How dark is the sky in Finland?
Sky darkness for 86 towns and parks in Finland, worked out from NASA satellite images of light at night (2025). 32 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Lemmenjoki National Park (21.88, Bortle 3), the brightest Rovaniemi (17.07, 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 Finland
- Lemmenjoki National ParkLapland · Bortle 321.88
- Hossa National ParkNorth Ostrobothnia · Bortle 321.88
- Petkeljärvi National ParkNorth Karelia · Bortle 321.86
- Patvinsuo National ParkNorth Karelia · Bortle 321.83
- Pallas-Yllästunturi National ParkLapland · Bortle 321.81
Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.