How dark is the sky in Tartu County?
Sky darkness for 2 towns and parks in Tartu County, worked out from NASA satellite images of light at night (2025). 1 of them has skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Vooremaa Nature Park (21.06, Bortle 4), the brightest Tartu (17.78, Bortle 8). The bright core of the Milky Way never climbs clear of the horizon haze anywhere in Tartu County while the sky is fully dark; the rest of the band passes overhead, with the longest moonless nights from October to March.
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
Darkest skies in Tartu County
Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.