Summary: A diverse group of the world's light pollution experts recently met at the Artificial Light At Night 2023 conference. The main themes of the conference and important results presented there are reviewed, giving a sense of the research community's current direction.

Many of the world's experts on light pollution recently met in Calgary, Canada, to discuss their latest findings. The Eighth International Conference on Artificial Light At Night (ALAN) was held in Calgary, Canada during 11-13 August 2023. We were there to learn about recent research results and new directions that ALAN science is heading.

The ALAN conference series began in 2013. Starting with the 2018 edition, it occurs every other year, alternating with the Light Pollution: Theory, Modeling and Measurement conference. This year's edition saw its highest level of participation from the largest number of countries ever. 108 people attended in person on the University of Calgary campus and about 50 participated as virtual delegates. 

This year’s attendees represented every populated continent except Africa. The participants represented some 28 countries. One-third of attendees were students, many of whom study ALAN as part of their graduate thesis or dissertation work. Despite some computer networking issues, virtual participation in the conference seemed strong. Besides to the in-person event in Calgary, a virtual poster session took place in late July using the Gather.town environment online.

The ALAN Steering Committee accepted so many of the submitted abstracts that much of the in-person event ran in two parallel sessions. The broad topical content of the tracks was ALAN impacts on wildlife and ecology, and measurements and monitoring of light pollution. These tracks reflect where the majority of the research interest (and funding) are at this point in the field's history. There were fewer presentations about social science and public policy than in past years.

Land acknowledgements were a frequent part of the proceedings. Former Calgary city councilor Brian Pincott explained that this is part of the ongoing truth and reconciliation process in Canada. "We have a lot to do to make sure our future includes everyone," Pincott said during his conference wrap-up on Sunday afternoon.

Jennifer Howse (University of Calgary) gave the banquet talk, "Reclamation Under Alberta Skies", on Saturday night. Howse, a Métis woman, used her time to bridge the worlds of her Indigenous and European ancestry with the modern world in the context of her dark-sky work.  She noted the importance in many Indigenous cultures of asking the question “How will people in seven generations live?” Howse also advised listeners to ponder that question in light of our activities that impact space and the night sky.

It reminded attendees that the next frontier of dark-sky conservation involves social and environmental justice concerns. Diane Turnshek (Carnegie Mellon University) raised the issue of the increasing number of people who have never seen the Milky Way. It is therefore challenging to communicate with them about starry skies when this is not something they have directly experienced.  Waleska Valle (Adler Planetarium) spoke about her experience working with youth in Chicago to identify the ways in which light pollution impacts their communities. And Doug Sam (University of Oregon) used the International Dark Sky Park designation effort at Mesa Verde National Park as a case study to examine such efforts through the theoretical framework of decolonization. “When we designate future IDSPs, we must involve native peoples as a matter of justice," Sam explained. 

As usual, the scientific presentations were all high-quality and stimulated lively discussion. The main takeaways from the posters and talks include:
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• The research community needs standardized protocols for measuring ALAN and reporting data, but we seem no closer to deciding on what those are.
• Our measurement devices are still far from perfect and some show signs of aging in the field.
• Yet as devices and software improve, we are learning more about the detailed distribution of ALAN in 3-D, particularly in urban contexts.
• Understanding how animals behave due to a given lighting environment is of foundational importance to ecological studies of ALAN.
• At the same time, the evidence for ecological harms associated with ALAN exposure continues to mount.
• The next frontier of dark-sky conservation practice involves social and environmental justice concerns.
• As the global population ages, we need to rethink why and how we light our world and so do in a way that is inclusive of the amount of “visual diversity” that now exists.
• Further engagement with those exploring ALAN issues from perspectives from the humanities would benefit the research community.

​Friday night saw a successful public outreach event put on by the ALAN conference in coordination with the Royal Astronomical Society of Canada Calgary Centre. About 300 people attended the event, which included an introductory talk about light pollution and a panel discussion with researchers. Afterward, attendees could view the night sky through telescopes set up on the University of Calgary campus.

As participants began to disperse and head home beginning on Sunday, many reported how refreshing the experience was. ALAN 2013 was the first in-person conference in the series since 2018. The  onset of the COVID-19 pandemic in 2020 caused the organizers to pivot to an online-only format.

For many, the Calgary conference was the first time they saw their colleagues in person since 2019. Given that the research community is still small, the ALAN conferences feel more like village assemblies. A return to meaningful, in-person interactions supports the kind of collegiality that constantly draws students who want to make a career of night studies. It also supports collaborations that become friendships while yielding high-quality research results that push the field ahead. 

It is traditional to name the next host city at the conclusion of ALAN. On Sunday, attendees learned that the next meeting will be held in County Mayo, Republic of Ireland, in October 2025. Already many look forward to their next opportunity to present their work, reunite with old friends and meet new ones. 

The natural night sky looms large over humanity's past, present and future. Once a province only of the gods, the night sky is now our portal to understanding the universe. Light pollution, a phenomenon of only the last two centuries, now threatens to separate much of humanity from the starry heavens. Should access to a night sky unspoiled by light pollution be reserved only to those who live, or can travel to, rural places? Or should we aspire to a world that affords such access to all? 

​There are many reasons why people work toward preserving dark night skies. As our window on the cosmos, the night sky is the source of information that fuels astronomy. "Astrotourists" travel around the world unique experiences under the stars. Closer to home, casual stargazers find recreation opportunities under almost any skies.

We know that actions taken to protect the night sky have myriad benefits on the ground, too. Light pollution has negative effects on most wildlife species.  Darker places, on the other hand, offer refuge to plants and animals already stressed by habitat loss and climate change. Better outdoor lighting can also improve public safety while using less energy. Taken altogether, these are powerful reasons for reducing light pollution.

But if we set all that aside, there's an equally strong argument that access to the night sky has a prominent place in what it means to be human. Dark night skies were once accessible to all people in the world, and they inspired great works of art, literature and music. The sky is part of the cultural heritage of all humanity. It's one of the few aspects of the natural world that we all share.

As such, it may be true that all people should have equal access to the stars. If so, then light pollution is more than an environmental threat. It interferes with access to an important cultural resource.

To date there is little recognition in law for these ideas. Many of the assertions about humanity's rights come from the United Nations. A few UN-sponsored activities have either implied a right to access the night sky or called for it outright. For example, Article 1 of the the La Laguna Declaration of 1994  asserts that “persons belonging to future generations have the right to an uncontaminated and undamaged Earth, including pure skies.”

The United Nations Educational, Scientific and Cultural Organization (UNESCO) held a conference on these ideas in 2007. The resulting "Declaration in Defense of the Night Sky and the Right to Starlight" considers "an unpolluted night sky" to be "an inalienable right of humankind". The Declaration elevates the right to starlight to a place alongside "all other environmental, social, and cultural rights".

Another relevant UN statement is the 1972 UNESCO Convention for the Protection of the World Cultural and Natural Heritage. This action established the UNESCO World Heritage Programme. It has applied the label to astronomy sites, both ancient (e.g, the Chankillo Archaeoastronomical Complex, Peru) and modern (e.g., Jodrell Bank Observatory, UK). But so far it has resisted designating the night sky, or nighttime landscapes.

The night sky is both cultural and natural heritage. It transcends national boundaries; there is, for instance, no "American sky" or "Chinese sky" belonging to those cultures alone. And it’s not a problem that the night sky, or space, is an “intangible” thing. UNESCO already recognizes such forms of cultural heritage. Under the existing framework, the night sky could receive the same kind of recognition and protection as any object the UN recognizes.

The uses of outer space are now beginning to affect the quality of night skies on Earth. The space over our heads is increasingly crowded, with the planned launch of hundreds of thousands of new satellites in the 2020s. These satellite "megaconstellations" are gradually transforming the appearance of the night sky. And yet the main international treaty governing the use of space is silent on the subject. When the nations of the world signed the Outer Space Treaty in 1967, these concerns were on no one's radar.

Threats to human health from the pollution of air, water and soil can dictate measures to reduce those pollutants. There is an emerging consensus among researchers that nighttime darkness is key to our health and wellbeing. Reasons exist suggesting that regular access to nature is good for us. And there's even evidence of disparities in the way light at night affects poor neighborhoods and communities of color.

Does nature itself have some say in all this? Nations have begun to recognize certain "rights of nature" that can lead to rehabilitation of environmental harms. That's true even when no real person has suffered any obvious injury. Touted as a legal means to combat climate change, it's possible the same principles apply to night-sky conservation.

In an era when so much divides us, whether neighbor versus neighbor of culture versus culture, the night sky is something we all share. Over time, we may come to realize that seeing the stars is not only something of value to people who can afford to escape the nighttime glow of the world's cities. Rather, it's an integral part of the human experience that should be available to all. Solving the global problem of light pollution is simple and cost effective. And it just might make all of our nights a little better.

There are many ways to bring back the stars to the places where we live, work and play. Contact us today to find out how we can help.

Already people were beginning to see the effects of artificial light at night. Yet until very recently, we really didn't have a good understanding of how harmful those effects could be.

Today, we understand that the issue of light pollution is much more than about whether we can see the night sky. It touches on all these subjects:
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• Biology and ecology: Light exposure impacts almost every species studied by scientists. It interferes with their biology and changes how they interact with the environment. This harms ecosystems and can make plants and animals less resilient to environmental changes.
  
  

• Human health: Scientific data establish a link between light exposure and human health consequences. Studies are often conducted in laboratory settings that can misrepresent conditions in the real world. We must use great caution to properly understand research results.
  
  

• Public safety: The belief that outdoor lighting improves traffic safety and discourages or prevents crime is common. It may explain in part the rapid growth in the use of outdoor light in recent years and decades. There are cases where careful application of outdoor light at night may improve nighttime safety. But there is no general benefit supported by scientific evidence.
  
  

• Energy and climate change: Wasted outdoor light at night is wasted energy. The world remains highly dependent on fossil fuels to generate electricity. Since light pollution represents a waste of energy, it also contributes to climate change.
  
  

There is still much about light pollution we don't know. For instance, we have little information about how light affects people in social contexts. Local governments may use light in ways that affect neighborhoods according to the race of the people who live in them. That would make light use a matter of social and environmental justice.

At the same time, we shouldn't forget the allure of the stars. Early evidence suggests that 'astrotourism' is a growth industry that may see an explosion of interest as the Covid-19 pandemic eases. It can be an engine of economic development activity in rural areas, but only if skies there remain dark. And new concerns, like light pollution from satellites, continue to emerge.

The diversity of effects caused by light pollution means there's something for everyone in the dark-skies movement. Some participants know little about astronomy but care deeply for better nighttime visibility. Concern for wildlife motivates others. And even those for whom breaking down barriers in society is a priority are coming to see lighting as an important consideration.

Whether it's to see more stars, improve community safety at night or make conditions better for the ecology, pursuit of dark skies is key. Contact us today to find out how we can help achieve your goals.