The United Nations’ Office of Outer Space Affairs is considering issues of light pollution spanning from streetlights to satellites.


The statistics are stunning: More than 80% of the world’s population (and more than 99% of those in the U.S. and Europe) live under light-polluted skies. Most people can’t see the Milky Way. All this artificial sky glow has real impacts, affecting everything from insect reproduction to bird migration to crop yields to human health. Yet over the last 25 years, light pollution has only increased, by at least 50% overall — and in some areas, it’s up 400%.

More recently, the problem of light pollution has expanded in an unexpected way. The growing number of artificial satellites in low-Earth orbit (LEO) are increasingly adding moving lights, glints, and even diffuse glow to the night sky. Over the past two years, the number of active and defunct satellites has doubled, to a total of about 5,000 as of March 30, 2021. And companies have filed to launch tens of thousands more into orbit within the decade. While astronomers have always traveled away from civilization to reach darker skies, now satellites will streak across the fields of view of even the most rural telescopes.

Astronomers are engaging with satellite companies, such as in two conferences dubbed SATCON1 and SATCON2, which took place in the summers of 2020 and 2021, respectively. But the challenges facing satellite operators and astronomers alike are daunting.

Now, to bring the issue to a higher level — and address ground-based and space-based lights in one fell swoop — these issues are going to the United Nations. Astronomers, dark-sky advocates, industry representatives, and members of the UN’s Office for Outer Space Affairs took part in the Dark and Quiet Skies for Science and Society workshop on October 3–7, 2021. (The conference was virtual, not because of COVID-19 but because of an active volcano in La Palma, Spain, which was where the workshop was to have taken place.)


Reducing light pollution doesn’t have to mean eliminating lights; outdoor lighting just needs to be directed where it is needed, when it is needed. And critically, any outdoor lights should be amber-colored, rather than the white/blue LEDs that disrupt the circadian rhythms of humans and wildlife alike.

Simple enough, right? So why aren’t we doing these things? Some individual cities have instituted dark-sky lighting ordinances. Pittsburgh, Pennsylvania, did so recently, and Tucson and Flagstaff in Arizona have and continue to implement even stricter measures in place, in part to protect nearby observatories. Representatives from Morocco and China gave updates during the conference on dark-sky efforts, and Andreas Hänel (Dark Sky Germany) reported that his country has particularly strong participation in dark-sky measures.

While such grass roots actions are difficult to implement and unevenly distributed, they also provide crucial examples to guide broader policies. “You want best practices that can be applied internationally, unilaterally, for all satellites,” suggested space diplomat Peter Martinez. “Use the outcomes of bottom-up efforts as inputs to move toward a set of international guidelines that could be adopted by the UN General Assembly.”

However, the secretary of the Committee on the Peaceful Uses for Outer Space (COPUOS), Niklas Hedman, cautioned that the committee might not consider ground-based light pollution as part of their purview. “We have to be careful so COPUOS doesn’t dismiss it,” he said at a final roundtable.

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