YozoraAtlas

How dark is the sky in Greater Poland?

Sky darkness for 14 towns and parks in Greater Poland, worked out from NASA satellite images of light at night (2025). 6 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Warta Landscape Park (20.99, Bortle 4), the brightest Poznań (18.18, Bortle 8). The bright core of the Milky Way never climbs clear of the horizon haze anywhere in Greater Poland 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

All 14 places in Greater Poland

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Gniezno5Kalisz6Konin5Lednica Landscape Park4Leszno6Ostrów Wielkopolski6Piła6Powidz Landscape Park4Poznań8Przemęt Landscape Park4Puszcza Zielonka Landscape Park4Sieraków Landscape Park4Warta Landscape Park4Wielkopolska National Park5