The night sky is getting brighter. Not because the stars are burning hotter, but because the lights humans have installed below are growing more numerous and more powerful every year. Since 2011, the artificial glow of the night sky has increased at roughly 10 percent per year, a compounding rate that, if left unchecked, will eventually render true darkness a memory for most people on earth. In New Hampshire, the cost of that trend is playing out differently depending on where you are, and the state’s least-developed corners are sitting on something increasingly rare and valuable.

A recent episode of NHPR’s Outside/In titled “In Defense of Darkness” builds the case for treating light pollution as a serious environmental issue rather than an aesthetic preference. The program features Megan Eaves-Egenes, who grew up under the dark skies of rural New Mexico, developed a deep connection to astronomy, and has since worked to document what happens when artificial light replaces the natural cycle of day and night. Her argument is not nostalgic. It is ecological, medical, and economic.

What Light Pollution Actually Does

The environmental impacts of light pollution are more severe and more varied than most people recognize. The most visible symptom is the loss of the night sky itself, the inability to see stars, planets, and the Milky Way from populated areas. But the consequences extend well beyond the loss of stargazing opportunities.

Birds that navigate by the stars are disoriented by artificial light and collide with illuminated buildings in enormous numbers, particularly during migration season. Sea turtle hatchlings on coastal beaches move toward light rather than toward the ocean’s reflection of the moon, leading them inland and to their deaths. Crickets and other nocturnal insects lose the ability to tell day from night, disrupting mating cycles and food webs that depend on their activity. Fireflies, which use bioluminescence to find mates, are being crowded out of their habitat as suburban light overwhelms their signals.

For humans, the consequences are increasingly well documented. The human body’s circadian rhythm depends on the cycling of light and darkness to regulate sleep, hormone production, metabolism, and immune function. Artificial light at night, particularly the blue-spectrum light emitted by LED streetlights and screens, suppresses melatonin production and disrupts the hormonal cascade that depends on it. The public health literature connecting light pollution to higher rates of certain cancers, sleep disorders, obesity, and cardiovascular disease is still developing, but the direction of the evidence is consistent.

Beyond the biological, there is the economic. Upward-directed light that illuminates nothing on the ground but contributes to sky glow represents pure energy waste. In the United States, a significant fraction of outdoor lighting does useful work, but a substantial portion simply bleeds into the sky, costing money and emitting carbon without providing measurable benefit. Organizations that study the problem estimate the annual cost of wasted outdoor lighting in the U.S. in the billions of dollars.

New Hampshire’s Stake in the Darkness

New Hampshire occupies an interesting position in the light pollution landscape of the Northeast. The state’s southern tier, from Nashua through Manchester to the seacoast, is substantially light-polluted, embedded in the sprawling glow of the Boston metro area. Looking south from a hill in southern New Hampshire on a clear night, the orange dome of a major metropolitan area is visible on the horizon.

The northern tier is different. The Great North Woods, which encompasses Coos County and the upper reaches of the state, is one of the least light-polluted areas in the northeastern United States. The sparsity of population, the absence of major commercial corridors, and the vast expanses of working forest and undeveloped land combine to produce skies that can still show the Milky Way on a clear, moonless night. That is a genuinely rare experience east of the Mississippi.

The NH Department of Environmental Services has noted that New Hampshire’s dark skies represent both ecological value and tourism potential. Astrotourism, the practice of traveling specifically to view dark skies, has grown substantially as urban populations have become more disconnected from natural darkness. The Great North Woods is positioned to be a destination for exactly that kind of visitor, offering an experience that is impossible to replicate in any metropolitan area.

Visit NH has published a guide to stargazing sites that includes locations in northern Coos County, the White Mountains, and the Lakes Region, acknowledging the dark sky resource as a tourism asset. That framing matters because it ties the preservation of darkness to economic incentives that local governments and businesses can act on.

Maine’s Approach and What NH Could Learn

New Hampshire’s neighbor to the east has taken a legislative step that the Granite State has not. Maine passed the first state law specifically regulating light pollution, which went into effect in January 2026. The law addresses the installation of outdoor lighting, promoting fixtures that direct light downward rather than outward and upward, a design standard that reduces sky glow without reducing safety or functionality.

New Hampshire has not moved in that direction legislatively. The state’s libertarian political culture tends toward skepticism of regulations that reach into decisions property owners make about their own land, and outdoor lighting has not emerged as a priority in the General Court. But the Maine example is a data point. A neighboring state with a similar rural character and a similar stake in outdoor tourism has decided the issue is important enough to address through law.

The practical case for action does not require a strong regulatory frame. Simple design standards for outdoor lighting, requiring full-cutoff fixtures that direct light downward rather than sideways and upward, produce measurable reductions in sky glow without any reduction in usable illumination. Municipalities that have adopted such standards report lower energy costs and better visibility in the areas being lit, alongside a measurable improvement in night sky darkness. The engineering case for better lighting design is at least as strong as the environmental one.

Darkness as a Form of Conservation

The Outside/In episode frames its argument around the concept of darkness as something that requires active preservation, not simply the absence of development. That framing is important because it reframes the issue. Conservation, in the traditional sense, involves protecting something natural from the encroachment of something human-made. Dark skies fit that definition precisely: they are a natural phenomenon being displaced by human infrastructure, in this case the cumulative output of billions of artificial lights.

New Hampshire’s environmental record includes strong commitments to land conservation, water quality, and wildlife habitat. The USDA’s reversal on the Bartlett Experimental Forest closure, the ongoing work to protect the Hubbard Brook watershed, and the state’s broad network of conserved lands all reflect a political culture that values the natural environment, even as the White Mountain National Forest faces threats from federal rollbacks to the roadless rule.

Extending that conservation ethic to the night sky would require a different kind of awareness than land or water protection, because the threat is diffuse and incremental rather than sudden and localized. No single new streetlight turns a dark sky bright. But millions of them, each seemingly minor, do. The 10 percent annual increase in sky brightness since 2011 is the cumulative product of those individual decisions, made without accounting for the collective outcome.

In the Great North Woods, the skies are still dark enough to show the universe clearly. That is increasingly a distinction, not a default. Whether it remains one depends on decisions being made now, in town halls and state houses and by property owners who may not realize the value of what their unlit acres contribute to the night sky overhead.

How fast is light pollution growing?

Since 2011, the night sky has been growing brighter at approximately 10 percent per year due to increasing artificial light. At that rate, true darkness is becoming increasingly rare, particularly in densely populated regions like the northeastern United States.

What are the environmental effects of light pollution?

Light pollution disrupts bird migration, disorients sea turtle hatchlings, interferes with insect mating cycles, and suppresses bioluminescent firefly signals. It also affects human health by disrupting circadian rhythms and suppressing melatonin production, and wastes billions of dollars in energy costs annually.

Where are New Hampshire's darkest skies?

The Great North Woods in Coos County is one of the least light-polluted areas in the northeastern United States, offering some of the region's best stargazing. Visit NH maintains a guide to stargazing sites across the state at visitnh.gov.

Has New Hampshire passed any light pollution laws?

New Hampshire has not passed legislation specifically regulating light pollution as of 2026. Maine became the first state to do so, with a law that went into effect in January 2026 requiring outdoor lighting to direct light downward rather than into the sky.

What is "astrotourism" and how does it relate to New Hampshire?

Astrotourism refers to travel specifically to experience dark skies and stargazing. New Hampshire's Great North Woods is positioned as a potential astrotourism destination because its remote, undeveloped character preserves the natural darkness that is increasingly rare in the Northeast.

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