YozoraAtlas

How dark is the sky in Flanders?

Sky darkness for 16 towns and parks in Flanders, worked out from NASA satellite images of light at night (2025). None of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Bosland National Park (20.14, Bortle 5), the brightest Antwerp (18.44, Bortle 7). The bright core of the Milky Way never climbs clear of the horizon haze anywhere in Flanders while the sky is fully dark; the rest of the band passes overhead, with the longest moonless nights from September 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 Flanders with every place marked

Darkest skies in Flanders

  1. Bosland National ParkBortle 520.14
  2. Hoge Kempen National ParkBortle 519.82
  3. Scheldt Valley National ParkBortle 519.73

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 Flanders

  1. AntwerpBortle 718.44
  2. GentBortle 718.87
  3. MechelenBortle 618.97
  4. KortrijkBortle 619.11
  5. LeuvenBortle 619.16

All 16 places in Flanders

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Aalst6Antwerp7Bosland National Park5Brugge6Forests of Brabant National Park5Genk6Gent7Hasselt6Hoge Kempen National Park5Kortrijk6Leuven6Mechelen6Ostend6Roeselare6Scheldt Valley National Park5Sint-Niklaas6