How dark is the sky in Spain?
Sky darkness for 214 towns and parks in Spain, worked out from NASA satellite images of light at night (2025). 93 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Caldera de Taburiente National Park (21.83, Bortle 3), the brightest Leganés (17.65, Bortle 8).
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
Darkest skies in Spain
- Caldera de Taburiente National ParkCanary Islands · Bortle 321.83
- La PalmaCanary Islands · Bortle 321.83
- Cumbre Vieja Natural ParkCanary Islands · Bortle 321.82
- Ordesa y Monte Perdido National ParkAragon · Bortle 321.74
- Valles Occidentales Natural ParkAragon · Bortle 321.70
Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.