The Environmental Journal of Southern Appalachia

Wednesday, 23 March 2022 11:52

It’s Sirius: Light pollution blots out the night sky but pockets of true darkness remain

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Southeast at nightThe Southeast is seen at night from the International Space Station. NASA

Dark Sky parks, including some in East Tennessee, offer true views of heaven

“Look up at the sky. There is a light, a beauty up there, that no shadow can touch.”  J. R. R. Tolkien  

WARTBURG — Those who came before us read the night sky like we read maps today.  

In ancient times, pointing to the stars, they imagined creatures, mythological heroes and common every-day objects. Because of their fixed positions, the constellations became a foolproof way to navigate across vast, featureless deserts and expansive seas. The stars marked the changing seasons and the passage of time. The star patterns were memorized and taught to each new generation.

These are the same constellations we recognize today. Some cultures, and modern-day adventurers, still navigate by starlight.

The ancients also looked to the dark night sky for spiritual guidance and to divine the future. Comets, mysterious auroras and streaking meteors intrigued their psyche. Maji followed a bright star to find the Christ child.

They made rudimentary clocks and calendars based on the moving stars, not realizing it was actually them moving beneath the stars, the Earth spinning as it orbits the Sun.

Towns and waypoints were aligned to follow the stars coursing through the heavens. Even buildings and edifices featured a form of celestial architecture. To them, the dark night sky represented order.

This unfettered access to the night sky began to change with the invention of artificial light. While initially bringing great benefits and enhanced productivity, and providing security at night, it morphed into an all-consuming vanquisher of what was a constant companion to our Earthly existence, the starry night sky. Now two-thirds of Earth’s human population can’t see the Milky Way on a clear night.

Light pollution can be hard to pinpoint, as it seems to emanate from everywhere. Because there are no single point sources, its effects are pervasive and subtle in ways other pollution isn’t. But in the end, it is still pollution, like any other.

Seeing the Milky Way, and other features of outer space, requires a very dark night sky. Because light travels until absorbed or redirected, whether by reflection or refraction, it will permeate entire atmospheres if not contained.

Once a given, human-created light now obscures a timeless and boundless natural resource.

Fortunately, regaining dark night skies is pretty straightforward. If we do, then maybe those of us living in cities, and most of us living east of the Mississippi River, could then maybe see what a starry sky really looks like, not the few lonely stars we’re used to seeing.  

In the remotest parts of Southern Appalachia, there are places where truly dark skies still exist, the precious few that artificial light hasn’t found, yet.

Standing still on a clear night, away from artificial light, and looking skyward, you can see the celestial bodies moving east to west, 54 constellations at a time in the Northern Hemisphere.

Because stars, which are simply another name for suns, are many light years distant from Earth, it takes time for their light to arrive. Viewed from Earth, stars appear to be on the same plane and equidistant from Earth, but are actually light-years apart. A light year is the distance light travels in one year, at 186,000 miles per second. 

We see the stars concurrently across different time spans, depending on a star’s distance from Earth. This determines how far back in time a star appears. We see them as they were in the past.

Likewise, light traveling away from Earth would take the same amount of time, so that 40 billion years from now it would appear at a point 40 billion light years away from Earth.

Earth’s atmosphere creates the illusion of blinking stars as their light passes through it. Stars don’t twinkle when viewed absent Earth’s atmosphere.

In our galactic neighborhood there are 1,700 suns with orbiting planets with a direct view of Earth.

What better way to understand all this than to go outside on a clear night, away from the city, and see the stars for yourself.

Why dark skies

Most people east of the Mississippi River must drive half a day just to see the Milky Way and encounter a truly dark night sky. Millions never have, and think nothing of it.

“The visitor from Washington, D.C., it’s common to see their jaw drop,” Sky Meadows State Park (Virginia) Manager Kevin Bowman said. “Once they experience what a truly dark sky looks like.”   

Visitors can see all the stars that can be seen from Earth because of the work done by the park to become certified as an International Dark Sky Park.

Bowman said one first-time visitor to the park remarked what a perfectly clear night it was, if it wasn’t for that one cloud. A person standing next to him said “that’s not a cloud, that’s the Milky Way.”

In Tennessee, similar reactions are found at Obed Wild and Scenic River, also an International Dark Sky Park. 

Pickett CCC Memorial State Park, and adjoining Pogue Creek Canyon State Natural Area in East Tennessee are also certified International Dark Sky Parks.

“I’ve had people look skeptically into the end of a telescope to see if there’s a photo when viewing Jupiter’s moons or Saturn’s bands of colored rings,” Obed Interpretive Park Ranger Rick Ryan said. “One time, a visitor thought the star Sirius might be an UFO, it was so bright.”

“Dark sky is a natural resource that is disappearing over time,” Ryan said. “We consider our dark sky as important a natural resource to protect as any other in the park, like the wildlife or the river itself.”

For this reason, the Obed has become a destination for traveling stargazers. “People come from several states away, and plan trips to the Obed just to experience a Dark Sky Park,” Ryan said.

We are so scared of the dark, we have over-lighted our cities and suburbs, creating a type of pollution seen only at night, if recognized at all. In many places, competitors wage light wars, an outdoor-lighting arms race, culminating in a Times Square or Las Vegas Strip.

Night vision improves as darkness advances. Once eyes adjust to darkness, the least bit of artificial light can compromise the ability to see in the dark.

Rods and cones in the eye connect to the brain, telling it whether it’s night or day, and whether to sleep or rise. Disrupting this circadian rhythm is why employers pay more for third-shift work. Over time, this disruption takes its toll on people’s health. Humans aren’t made to work at night and sleep during daylight hours. A lack of naturally occurring darkness has been linked to obesity, diabetes and some common mental disorders.

Even low levels of artificial light can alter wildlife behavior. In some animals, light regulates hormone levels.  Migrating birds sometime fly toward city lights on the horizon, mistaking them for a rising moon. Even bats are sensitive to light pollution. They prefer darkness, but are not completely blind. Along with echolocation, what little vision they do have helps locate insects at night.

Many animals are nocturnal, active mostly at night, and are especially sensitive to unnatural, man-made light.  

Dark places also tend to be quieter. These places feel remote when removed from the din of modern culture. If wilderness is defined as untrammeled by man, then include the absence of light and noise pollution.

Unnatural light also stresses local flora, which has its own light-cycle rhythm, so light pollution pretty much affects every living thing.   

Reducing light pollution also leads to reduced energy consumption. In Southern Appalachia, this is especially helpful as long as fossil-fueled power plants dot the landscape.

Restoring dark skies

The Obed was Dark Sky certified in 2017  by the International Dark Sky Association (IDA). It also has the distinction of being one of the few free-flowing federally protected rivers in the United States.  

“Restoring dark sky is more important in the East,” Ryan said. “We take it very seriously. We have no outdoor lights whatsoever, and the park never will have outdoor lighting, because it’s written into the park plan.”  

Restored dark sky can showcase light pollution to educate the general public, leading to more restoration, and so on.

Outside of a park, it will be up to the citizenry to protect a park’s dark sky from outlying communities, especially gateway communities, whether voluntarily or by ordinance, or a combination of both.

One key element, Ryan said, will be converting to shielded, downward-facing lights in warm hues rather than white or blue. “Blue lights are the worst,” Ryan said.       

In Virginia, Bowman’s light-management plan incorporates timers to keep lights off at night. Named after Scotland’s Skye Farm, Sky Meadows is 15 minutes away from the nearest town. Bowman hopes the surrounding community will get involved, once they visit the park.  “We promote education by demonstration,” Bowman said. “The park itself is not really the point. It is dependent upon the nearby communities and their outdoor lighting choices.”

But a government agency generally doesn’t lobby another, especially out of jurisdiction. This avoids any conflicts of interest.

Darkening the night sky by asking people to give up outdoor lighting, and embrace the dark, is no simple matter. Making small, incremental changes allows people to see the intent of restoring darkness to the night isn’t to make the ground dark, just the night sky.

Downward-facing indirect lighting in warmer hues protects the local biotic. As pedestrians enter an area, they will see a pleasingly lit path protecting the night sky. Judicious use of both reflective and non-reflective surfaces provides light where needed while reducing the overall ambient light, dramatically improving the night sky view.

Eventually, local ordinances will become necessary to further reduce the photon footprint.

Communities can gradually pass stricter ordinances while, at the same time, grandfather in exceptions. Using the Bortle Scale, landscape architects can measure light pollution levels to track their progress restoring dark skies, eventually restoring integrity to the night sky.

A common approach to regulating light sources are value-driven ordinances, starting with the presumption of no artificial light whatsoever, then incrementally introducing light sources as needed. Eventually, a point is reached where light pollution overrides the need for the artificial light itself. That’s where the line is drawn to leave more dark night sky for more people to enjoy.  

Communities already benefiting from ecotourism can now attract a new kind of ecotourist. Dark Sky Parks are destination parks for those seeking ecological balance when planning a trip. A Dark Sky park rounds out this reconnection to the natural world.  

An example of using light to enhance, not diminish, the visitor experience is what’s been done at Grand Canyon National Park. Warm-hued, downward-facing light protects the starry skies. Of course, the dry desert air doesn’t hurt either.    

Regular, consistent measurement of light pollution levels and annual audits are mandatory to maintain Dark Sky certification, typically a three-year process requiring extensive documentation.

A true wilderness experience is to sleep under starry skies, embracing the dark. For most people east of the Mississippi River, the easiest way to ensure a dark night sky is to visit a Dark Sky park, where “half the park is after dark.”

But before you go, please turn off the lights.

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