How dark is the sky in Aragon?
Sky darkness for 10 towns and parks in Aragon, worked out from NASA satellite images of light at night (2025). 8 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Ordesa y Monte Perdido National Park (21.74, Bortle 3), the brightest Zaragoza (17.78, Bortle 8). Milky Way season in Aragon runs April to August: on moonless nights the bright core stands clear of the horizon, climbing to about 21° at its highest.
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 Aragon
- Ordesa y Monte Perdido National ParkBortle 321.74
- Valles Occidentales Natural ParkBortle 321.70
- Posets-Maladeta Natural ParkBortle 421.65
- Sierra y Cañones de Guara Natural ParkBortle 421.59
- Sierra de AlbarracínBortle 421.58
Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.