A citizen science approach for monitoring night sky brightness is reported in the journal Scientific Reports this week. The research suggests that aggregate data from naked eye observations could eventually be used to study changes in levels of skyglow, a form of light pollution caused by the scattering of artificial light in the atmosphere.

Skyglow is a global environmental concern because of its known and potential ecological effects. GLOBE at Night is a citizen science project related to light pollution, which has been running since 2006. The project asks citizen scientists to go outside at least one hour after sunset and compare their view of a constellation to that shown in a series of star charts, which differ only in the brightness of the stars shown.

Christopher Kyba and colleagues evaluate the systemic uncertainty associated with individual naked eye GLOBE at Night sky luminance estimates. They show that aggregate data from naked eye observations of GLOBE at Night participants are strongly correlated with the artificial skyglow level in the area. The authors go on to test skyglow estimates from the First World Atlas of Artificial Night Sky Brightness using a subset of the GLOBE at Night data. Although the results indicate that the Atlas tends to overestimate sky brightness in the centre of large cities, its predictions for the Milky Way are accurate.

The uncertainty associated with the naked eye data from a single site means that observing trends at a single location could take decades, but the full GLOBE at Night dataset could become an increasingly useful tool in light at night research, the authors suggest.