YozoraAtlas

How dark is the sky in Catalonia?

Sky darkness for 25 towns and parks in Catalonia, worked out from NASA satellite images of light at night (2025). 9 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Aigüestortes i Estany de Sant Maurici National Park (21.67, Bortle 4), the brightest Barcelona (17.81, Bortle 8). Milky Way season in Catalonia runs April to August: on moonless nights the bright core stands clear of the horizon, climbing to about 20° at its highest.

19 Bortle class, 1 pristine to 9 city center park or dark-sky place city

Numbers like 21.95 or 16.97 are the brightness of the sky overhead on a clear, moonless night, in mag/arcsec². The scale runs backwards: a lower number means a brighter sky, from about 22 for a natural sky to about 17 in a city center.
How the readings are made

All 25 places in Catalonia

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Aigüestortes i Estany de Sant Maurici National Park4Albanyà4Badalona8Barcelona8Cadí-Moixeró Natural Park4Castelldefels7Delta de l'Ebre Natural Park4Els Ports Natural Park4Girona7Granollers7High Pyrenees Natural Park4Lleida6Manresa6Mataró7Mollet del Vallès7Montsec4Reus7Sabadell7Sant Boi de Llobregat8Sant Cugat del Vallès7Serra de Montsant Natural Park4Tarragona8Terrassa7Vilanova i la Geltrú7Zona Volcànica de la Garrotxa Natural Park4