YozoraAtlas

How dark is the sky in Uusimaa?

Sky darkness for 17 towns and parks in Uusimaa, worked out from NASA satellite images of light at night (2025). 1 of them has skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Liesjärvi National Park (21.23, Bortle 4), the brightest Helsinki (17.26, Bortle 8). The bright core of the Milky Way never climbs clear of the horizon haze anywhere in Uusimaa 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 Uusimaa with every place marked

Darkest skies in Uusimaa

  1. Liesjärvi National ParkBortle 421.23

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 Uusimaa

  1. HelsinkiBortle 817.26
  2. VantaaBortle 817.69
  3. EspooBortle 818.18
  4. JärvenpääBortle 818.37
  5. TuusulaBortle 718.49

All 17 places in Uusimaa

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Espoo8Helsinki8Hyvinkää7Järvenpää8Kirkkonummi7Klaukkala7Liesjärvi National Park4Lohja6Mäntsälä6Nurmijärvi6Nuuksio National Park5Porvoo7Raseborg5Sipoo6Tuusula7Vantaa8Vihti5