YozoraAtlas

How dark is the sky in Auvergne-Rhône-Alpes?

Sky darkness for 9 towns and parks in Auvergne-Rhône-Alpes, 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 Baronnies Provençales Regional Natural Park (21.61, Bortle 4), the brightest Lyon (18.53, Bortle 7). Milky Way season in Auvergne-Rhône-Alpes runs April to August: on moonless nights the bright core stands clear of the horizon, climbing to about 17° at its highest.

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 Auvergne-Rhône-Alpes with every place marked

Darkest skies in Auvergne-Rhône-Alpes

  1. Baronnies Provençales Regional Natural ParkBortle 421.61
  2. the VercorsBortle 421.61
  3. Vanoise National ParkBortle 421.50

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 Auvergne-Rhône-Alpes

  1. LyonBortle 718.53
  2. Saint-ÉtienneBortle 619.22
  3. Clermont-FerrandBortle 619.28
  4. GrenobleBortle 619.47
  5. ValenceBortle 519.71

All 9 places in Auvergne-Rhône-Alpes

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Baronnies Provençales Regional Natural Park4Chambéry5Clermont-Ferrand6Grenoble6Lyon7Saint-Étienne6Valence5Vanoise National Park4the Vercors4