LIGHT POLLUTION SURVEY AND ANALYSIS OF WINONA, MN

The night sky is a natural resource which has become impaired in modern times due to light pollution. Caused by excessively bright or poorly directed lighting, light pollution results in disrupted nocturnal animal behavior, high costs from wasted energy, and reduced nighttime observational astronomy quality. The Winona State University (WSU) Geoscience Department operates and maintains an on-campus observatory within Winona, MN. Nearby sources of light pollution interfere with the telescope and night sky viewing at the observatory. The observatory was installed in the 1970s before much of the nearby lighting sources were installed. In order to plan for the future of observational astronomy at WSU, an understanding of the intensity and distribution of light pollution on campus and within the city is required.

Winona is an ideal city for surveying light pollution due to its population, area, and relative isolation from nearby bright cities. I conducted a ground survey within and around the city and the WSU campus on clear moonless nights using night sky quality meters, ambient light meters, and GPS equipment. I also conducted a nighttime aerial photography mission to create a map-view composite photograph of Winona to detect lighting sources from the air. This data was mapped using ArcGIS and analyzed to determine source, intensity, and distribution of light pollution. Although analysis shows light pollution levels generally decrease with distance from the city, within the city there is seen a relationship between light pollution contribution and zoning type. This relationship indicates higher light pollution levels within and adjacent to commercial zoning, with decreasing light pollution values in industrial, residential and rural zoning. This relationship is consistent with observed lighting types and intensities. The WSU Observatory is within a localized zone of increased light pollution levels due to campus lighting practices and proximity to the downtown commercial district. This information can be used to plan for protection of the observational and educational quality of the WSU Observatory by adopting better lighting practices and predicting future light pollution levels, possibly requiring relocation of the observatory to darker skies.