Using satellites, scientists are starting to better understand the specific sources of urban light pollution.
Since the invention and spread of artificial light, few locations on Earth appear entirely dark after sundown anymore. Even in a place like Tucson, Arizona—located near premiere “dark-sky” locations for astronomers and stargazers—the night sky is illuminated to a certain extent by artificial light sources. Using satellites, scientists are starting to better understand the specific sources of this light pollution.
In a 2020 study led by Christopher Kyba of the German Research Center for Geosciences, scientists conducted an experiment with Tucson’s lights. They brightened then dimmed some streetlights for a few nights and used satellite images to observe changes in Tucson’s radiance. The results are not what you might expect.
A typical night for Tucson is captured in this image, acquired around 2:30 a.m. local time on April 24, 2021, by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NOAA-NASA Suomi NPP satellite. The VIIRS sensor has a day-night band (DNB) that detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe signals such as city lights, wildfires, and reflected moonlight.
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Image via NASA Earth Observatory
