Light pollution: Assessment of sky glow on two dark sky regions of Portugal

Tourists’ Preferences for Stargazing Land Resources

Stargazing tourism is an expanding market niche that requires the development of territorial resources for its implementation and attraction. This paper’s objective is to investigate the preferences and willingness to pay of tourists for the development of strategic land resources for stargazing tourism activities. The field work was conducted on the island of La Palma (Canary Islands), which is promoting the territorial development of infrastructures for stargazing tourism. A random sample of 734 tourists were interviewed in person on-site in December 2019 following the methodology discrete choice experiments that enabled an estimation of tourists’ preferences and willingness to pay for the implementation of key land resources for stargazing. The data are modeled using a latent class model that allows for the consideration of heterogeneous preferences. The results show that there are three groups of tourists with different preferences for land resources of stargazing observation. These segments are respectively related to the interests in culture, active, and astronomic tourism. Those tourists in the active stargazing segment share the largest proportion of the market and favor the implementation of facilities that allow the combination of active tourism with stargazing. The results are useful for land product development and territorial strategies aimed at positioning destinations in the identified demand niches of stargazing tourism.

Ecological Impact of Artificial Light at Night: Effective Strategies and Measures to Deal with Protected Species and Habitats

When conserving or protecting rare or endangered species, current general guidelines for reducing light pollution might not suffice to ensure long-term threatened species’ survival. Many protected areas are exposed to artificial light at levels with the potential to induce ecological impacts with unknown implications for the ecosystems they are designated to protect. Consequently, it is recommended that precautionary methods for the avoidance and mitigation of light pollution in protected areas be integrated into their management plans. This paper’s aims are to present an overview of best practices in precautionary methods to avoid and mitigate light pollution in protected areas and to identify and discuss what ecosystems should be considered light-sensitive and how to prioritise species and habitats that need protection from artificial light, including examples of legislation covering ecological light pollution in the European Union and in Sweden. The important aspects to include when considering light pollution at a landscape level are listed, and a proposal for prioritisation among species and habitats is suggested. Sensitive and conservation areas and important habitats for particularly vulnerable species could be prioritised for measures to minimise artificial lighting’s negative effects on biodiversity. This may be done by classifying protected natural environments into different zones and applying more constrained principles to limit lighting. The light pollution sensitivity of various environments and ecosystems suggests that different mitigation strategies and adaptations should be used depending on landscape characteristics, species sensitivity and other factors that may determine whether artificial light may be detrimental. Issues of the currently used measurement methods for artificial light at night are reviewed. We also propose and discuss the principles and benefits of using standardized measurement methods and appropriate instrumentation for field measurements of artificial light concerning the environmental impact of light pollution.

Monitoring Long-Term Trends in the Anthropogenic Night Sky Brightness

Monitoring long-term trends in the evolution of the anthropogenic night sky brightness is a demanding task due to the high dynamic range of the artificial and natural light emissions and the high variability of the atmospheric conditions that determine the amount of light scattered in the direction of the observer. In this paper, we analyze the use of a statistical indicator, the mFWHM, to assess the night sky brightness changes over periods of time larger than one year. The mFWHM is formally defined as the average value of the recorded magnitudes contained within the full width at half-maximum region of the histogram peak corresponding to the scattering of artificial light under clear skies in the conditions of a moonless astronomical night (sun below −18°, and moon below −5°). We apply this indicator to the measurements acquired by the 14 SQM detectors of the Galician Night Sky Brightness Monitoring Network during the period 2015–2018. Overall, the available data suggest that the zenithal readings in the Sky Quality Meter (SQM) device-specific photometric band tended to increase during this period of time at an average rate of +0.09 magSQM/arcsec2 per year.