Can we illuminate our cities and (still) see the stars?

TL;DR

This paper explores how urban lighting policies can be optimized to allow city residents to see stars again, emphasizing the importance of controlling light emissions and glare to recover dark skies in metropolitan areas.

Contribution

It demonstrates that with proper light emission levels and glare management, dark skies are achievable even in large city centers, informing science-based urban lighting decisions.

Findings

Dark skies are possible in city centers with controlled light emissions.

Reducing glare enhances visibility of stars in urban environments.

Policy measures can enable star visibility in cities.

Abstract

Could we enjoy starry skies in our cities again? Arguably yes. The actual number of visible stars will depend, among other factors, on the spatial density of the overall city light emissions. In this paper it is shown that reasonably dark skies could be achieved in urban settings, even at the center of large metropolitan areas, if the light emissions are kept within admissible levels and direct glare from the light sources is avoided. These results may support the adoption of science-informed, democratic public decisions on the use of light in our municipalities, with the goal of recovering the possibility of contemplating the night sky everywhere in our planet.