YozoraAtlas

How dark is the sky in Utrecht?

Sky darkness for 4 towns and parks in Utrecht, 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 Utrechtse Heuvelrug National Park (20.19, Bortle 5), the brightest Utrecht (18.94, Bortle 7). The bright core of the Milky Way never climbs clear of the horizon haze anywhere in Utrecht 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 Utrecht with every place marked

Darkest skies in Utrecht

  1. Utrechtse Heuvelrug National ParkBortle 520.19
  2. VeenendaalBortle 619.42
  3. AmersfoortBortle 619.29

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 Utrecht

  1. UtrechtBortle 718.94

All 4 places in Utrecht

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Amersfoort6Utrecht7Utrechtse Heuvelrug National Park5Veenendaal6