YozoraAtlas

How dark is the sky in New Hampshire?

Sky darkness for 7 towns and parks in New Hampshire, worked out from NASA satellite images of light at night (2025). 5 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Mount Washington State Park (21.57, Bortle 4), the brightest Manchester (18.27, Bortle 8).

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 New Hampshire with every place marked

Darkest skies in New Hampshire

  1. Mount Washington State ParkBortle 421.57
  2. White Mountain National ForestBortle 421.55
  3. Franconia Notch State ParkBortle 421.48
  4. Cardigan Mountain State ParkBortle 421.34
  5. Rhododendron State ParkBortle 420.90

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 New Hampshire

  1. ManchesterBortle 818.27
  2. NashuaBortle 718.57

All 7 places in New Hampshire

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Cardigan Mountain State Park4Franconia Notch State Park4Manchester8Mount Washington State Park4Nashua7Rhododendron State Park4White Mountain National Forest4