How dark is the sky in Missouri?
Sky darkness for 25 towns and parks in Missouri, worked out from NASA satellite images of light at night (2025). 11 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Grand Gulf State Park (21.44, Bortle 4), the brightest Kansas City (17.02, 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 Missouri
- Grand Gulf State ParkBortle 421.44
- Johnson's Shut-Ins State ParkBortle 421.37
- Mark Twain Birthplace State Historic SiteBortle 421.36
- Mark Twain State ParkBortle 421.36
- Taum Sauk Mountain State ParkBortle 421.30
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 Missouri
All 25 places in Missouri
Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Bennett Spring State Park4Big Oak Tree State Park4Blue Springs8Columbia8Florissant8Gateway Arch National Park8George Washington Carver National Monument5Grand Gulf State Park4Ha Ha Tonka State Park4Hawn State Park4Independence8Johnson's Shut-Ins State Park4Joplin8Kansas City8Lee's Summit8Mark Twain Birthplace State Historic Site4Mark Twain National Forest4Mark Twain State Park4O'Fallon8Onondaga Cave State Park4Saint Charles8Saint Joseph7Springfield8St. Louis8Taum Sauk Mountain State Park4