How dark is the sky in Kentucky?
Sky darkness for 14 towns and parks in Kentucky, 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 Land Between the Lakes National Recreation Area (21.08, Bortle 4), the brightest Louisville (17.44, 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
Darkest skies in Kentucky
- Land Between the Lakes National Recreation AreaBortle 421.08
- Natural Bridge State Resort ParkBortle 420.84
- Cumberland Falls State Resort ParkBortle 420.83
- Carter Caves State Resort ParkBortle 420.79
- Mammoth Cave National ParkBortle 420.70
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 Kentucky
All 14 places in Kentucky
Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Bowling Green8Camp Nelson National Monument5Carter Caves State Resort Park4Cumberland Falls State Resort Park4Daniel Boone National Forest4Land Between the Lakes National Recreation Area4Lexington8Lexington-Fayette8Louisville8Mammoth Cave National Park4Meads6Mill Springs Battlefield National Monument5Natural Bridge State Resort Park4Owensboro8