YozoraAtlas

How dark is the sky in North Ostrobothnia?

Sky darkness for 6 towns and parks in North Ostrobothnia, worked out from NASA satellite images of light at night (2025). 4 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Hossa National Park (21.88, Bortle 3), the brightest Oulu (17.07, Bortle 8). The bright core of the Milky Way never climbs clear of the horizon haze anywhere in North Ostrobothnia while the sky is fully dark; the rest of the band passes overhead, with the longest moonless nights from October to March.

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

NASA satellite night-lights map of North Ostrobothnia with every place marked

Darkest skies in North Ostrobothnia

  1. Hossa National ParkBortle 321.88
  2. Oulanka National ParkBortle 321.81
  3. Syöte National ParkBortle 321.80
  4. Rokua National ParkBortle 421.50

Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.

Brightest city skies in North Ostrobothnia

  1. OuluBortle 817.07
  2. RaaheBortle 818.32

All 6 places in North Ostrobothnia

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Hossa National Park3Oulanka National Park3Oulu8Raahe8Rokua National Park4Syöte National Park3