Star Light, Star Bright, Where Are All the Stars Tonight?

A hundred years ago, you could look up at night and see a starry sky, the Milky Way, shooting stars or even the northern lights. Today, these spectacular cosmoses are disappearing from view, made invisible by light pollution (the excessive use of artificial light).

Over 80% of the world’s population lives under a light-polluted night sky. Light pollution is not limited to cities and other urbanized areas. Surprisingly, 99% of the U.S. public does not experience a natural night, and the National Park Service (NPS) has documented skyglow—the brightening of the sky over inhabited areas—from cities over 200 miles away in various national parks.

Why It Matters

The increased use of artificial light not only impairs our view of and ability to study the universe, but it also impacts human health, disrupts wildlife, provides a false sense of security and wastes energy and resources. Research suggests that the presence of light at night can interfere with our natural circadian rhythms (i.e., biological clock) which may lead to certain health problems.

Artificial light can also affect ecosystems by disrupting nocturnal activity, interfering with reproduction and reducing certain wildlife populations. Birds that use moonlight or starlight to hunt or migrate, for example, may become disoriented and veer off course. Artificial light may cause premature or late migration, which can result in missing ideal climate conditions conducive for nesting or foraging.

From a safety standpoint, people feel that brighter lights mean improved security. However, excessively bright or poorly-aimed lighting can make property and victims easier to identify and decrease safety by creating shadows that hide intruders. Furthermore, outdoor lighting that emits too much light or is used when it’s not needed depletes energy and resources.

As urbanization continues to grow and the use of excessive and inefficient light increases, so does the need to understand the impacts of light pollution and the role dark skies play in protecting our environment.

The Dark Sky Movement and Dark Sky Initiatives

The dark sky movement—a campaign focused on the effort to reduce light pollution—began when astronomers noticed skyglow obstructing views of the night skies. They began moving farther and farther away from cities in search of pristine night skies to observe and study the planets and stars. However, it soon became clear that simply distancing themselves from growing cities would not stop the inevitable disappearance of dark skies.

Several associations now operate both nationally and globally to bring awareness and educate the public on the hazards of uncontrolled artificial light. For example, the U.S.-based International Dark-Sky Association (IDA), formed in 1988, is a non-profit organization that focuses on raising awareness about the value of dark skies and certifies parks and other locations that have reduced light emissions.

The IDA established its International Dark Sky Places Program in 2001 to encourage communities, parks and protected areas around the world to preserve and protect dark sites through responsible lighting policy and public education.

Dark Sky Legislation

Flagstaff, Arizona, home to the Lowell Observatory, was the first community to enact a light pollution control ordinance in 1958 by banning the use of commercial searchlights within the city limits. Since then, more people are taking regulatory action to bring back the night sky.

At least 19 states, including Arizona, Colorado and Wyoming, have enacted laws to reduce light pollution. Some municipalities have also started adopting light pollution regulations as part of zoning codes.

The most common dark sky legislation requires the use of energy-efficient, shielded light fixtures in outdoor environments. Shielded light keeps light focused downward on the objects and areas that need illumination. Other laws regulate the times certain lighting can be used. For instance, lighting curfews require lights to be turned off after businesses close or when traffic is minimal.

In recent years, as more people have become aware of light pollution and its potential adverse effects, it has been identified as an environmental resource in the National Environmental Protection Act (NEPA) permitting process.

NEPA ensures a thorough environmental analysis is performed at the beginning of the planning process for a proposed project. This allows for recommendations to protect, restore or enhance the night sky resource. This has been the case for many projects near national parks and other designated Dark Sky Places.

Although a project may not be located within a national park boundary, its proximity may cause a lighting concern. For example, standing more than 200 feet tall, wind turbines require obstruction marking lights (several hundred flashing lights) to meet Federal Aviation Association guidelines as well as the associated security lighting at substations and operation and maintenance facilities.

On recent wind farm projects located near a national park, the NPS required a night sky analysis to evaluate the impact of nighttime lighting from observation points within the park. To help reduce potential impacts from tower lighting, project proponents are proposing to implement Aircraft Detection Lighting Systems (ADLS). The ADLS controls the aviation obstruction lights, turning them off and on when an aircraft is detected in proximity to the wind facility.

The Bureau of Land Management also required a night sky analysis for a mining project located near the Boundary Waters Canoe Area Wilderness, a designated Dark Sky Reserve in Minnesota. In this instance, the concern was for lighting associated with aboveground facilities for the maintenance and operations buildings, substations and storage areas.

Keeping Dark Skies Dark

The good news is that light pollution is easily reversible. Although it is not feasible to turn off all nighttime lights, steps can be taken to reduce light pollution and better protect our environment.

The NPS provides the following recommendations for evaluating outdoor lighting:

• Light only where you need it: Choose locations wisely. Unnecessary lighting can waste energy and money.
• Light only when you need it: Use motion sensors or timers to turn lights on and off as needed.
• Shield lights and direct them downward: Shielded fixtures prevent light from shining above the horizon.
• Select lamps with warmer colors: Amber-colored lights emit longer wavelengths, protecting the eyes and minimizing light pollution.
• Use less light: An efficient, shielded light fixture is effective while using a lower-wattage bulb.
• Select energy-efficient lamps and fixtures: Replacing poor outdoor lights with modern, efficient fixtures is not only good for the environment but also improves security and saves energy and money.

Dark Skies are an environmental resource that people often overlook. As human development expands further into the natural world, so, too, does the importance of minimizing our encroachment on the affected habitats. Reducing our impact on the night sky, both its beauty and ecological significance, allows us to protect this understated but essential aspect of the environment.

Article originally published in the Winter 2022 issue of Currents. Subscribe today to stay current on environmental insights and regulatory updates that impact your projects.