YozoraAtlas

How dark is the sky in North Denmark?

Sky darkness for 6 towns and parks in North Denmark, worked out from NASA satellite images of light at night (2025). 3 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Bulbjerg (21.79, Bortle 3), the brightest Aalborg (19.00, Bortle 6). The bright core of the Milky Way never climbs clear of the horizon haze anywhere in North Denmark 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 Denmark with every place marked

Darkest skies in North Denmark

  1. BulbjergBortle 321.79
  2. Thy National ParkBortle 321.78
  3. Rebild BakkerBortle 421.30

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 Denmark

  1. AalborgBortle 619.00
  2. FrederikshavnBortle 519.54
  3. HjørringBortle 520.13

All 6 places in North Denmark

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Aalborg6Bulbjerg3Frederikshavn5Hjørring5Rebild Bakker4Thy National Park3