Galway has been included in an international study on light pollution in urban areas.
The citizen science project, led from Germany, reveals that streetlights are far from the only source of light pollution affecting the night sky.
The study, published in Nature cities, challenges the common assumption that streetlights are the main contributor to urban light pollution.
It examined over 230 thousand individual light sources during more than 3,800 night-time surveys across Europe - including in Galway and Mayo.
The local effort was led by University of Galway researcher, Georgia MacMillan, who also looked at the university campus.
Overall, the study found that residential, commercial, and other non-street light sources play a much more significant role in brightening our night skies than commonly thought.
It notes that unlike streetlights, much of these types of lighting remain on well after midnight unnecessarily.
