YozoraAtlas

How dark is the sky in Switzerland?

Sky darkness for 33 towns and parks in Switzerland, worked out from NASA satellite images of light at night (2025). 9 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Swiss National Park (21.60, Bortle 4), the brightest Geneva (19.09, Bortle 6).

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 Switzerland with every place marked

Darkest skies in Switzerland

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 Switzerland

Darkest place in each canton of Switzerland

Canton	Places	Dark places Bortle 1 to 4	Darkest place
Aargau	1 place	0 dark	Aarau19.89 · Bortle 5
Basel-City	1 place	0 dark	Basel19.15 · Bortle 6
Bern	5 places	2 dark	Gantrisch21.51 · Bortle 4
Fribourg	2 places	0 dark	Bulle20.45 · Bortle 5
Geneva	1 place	0 dark	Geneva19.09 · Bortle 6
Grisons	2 places	2 dark	Swiss National Park21.60 · Bortle 4
Lucerne	1 place	0 dark	Lucerne19.74 · Bortle 5
Neuchâtel	2 places	1 dark	La Chaux-de-Fonds21.09 · Bortle 4
Schaffhausen	1 place	0 dark	Schaffhausen20.38 · Bortle 5
Solothurn	1 place	1 dark	Thal Nature Park20.84 · Bortle 4
St. Gallen	3 places	0 dark	Rapperswil20.33 · Bortle 5
Thurgau	2 places	0 dark	Frauenfeld20.18 · Bortle 5
Ticino	2 places	0 dark	Bellinzona20.01 · Bortle 5
Valais	1 place	0 dark	Sion20.20 · Bortle 5
Vaud	4 places	3 dark	Gruyère Pays-d'Enhaut Regional Park21.37 · Bortle 4
Zug	1 place	0 dark	Zug20.10 · Bortle 5
Zurich	3 places	0 dark	Wetzikon20.34 · Bortle 5