International Dark-Sky Association Research Articles

Alleviate light pollution by recognizing urban night-time light control area based on computer vision techniques and remote sensing imagery

Light pollution caused by unreasonable and excessive use of outdoor artificial light at night (ALAN) has become one of the fastest growing and most urgent global environmental problems. Therefore, the International Dark-Sky Association advocated the more controlled use of ALAN in urban area to protect night-time environment and enable sustainable development. However, relevant research and lighting planning are still in the enlightenment stage. This study focused on a typical city experiencing significant ALAN growth, combining night-time remote sensing imagery, urban big data and other muti-source heterogeneous data to systematically research urban night-time light status. We first analyzed the spatio-temporal evolution pattern of ALAN. Subsequently, advanced computer vision algorithms were proposed to recognize the night-time light control area (NLCA) based on the perspective of supply and demand balance. Results suggest both the ALAN intensity and area have grown rapidly over the past decade in the study area, with the intensity increasing by 82 % and the area expanding by 42 %. And a 108.5-square-kilometre area of the NLCA was intelligently delineated, for where the ALAN intensity was more than the demand of population, indicating that the management of the night-time light environment an urgent matter. Therefore, this study proposed practical management solutions according to the different functional zones in city within the NLCA, for further promoting the green transformation and smart upgrading of urban outdoor lighting. To sum up, our research offers a novel approach to resolving the issue of urban light pollution by recognizing the NLCA, as well as facilitating energy conservation and emission reduction.

Dark Sky Parks: public policy that turns off the lights

Dark skies are culturally, ecologically, and economically valuable natural resources but little has been written on how dark sky conservation is being enacted through environmental policy and legislation. Using the Multiple Streams Framework and qualitative data from over 300 policy documents, we characterize the problems, policy solutions, and politics around protecting night sky resources. We find that the core public policy problem of diminishing night skies is perceived by stakeholders to be light pollution produced from surrounding urban development. To address this problem, decision-makers enact policy solutions of creating Dark Sky Parks on protected landscapes with rigorous and scientific processes. These technical ideas for creating Dark Sky Parks are transmitted to decision-makers at park and landscape scales. Dark sky conservation is a political process as well, which attracts bipartisan support from policy-makers from different political parties due to the economic potential of astrotourism. Our work has general applications for the role of managers and NGOs in creating science policy, engaging the public, and enacting policy change, as was seen in the context of the International Dark Sky Association providing resources, technical information, and support for managers and other stakeholders to encourage actions at various scales to protect rapidly-disappearing dark skies.

Mitigating urban light pollution: A review of municipal regulations and implications for planners

ABSTRACT Propelled by more energy-efficient technologies such as light-emitting diodes, the growth of outdoor light at night is raising concerns about light pollution (LP). Given mounting evidence of LP’s risks to human wellbeing, nature and wildlife, and views of the dark sky, this paper examines the extent to which LP concerns are addressed in land use plans, policies, and regulations in nine U.S. cities, including Flagstaff, Arizona, a city known for its model lighting code. Through a review of zoning and other ordinances, area and sectoral plans and policies, media reports, and interviews with planners, this study documents that LP has yet to be taken seriously in municipal codes of most study cities. Drawing from the Flagstaff model, it offers recommendations for evidence-based, objective standards for three key dimensions of LP-mitigation: limiting total illumination or lumens per acre, shielding of lamps, and specifying luminaire characteristics. ABBREVIATIONS AMA: American Medical Association; APA: American Planning Association; CCT: Correlated Color Temperature; CRI: Color Rendition Index; ESCO: Energy Service Companies; f.c.: foot candle; HPS: High-Pressure Sodium; IDA: International Dark-Sky Association; LED: Light-Emitting Diode; LP: Light Pollution; LPS: Low-Pressure Sodium; LZ: Lighting Zone; NSA: Narrow-Spectrum Amber

Aenos International Dark-Sky Park: The first officially designated area protected from light pollution in Greece

The scope of this work is to analyse the methodology used for the official designation of the first International Dark-Sky Park in Greece which was Aenos National Park, designated in May 2023. The methodology was based on the official International Dark-Sky Park requirements of the International Dark-Sky Association with many differentiations due to specific technical challenges and administrative circumstances in Greece. The process included both technical works, light measurements, lighting retrofit as well as administrative, social and publicity activities. From beginning to completion, the designation process lasted more than three years and required hundreds of manhours to be completed. The official designation of Aenos International Dark-Sky Park provides an important opportunity for the protection of the skies of Greece from light pollution both as a case study and inspiration as well as a solid example used to push for the dark sky protection agenda which is part of a sustainable

STRATEGIC DEVELOPMENT OF ASTROTURISM IN THE REPUBLIC OF CROATIA – COMPARATIVE ANALYSIS

The paper investigates the issue of strategic development of a new selective form of tourism that is growing in many countries around the world named astrotourism. The issue of light pollution is also considered, given that a clear starry sky is a fundamental prerequisite for the development of this selective form of tourism. The aim of this paper is to investigate the level of development of astrotourism in the Republic of Croatia. For this purpose, a comparative analysis was performed targeting selected astrotourist destinations - the so-called Dark-Sky Parks in Croatia and Europe, as well as a research focusing on the geographical distribution and number of certified sky parks in the world. Certified Dark-Sky Parks are typical astrotourism destinations that meet all the prerequisites for its development, and are awarded the official certificate issued by the IDA - International Dark-Sky Association, as the world's umbrella institution dealing with light pollution. Observatories have a special role in the development of astrotourism, so the proposed paper presents an overview of observatories in Croatia that are focused on this type of activities. The paper aims to sensitize the scientific and professional public regarding the issue of light pollution, but also to encourage further research and expert discussions relating to this topic. Astrotourism combines different components and functions – a scientific and a recreational one, but also a very important ecological and educational function, encouraging special discussions and proposals focusing on solutions for the sensitive but still insufficiently researched area of light pollution, inadequate public illumination, as well as other “unhealthy” forms of illumination.

Landscape Potential and Light Pollution as Key Factors for Astrotourism Development: A Case Study of a Slovak Upland Region

Astrotourism is considered to be a modern form of ecotourism. The main resource for astrotourism is a high-quality night sky, but this is very sensitive to natural as well as anthropogenic factors; for example, land utilization and expansion of urban areas often cause the negative effect of light pollution. The aim of the study is to perform a lighting survey by night sky brightness (NSB) measurements using the sky quality meter (SQM-L) at 20 study sites of the Slovenské stredohorie Upland region (Slovakia) and to assess the region’s potential for astrotourism development (PAD) using a multicriteria analysis. The NSB values ranged from 19.90 (city Žiar nad Hronom at Žiarska kotlina Basin) to 21.54 mag/arcsec2 (recreation area Poľana at Poľana Mountains). At 14 out of 20 study sites, the NSB values even reached 21.2 mag/arcsec2, as recommended by the International Dark-Sky Association for dark-sky parks. Four study sites were categorized as sites with medium PAD, and sixteen with low PAD. No study site reached a high or very high PAD. The best conditions for astrotourism development are fulfilled mainly by the Poľana Mountains geographical unit. The findings can be used for sustainable astrotourism development, land management, and planning to ensure socioeconomic development, together with nature and dark-sky conservation.

Analysis of Light Pollution in Ticino region during the period 2011-2016

Since 2002, the Environmental Observatory of Southern Switzerland (OASI) has monitored a remarkable set of environmental parameters with the purpose of performing an enhanced observation of the regional environmental conditions. Since 2011, a campaign for the supervision of the artificial nighttime skyglow has been included in the OASI monitoring system exploiting the collaboration with DarkSky association. This network monitors the light pollution in several areas of Ticino, the southernmost Swiss Canton bordering Italy. It consists of multiple stations, which continuously measure the sky brightness. The University of Applied Sciences and Arts of Southern Switzerland, in collaboration with Politecnico di Milano, introduces the results of a study regarding the skyglow evolution during the period 2011-2016. The time-series of the OASI network were pre-processed to detect and discard data affected by natural perturbing events, such as moon and clouds presence and sun effect during twilights. In a second time, a distribution analysis of the data and an evaluation of the brightness trend during the considered period were performed. The results show that light pollution in Ticino is strictly influenced by the northern area of the nearby Italian Lombardy region and that during the surveyed years a decreasing of the pollution occurred.

Living Environmental Laboratory for Lighting: Reduction of Light Pollution at Hungarian Settlements

The International Dark Sky Association has a flight of rules for public lighting in dark sky parks. In Hungary, many settlements still illuminate with compact fluorescent lights and sodium lamps, that do not fulfill these rules. In our research project, financed by a grant of the European Union, we established a system of Living Environmental Laboratory for Lighting at two settlements in dark sky parks in Hungary. As the first step, the public lighting system was reconstructed, so that it satisfied the rules of IDA. We designed new LED luminaires with optimal illumination and optical properties to provide the necessary luminous intensity and reduce light pollution at the same time. The new system has a two-step illumination profile: (i) Early night, after sunset, when the traffic is still high, warm white LEDs are applied to ensure sufficient lighting coming to the roads and pavements with a wide beam of light. (ii) Late night, when the traffic is low, the illumination switches to amber LEDs that have a narrower light beam to minimize light pollution and provide sufficient visibility. This approach can be an optimal illumination construction to reduce the light pollution of public lighting at night.

КУЛЬТУРА ЗОВНІШНЬОГО ОСВІТЛЕННЯ. ПРОБЛЕМА СВІТОВОГО ЗАБРУДНЕННЯ НАВКОЛИШНЬОГО СЕРЕДОВИЩА

КУЛЬТУРА ЗОВНІШНЬОГО ОСВІТЛЕННЯ. ПРОБЛЕМА СВІТОВОГО ЗАБРУДНЕННЯ НАВКОЛИШНЬОГО СЕРЕДОВИЩА

Siting of Dark Sky Reserves in China Based on Multi-source Spatial Data and Multiple Criteria Evaluation Method

With the rapid development of population and urbanization and the progress of lighting technology, the influence of artificial light sources has increased. In this context, the problem of light pollution has attracted wide attention. Previous studies have revealed that light pollution can affect biological living environments, human physical and mental health, astronomical observations and many other aspects. Therefore, organizations internationally have begun to advocate for measures to prevent light pollution, many of which are recognized by the International Dark-Sky Association (IDA). In addition to improving public awareness, legal protections, technical treatments and other means, the construction of Dark Sky Reserves (DSR) has proven to be an effective preventive measure. So far, as a pioneer practice in this field, the IDA has identified 11 DSRs worldwide. Based on the DA requirements for DSRs, this paper utilizes NPP-VIIRS nighttime light data and other multi-source spatial data to analyze possible DSR sites in China. The land of China was divided into more than ten thousand 30 km × 30 km fishnets, and constraint and suitable conditions were designated, respectively, as light and cloud conditions, and scale, traffic and attractiveness conditions. Using a multiple criteria evaluation, 1443 fishnets were finally selected as most suitable sites for the construction of DSRs. Results found that less than 25% of China is not subject to light pollution, and less than 13% is suitable for DSR construction, primarily in western and northern areas, including Tibet, Xinjiang, Qinghai, Gansu and Inner Mongolia.

Testing for changes in light emissions from certified International Dark Sky Places

The International Dark-Sky Places (IDSP) program of the International Dark-Sky Association is a voluntary certification in which communities commit via legislative changes to move towards more sustainable lighting that reduces light pollution. As over 115 IDSP have now been certified, it is interesting to ask the extent to which this certification results in reduced light emissions. In this paper, we compared trends in upward light emission of 98 communities located in or near IDSP to those of 98 similarly sized communities further away from the IDSP, using a night lights observing satellite (the Visible Infrared Imaging Radiometer Suite Day-Night Band). The current dataset is not sufficient to distinguish the hypothesis that IDSP certification results in a lower rate of change in upward light emissions from the null hypothesis that IDSP certification has no impact. This result is with regard to upward light emissions only: it is possible that certification has resulted in decreases in night sky brightness that the satellite is not able to observe.

Outcomes from the IYL2015 Quality Lighting Teaching Kit Program: Reaching for the Stars

Poor quality lighting not only impedes astronomy research and our right to see a starry night sky, but creates safety issues, affects human circadian sensitivities, disrupts ecosystems, and wastes billions of dollars/year in energy consumption. It also leads to excess carbon emissions. How do you change the mindset of society that is used to turning night into day? You educate the next generation on quality lighting. As an outcome of the International Year of Light 2015, the U.S. National Optical Astronomy Observatory’s Education and Public Outreach group has produced a Quality Lighting Teaching (QLT) Kit. The kits are designed around problem-based learning scenarios. The kit’s six activities allow students to address real lighting problems that relate to wildlife, sky glow, aging eyes, energy consumption, safety, and light trespass. The activities are optimized for 11-14 year olds, but can be expanded to younger and older. All materials are in English and Spanish. Most of the activities can be done within in a few minutes during class or afterschool in the form of stations or as stand-alones. Everything one needs for the six activities is included. Tutorial videos on how to do the activities can be found at www.noao.edu/education/qltkit.php. Ninety-two kits have been distributed to 32 countries with the help of SPIE–The International Society for Optical Engineering, CIE–International Commission on Illuminations, OSA–The Optical Society, IDA–the International Dark Sky Association, and the IAU OAD–Office of Astronomy Development. Highlights from the initial program evaluation will be discussed.

Systematic measurements of the night sky brightness at 26 locations in Eastern Austria

We present an analysis of the zenithal night sky brightness (henceforth: NSB) measurements at 26 locations in Eastern Austria focussing on the years 2015–2016, both during clear and cloudy to overcast nights. All measurements have been performed with ‘Sky Quality Meters’ (SQMs). For some of the locations, simultaneous aerosol content measurements are available, such that we were able to find a correlation between light pollution and air pollution at those stations. For all locations, we examined the circalunar periodicity of the NSB, seasonal variations as well as long-term trends in the recorded light pollution. The latter task proved difficult, however, due to varying meteorological conditions, potential detector ‘aging’ and other effects. For several remote locations, a darkening of the overcast night sky by up to 1 magnitude is recorded – indicating a very low level of light pollution –, while for the majority of the examined locations, a brightening of the night sky by up to a factor of 15 occurs due to clouds. We present suitable ways to plot and analyze huge long-term NSB datasets, such as mean-NSB histograms, circalunar, annual (‘hourglass’) and cumulative (‘jellyfish’) plots. We show that five of the examined locations reach sufficiently low levels of light pollution – with NSB values down to 21.8 magSQM/arcsec2 – as to allow the establishment of dark sky reserves, even to the point of reaching the ‘gold tier’ defined by the International Dark Sky Association. Based on the ‘hourglass’ plots, we find a strong circalunar periodicity of the NSB in small towns and villages ( < 5.000 inhabitants), with amplitudes of up to 5 magnitudes. Using the ‘jellyfish’ plots, on the other hand, we demonstrate that the examined city skies brighten by up to 3 magnitudes under cloudy conditions, which strongly dominate in those cumulative data representations. Nocturnal gradients of the NSB of 0.0–0.14 magSQM/arcsec2/h are found. The long-term development of the night sky brightness was evaluated based on the 2012–17 data for one of our sites, possibly indicating a slight ( 2%) decrease of the mean zenithal NSB at the Vienna University Observatory.

Light pollution: spatial analysis and potential ecological effects in rural Ireland

Increasing use of artificial light at night has led to many areas across the globe being exposed to light conditions above the natural background level. Research is only now uncovering the impacts of ‘ecological light pollution’ on the environment. Artificial light at night can disrupt circadian rhythms, cause interference with orientation and migration, alter predator/prey interactions and affect other behaviour and physiological features. Intercalibration of Defense Meteorological Satellite Program’s Operational Linescan System images shows that night light emissions in Ireland have increased significantly from 1995 to 2010. In this period, artificial light has spread into previously dark rural areas, including County Mayo where 28% of land surface is designated for habitat and species conservation purposes. To investigate light pollution in rural areas, examination into the conservation area of Owenduff/Nephin Beg Complex was undertaken. Spatial analysis of light measurements taken from Sky Quality Meters surrounding the site were overlaid with species distribution records to determine the proximity of protected species to sources of artificial light at night. Light measurements from the area show pristine night skies according to International Dark Sky Association standards, with one site indicating the presence of localised light pollution. Further work is required to determine if any potential adverse ecological impacts on protected species in the locality are occurring from artificial light at night. The findings of this study provide a foundation for ecological light pollution effects assessment in Ireland. Further work is required to establish the temporal and spatial scales of artificial light in Irish rural areas and determine the specific effects on species present there.

Light pollution: spatial analysis and potential ecological effects in rural Ireland

Increasing use of artificial light at night has led to many areas across the globe being exposed to light conditions above the natural background level. Research is only now uncovering the impacts of ‘ecological light pollution’ on the environment. Artificial light at night can disrupt circadian rhythms, cause interference with orientation and migration, alter predator/prey interactions and affect other behaviour and physiological features. Intercalibration of Defense Meteorological Satellite Program’s Operational Linescan System images shows that night light emissions in Ireland have increased significantly from 1995 to 2010. In this period, artificial light has spread into previously dark rural areas, including County Mayo where 28% of land surface is designated for habitat and species conservation purposes. To investigate light pollution in rural areas, examination into the conservation area of Owenduff/Nephin Beg Complex was undertaken. Spatial analysis of light measurements taken from Sky Quality Meters surrounding the site were overlaid with species distribution records to determine the proximity of protected species to sources of artificial light at night. Light measurements from the area show pristine night skies according to International Dark Sky Association standards, with one site indicating the presence of localised light pollution. Further work is required to determine if any potential adverse ecological impacts on protected species in the locality are occurring from artificial light at night. The findings of this study provide a foundation for ecological light pollution effects assessment in Ireland. Further work is required to establish the temporal and spatial scales of artificial light in Irish rural areas and determine the specific effects on species present there.

Going for the Gold : Quantifying and Ranking Visual Night Sky Quality in International Dark Sky Places

Since the invention of electric lighting in the nineteenth century, the steadily increasing use of artificial light at night in outdoor spaces has grown to threaten the integrity of dark night skies and nocturnal terrestrial spaces. The conservation community has gradually come to accept the need to protect natural nighttime darkness, which finds expression in dark sky parks and similar protected areas. As these places begin to reap tangible economic benefits in the form of sustainable ‘astrotourism,’ the movement to actively protect them gains strength. The International Dark-Sky Association designates Dark Sky Parks and Reserves under a comparative ranking scheme that assigns night sky quality tiers according to a combination of objective and subjective characteristics, but shortcomings in the consistency of these ratings exist that undermine the consistency and reputation of the designation program. Here we consider potential changes to the qualification regime to make the ratings system more robust for the benefit of future designations.

Sky brightness levels before and after the creation of the first International Dark Sky Reserve, Mont-Mégantic Observatory, Québec, Canada

In 2007, the area around the Mont-Mégantic Observatory (MMO) was officially certified by the International Dark-Sky Association and the Royal Astronomy Association of Canada as the first International Dark Sky Reserve (IDSR). In order to be able to investigate the impact of Artificial Light at Night on night sky brightness before and after the establishment of the IDSR, we used a heterogeneous artificial sky brightness model including an implicit calculation of 2nd order scattering (ILLUMINA) developed by Martin Aubé׳s group. This model generates three kinds of outputs: the sky radiance at the given site, observing angle and wavelength and the corresponding contribution and sensitivity maps. The maps allow for the identification of the origin of the sky radiance according to each part of the surrounding territory. For summer clear sky conditions, the results show that replacing light fixtures within a 25km radius around the MMO with cut-off High Pressure Sodium devices and reducing the total installed radiant power to ~40% of its initial level are very efficient ways of reducing artificial sky brightness. The artificial sky brightness reduction at zenith observed after the establishment of the IDSR was ~50% in the 546nm mercury spectral line, while the reduction obtained in the 569nm sodium line was ~30%. A large part of that reduction can be associated to the reduction in radiant power. The contribution and sensitivity maps highlight critical zones where any changes in the lighting infrastructure have the most important impact on sky brightness at the MMO. Contribution and sensitivity maps have been used to analyze the detailed origin of sky brightness reduction. The results of this study are intended to support authorities in the management of their lighting infrastructure with the goal of reducing sky brightness. The results have been shared with MMO officials and are being used as a tool to improve sky quality at the observatory.

Summaries of SpS17 Discussions IAU GA 2012 Special Session on Light Pollution

To address light pollution issues, IAU Commissions 41, 46, 50, and 55 are involved in getting the word out to the public and IAU members via cultural, educational, technical; however, efforts can always improve and evolve. To carry out a successful light pollution abatement program supported by the IAU, it takes a diversity of groups, professions, and disciplines with their collective knowledge and experience. In manifesting dark skies awareness effectively, we are stronger together than we are alone; therefore, combining efforts of Commissions 41, 46, 50 and 55 with organizations like the International Dark-Sky Association, Astronomers Without Borders, The World at Night and partnering with events like Earth Hour or GLOBE at Night is a good step forward.

A new Starlight Reserve for the central South Island of New Zealand

AbstractThe Aoraki Mackenzie International Dark Sky Reserve is a new reserve created in 2012 by the International Dark-Sky Association in the central South Island of New Zealand, and covers over 4300 square kilometres around Mt John University Observatory. It is the first such reserve to be recognized at gold tier level and is the largest dark sky reserve in the world. Astro-tourism in the new reserve will be a prominent activity in the coming years.

Losing the Dark: A Planetarium PSA about Light Pollution

AbstractLosing the Dark is a six-minute PSA video created for fulldome theaters by Loch Ness Productions, the International Dark Sky Association Education Committee headed by Dr. Constance Walker of the National Optical Astronomy Observatories, Dome3, Adler Planetarium, and Babak Tafreshi (The World at Night). It explains light pollution, its effects, and ways to implement “wise lighting“ practices to mitigate light pollution. The show is also made in flat-screen HD format for classical planetariums, non-dome theaters, and for presentatons by IDA speakers.