Author: Tomáš Klouček
Darkness, once an integral part of life on Earth, is now rapidly vanishing. The spread of artificial lighting—often excessive, misdirected, or poorly regulated—has created a form of pollution that is both overlooked and far-reaching. Known as light pollution, it disrupts ecosystems, affects human health, and fundamentally alters our relationship with the night sky. Yet unlike many environmental challenges, light pollution is reversible. Solutions are within reach: smarter lighting design, policy interventions, and data-informed planning. But first, we must understand the problem—scientifically, spatially, and temporally.
That is the goal of our ongoing research project focused on mapping and analyzing light pollution in Brno, conducted through a collaboration between the Czech University of Life Sciences Prague (CZU) and the CzechGlobe research institute. On March 27, 2025, an extensive data collection campaign was carried out using airborne, satellite, and field-based sensors. This research is not only technically innovative—it is also a call to action. Preserving natural darkness benefits not only wildlife and astronomical research, but also human health and societal well-being. By better understanding where and how we light our cities, we gain the tools to illuminate more wisely—and perhaps, to bring the stars back into view.
A key asset in our research is the targeted nighttime data captured by the Flying Laboratory of Imaging Systems (FLIS), which conducted overflights of Brno using both visible and thermal spectral bands. These airborne datasets reveal fine-grained differences in lighting patterns between urban zones, infrastructure types, and adjacent rural areas. Complementing the airborne data, we also leverage rare nighttime imagery from the Landsat satellite program. Although Landsat was not originally designed for nighttime observation, under specific thermal and illumination conditions it occasionally captures usable scenes. These offer valuable radiometric data for spatial analysis of urban lighting intensity and distribution.
To validate and enrich our remote sensing data, an extensive field campaign was conducted in and around Brno. These ground-based measurements served two main purposes: to provide ground-truth reference data for the satellite and airborne imagery, and to explore possible links between artificial lighting and urban microclimate conditions. One mobile team, led by CZU master’s student Šimon Kavan, traversed a 117-kilometer route with a Sky Quality Meter (SQM) mounted on a custom-designed rooftop rig, collecting continuous data on sky brightness across a diverse range of urban, suburban, and rural environments. Simultaneously, CzechGlobe researchers Olga Brovkina and Daniel Kopkáně conducted pedestrian temperature surveys throughout the city center, recording surface and ambient air temperatures using portable loggers and thermometers.
The combined datasets will allow us to quantify differences in light pollution between urban cores and outlying districts, identify hotspots of excessive brightness, and evaluate the extent to which artificial lighting may exacerbate the urban heat island effect. The project will also include classification of lighting types by intensity and spectrum, analysis of light leakage, and spatial correlations with land use and population density. These findings will form the basis of the following analysis.
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