Satellite Observations Show Reductions in Light Emissions at International Dark Sky Places During 2012-2020

Hyde et al. previously examined the trends in light emission measured by satellite for 98 communities located in or near areas certified as “International Dark Sky Places” (IDSP), and did not find evidence of a difference in trends in comparison to 98 communities of similar size located further away. Here we re-examine the satellite dataset, making use of a newly available correction for the radiance of atmospheric airglow, and extending the analysis period by an additional two years. The new dataset is consistent with the hypothesis that light emissions tend to decrease in communities in or near certified IDSP (median value of -1.6% per year), and is in tension with the hypothesis that there is no difference between these communities and others located further away (median increase of +0.1% per year). While the null hypothesis of no difference in the certified regions still cannot be entirely ruled out (Kolmogorov-Smirnov test probability of 2.5%), it appears likely that IDSP certification is associated with changes in light emissions.

Dark Acupuncture

This paper outlines a research methodology and design strategy aimed at realizing sustainable lighting within (sub)urban multi-functional parks. It does so by detailing the research process, as well as resultant vision and design concepts, for the Delftse Hout (a park in Delft, The Netherlands). This process included formulating value-level design requirements, undertaking a detailed site-study to understand stakeholder needs, and combining these to provide conceptual and practical grounding for the future development of a lighting masterplan. A key – and we argue generalizable – outcome of the process is the development and application of dark acupuncture, a scalable design strategy aimed at strategically-placed interventions of darkness and illumination. The paper thus provides three contributions to sustainable lighting theory and practice: a detailed case study of innovative lighting design research; the refinement of dark acupuncture as a design strategy for nature-inclusive park lighting (which itself can be more broadly applicable to urban lighting policy and design); and, as a practical example of transdisciplinary research into artificial light at night.

Can we illuminate our cities and (still) see the stars?

Could we enjoy starry skies in our cities again? Arguably yes. The actual number of visible stars will depend, among other factors, on the spatial density of the overall city light emissions. In this paper it is shown that reasonably dark skies could be achieved in urban settings, even at the center of large metropolitan areas, if the light emissions are kept within admissible levels and direct glare from the light sources is avoided. These results may support the adoption of science-informed, democratic public decisions on the use of light in our municipalities, with the goal of recovering the possibility of contemplating the night sky everywhere in our planet.

The GONet (Ground Observing Network) Camera: An Inexpensive Light Pollution Monitoring System

Instrumentation developed to monitor and characterize light pollution from the ground has helped frame our understanding of the impacts of artificial light at night (ALAN) [Bará, Lima, & Zamorano, 2019; Hänel et al., 2018; Zamorano et al., 2017]. All-sky imaging has been used to quantify and characterize ALAN in a variety of environments [D. M. Duriscoe, 2016; Jechow, Kyba, & Hölker, 2019]. Over the past decade growth in access to DIY electronics has afforded the opportunity for the development of new and affordable instrumentation for ALAN research. The GONet (Ground Observing Network) camera is an inexpensive (~USD 100), simple to use, all-sky imaging system designed to allow measurements of sky quality at night. Due to their ease of use and low price, GONet cameras allow observations by users with little technical expertise, large inter-comparison campaigns and deployments of opportunity. Developed as a student engineering project at the Adler Planetarium, initial field tests of the GONet system have demonstrated its utility as a tool that can benefit ALAN research. Here we present an overview of the design and use of the GONet device, methods of calibration, initial results from observations, potential use cases, and limitations of the system. What we describe here is the version 1 GONet camera. We conclude with a brief description of the version 2 unit already under development.

LuMinAves: cooperative research and mitigation of light pollution impacts in seabirds

Any efforts to conduct a sustainable management of urban and natural landscapes benefit from an interdisciplinary approach and active collaboration between actors, thus increasing the feasibility and effectiveness of the proposed actions. With the emergent transition of urban lighting to white LED technology, such shifts can bring a variety of negative effects to these environments, thus such actions should be applied taking into account as broad a knowledge set as available. These are often fragmented and incoherent thus in need of actions which unite them into usable and common tools. In the North Atlantic region of Macaronesia, a project has been implemented which uses the negative effects light pollution has on seabird populations as a base to effect changes in the regional lighting schemes, decreasing light pollution and increasing the sustainability of the current LED transition, improving practices and awareness, to the benefit of both seabirds and human populations alike.

Light Pollution Mapping from a Stratospheric High-Altitude Balloon Platform

The NITELite (Night Imaging of Terrestrial Environments Lite) system is a method of collecting regional-scale light emissions data from a latex high-altitude balloon (LHAB) platform. An LHAB can reach altitudes of 25-30km from where the nighttime imaging is performed. LHAB missions are relatively low cost (<$2000US/flight) and easy to repeat. A NITELite mission collects data with high resolution (<10m/px), color information (RGB) over a region of thousands of square kilometers. This system provides a new source of data for remote sensing of artificial light at night (ALAN) research, filling the data gap between aerial and satellite observations. Nighttime LHAB-based imaging can provide data to support fields of ALAN research such as observation of real-time variability, monitoring effects of seasonal changes and events of interest, and measuring angular dependence of ALAN sources. NITELite includes an imaging system, an inertial and positional recording on-board-computer, and an altitude control system. Preliminary results demonstrate the potential of this method for future ALAN research.

Direct assessment of the sensitivity drift of SQM sensors installed outdoors

Long-term monitoring of the evolution of the artificial night sky brightness is a key tool for developing science-informed public policies and assessing the efficacy of light pollution mitigation measures. Detecting the underlying artificial brightness trend is a challenging task, since the typical night sky brightness signal shows a large variability with characteristic time scales ranging from seconds to years. In order to effectively isolate the weak signature of the effect of interest, determining the potential long term drifts of the radiance sensing systems is crucial. If these drifts can be adequately characterized, the raw measurements could be easily corrected for them and transformed to a consistent scale. In this short note we report on the progressive darkening of the signal recorded by SQM detectors belonging to several monitoring networks, permanently installed outdoors for periods ranging from several months to several years. The sensitivity drifts were estimated by means of parallel measurements made at the beginning and at the end of the evaluation periods using reference detectors of the same kind that were little or no exposed to weathering in the intervening time. Our preliminary results suggest that SQM detectors installed outdoors steadily increase their readings at an average rate of +0.034 magSQM/arcsec2 per MWh/m2 of exposure to solar horizontal global irradiation, that for our locations translates into approximately +0.05 to +0.06 magSQM/arcsec2 per year.

Who speaks for the night?

Efforts to control artificial light at night (ALAN) through public policies began in the late 1950s, yet light pollution continues to grow at a global average rate roughly twice that of population growth. The current global ALAN regulatory regime is clearly inadequate to solve the problem, and achieving meaningful light pollution reductions requires a new approach. This paper reviews the legal status quo, introduces the “Rights of Nature” doctrine, and advances the idea of nighttime darkness as a natural characteristic of sufficient inherent value to merit legal consideration in the Rights of Nature context. It concludes with a series of recommendations for ways forward, including the recognition of the intrinsic value of dark skies in the preambulatory language of legislation, formulating new policies in anticipation of broad adoption of Rights of Nature statutes, and advancing the significance of natural nighttime darkness in case law arguments.

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.

Maps of light pollution in odd places

Advances in remote sensing have proved to be highly valuable for the light pollution research and awareness raising. Maps based on night time satellite data can be used in communication campaigns aimed to improve the public and policy awareness about the extent and effects of light pollution and to justify appropriate management actions. However, visually appealing maps are also used in other communication settings. This article reviews different uses of light pollution maps and discusses the societal implications such uses. Based on examples of light pollution maps in different communication settings not directly related to light pollution debate the review proposes that the relatively wide popularity of light pollution maps may strengthen the impressions of artificially illuminated night environment as the normal baseline for human experience. This contributes to the loss of experience of the natural darkness possibly leading to generational amnesia complicating the management of light pollution. Multiple uses of light pollution maps and other visualizations should be taken into account when campaigns and policies aimed to support sustainable lighting are planned and implemented.