parking lot.
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Many lights contribute to sky glow by directing light upwards or to the side. The lights in the left image at the Rainy Lake Visitor Center contribute to sky glow and spill light significantly beyond the parking area. They are slated to be replaced with night sky friendly lights.

Night sky friendly lamps only direct their lights downward, towards the people who use them. The night sky friendly lights in the right image were installed at the Kabetogama Lake Visitor Center in summer, 2019. A shield at the top directs the light downwards and abruptly prevents glow from spreading more than a few feet beyond the parking lot. 

In addition, some lights can also be considered night sky friendly lamps if they use red coloring (which does not disrupt night vision as much as yellow or white light), or if they shine only for a brief time when activated by a motion sensor.




 
An upside-down light bulb is surrounded on all sides except its top by a dark, metal cylinder.
A shielded night sky friendly light installed near the Rainy Lake Visitor Center

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Becoming a Dark Sky Park occurs in multiple phases. In Phase 1 the park’s goal was to increase the number of “dark-friendly” lights from 25 percent to 68 percent, with a long-term goal of obtaining 100 percent within the next 10 years (or preferably earlier).

Surrounding neighborhoods, businesses, and communities are not required to change their lights when Voyageurs to become Dark Sky certified. However, there are many visual and economic benefits to using night sky friendly lights, and the park welcomes all who want to support dark skies. To promote and inspire visitors on the use of effective outdoor lighting, the park expects to host multiple Dark Sky public programs and special events.

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The Second Step: Measure the Dark

How dark is “dark enough” to be a Dark Sky Park, and how does darkness get measured? Over the last 10 years, scientists from the National Park Service’s Natural Sounds and Night Skies Division have provided Voyageurs with special equipment for the park to monitor sky quality and light levels. In addition, the Voyageurs National Park Association has also been a major partner in providing financial support for dark sky monitoring equipment and the replacement of old lights with night sky friendly lighting.

 

The Bortle Scale

The Bortle Dark Sky Scale rates sky quality on a scale of 1 - 9. A rating of “Class 1” represents a pristine night sky, and “Class 9” represents a severely light-polluted sky in which only the very brightest dozen or so stars and planets may be viewed. Only a few areas in the lower 48 states display class 1 or 2 skies. The sky quality in many western national parks is class 3 or 4. Class 5 and higher skies are often found around large metropolitan areas.

 
A bright streak of green-colored stars crosses a blue and purple sky in the shape of a circle. Near the rim of the circle are dark silhouettes of trees and a green/yellow glow, representing sky glow on the horizon.
This sky quality image was taken with a CCD camera on the shores of Rainy Lake.

Image Credit: Lapp and Larson

Sky Quality Meter Lens (SQM-L)

The SQM-L is a hand-held device with a narrow-view lens for detecting light from the night sky. After taking a reading, the SQM-L reports a value in magnitudes/arcsecond. “Magnitude” refers to an object’s brightness (the object can be a star, a lamppost, etc.), and an arcsecond is a standard amount of space in which the light from an object is measured. Lower values represent a brighter sky, and higher values (up to 22.00) represent a section of dark sky free from the influence of light pollution.

Charge-Coupled Device Camera (CCD)

A wide-field CCD camera is a research-grade digital camera that captures the whole sky from one horizon to another through a series of circular images. The edges of these photos represents the site’s horizon, and the center represents the zenith (the area of night sky viewed directly overhead).


 
Two circular images are compared side by side. In the first image a streak of bright blue-colored stars stretches across the circular image of a dark blue night sky. The second image roughly mirrors the first, changed to colors of purple, red, and blue.
Two images created with a CCD device at the Ash River Forest Overlook in 2019

Image Credit: Lapp and Larson

The devise then measures the brightness of the images based on a logarithmic scale and superimposes “false colors” over the photos (yellow, red, and white correspond to a brighter sky; blue, purple, and black correspond to darker sky). Artificial sky glow is always brighter near the horizon than at the zenith. For this reason, the outer edges of CCD images tend to be brighter than the center. The brightness of an area’s horizon substantially affects the overall light level at a site.

Each completed measurement results in two figures. The first figure is a full resolution mosaic of the sky rendered in false color. The second figure is an image that compares the brightness of the site where the photo was taken against the brightness of an already-registered Dark Sky park or area. This provides an at-a-glance representation of the amount of light pollution from sky glow observed at the site.

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A cluster of bright stars--three in a straight line forming the "belt" of Orion--shine above a scenic, shadowy wooded area.
The constellation Orion. Several low-level magnitude stars can easily be seen in this winter constellation. Many other higher magnitude stars are more faint, but still visible.

Image Credit: A. Mike

Count the Stars: the “Visual Limiting Magnitude at the Zenith (ZLM)” Method

The ZLM method is one of the most common ways to measure sky brightness, and it can be a good option for amateur astronomers who do not have access to special equipment. Brighter objects are represented by lower magnitudes (e.g.. very bright stars may be magnitude 2 or lower, and dim stars can have a magnitude of 6 or higher). To use the ZLM method, look up and calculate the magnitude of the faintest stars you see using an apparent or absolute magnitude equation.

A sky is often considered “dark” if a person can see stars of magnitude 6.0–6.3. However, evidence has shown that stars 2–3 times fainter at magnitude 7.0–7.5 can be seen by skilled observers under the best of conditions. For this reason, the ZLM method has a larger margin of error in dark sites. However, it is still a popular tool for any visitor who is interested in measuring sky glow in the park, or even near their own home. The ZLM method is often easier to use in areas with greater amounts of sky glow, where bright stars are fewer in number and stand out more.

For anybody interested in measuring sky glow in Voyageurs using the ZLM method, it helps to practice stargazing techniques such as letting your eyes adjust and looking at faint stars out of the corner of your vision instead of straight on. Learn more by visiting our stargazing page.

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A bright band of stars stretches upward from the shadowy silhouettes of trees on a distant horizon.

NPS / Lapp

Exploring the Dark

There are countless ways to explore and enjoy Voyageurs at night, both during and after the park becomes Dark Sky certified.

1. Go Stargazing

Spend the evening searching for wonders of the night: distant planets, the luminance of the full moon, the International Space Station zooming overhead, streaking meteorites as they burn in the atmosphere, the river of stars that spans across the Milky Way, and the breathtaking Northern Lights.

2. Listen to the Voices of the Night

Many species in the park are night-active, timing their activities to benefit from the darkness. A remarkable 30% of vertebrates and 60% of invertebrates are night-active. Listen for the chirp of frogs, the wail of loons, the low hooting of owls, and even the howling of wolves in the distance.

3. Learn the Stories of Stars

For thousands of years, civilizations around the world have observed seasonal patterns of stars appearing and disappearing across the horizon. Learn stories of the constellations that inspired people to navigate, explore, predict seasonal changes, and to portray lessons regarding their culture, religion, and ways of life.


 
A bright full moon illuminates the shadowy silhouette of a pine tree and reflects in the dark waters of a scenic lake.

Image Credit: NPS / M. Challeen

4. Test Your Night Vision on the Trail

Try going on a night hike. If you are nervous about being outside at night, bring a friend and/or a red light. You might be pleasantly surprised how well the human eye can see after dark. Several studies have shown that even in large cities, low-level lights are more effective and efficient for navigating streets (and even deterring crime) than bright, unshielded lights.

5. Go Camping and Sleep Under the Stars

Exposure to artificial lights (particularly the white wavelengths of sky glow) during regular hours of darkness can disrupt our bodies’ circadian rhythm, which is responsible in part for the regulation of sleep. Studies have alluded to the benefits of sleeping in natural darkness, including a lower risk of breast cancer, weight gain, and metabolic disorders such as diabetes.

6. Practice Exploring Dark Skies at Home

We all benefit from darkness, and dark skies are not only for parks; businesses, residences, and communities can become dark sky friendly locations, too. Even simply switching your light bulbs can conserve energy, reduce light pollution, save money, and make your home more environmentally friendly.

 
A full moon rises over the silhouette of a dark, tree-lined island on the shores of a scenic lake at dusk.
Earlier nights, fewer insect pests, and fewer people make wonderful opportunities to enjoy the night sky during the cooler seasons.

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LED lights produce virtually no heat compared to traditional incandescent light bulbs, which waste up to 80% of their electric energy in heat generation alone. A 6.5 Watt LED light saves 60-70% of the energy needed (and 90% of the economic expense) to produce the same amount of light as a 100 Watt incandescent light bulb.

7. Explore the Night in Autumn, Spring, and Winter

Watch the stars from an ice road, go night skiing or snowshoeing, or simply start a campfire on the shore with your friends and family. Winter also offers an opportunity to view constellations that cannot be seen during summer nights.

8. Join Other Dark Sky Enthusiasts

Join an astronomy club, attend a night sky program in the park, or get involved with a group supporting Voyageurs’ Dark Sky certification like the Voyageurs National Park Association. If you don’t want to join a group, simply coming up to visit and view the stars can create some amazing memories for you, and it also makes a positive impact on the park and local communities.


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Last updated: March 21, 2021

Contact the Park

Mailing Address:

Voyageurs National Park Headquarters
360 Hwy 11 East

International Falls, MN 56649

Phone:

(218)-283-6600

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