How dark is the sky in Michigan?
Sky darkness for 45 towns and parks in Michigan, worked out from NASA satellite images of light at night (2025). 20 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Pictured Rocks National Lakeshore (21.87, Bortle 3), the brightest Detroit (16.98, 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 Michigan
- Pictured Rocks National LakeshoreBortle 321.87
- Tahquamenon Falls State ParkBortle 321.85
- Agate Falls Scenic SiteBortle 321.83
- Isle Royale National ParkBortle 321.83
- Ottawa National ForestBortle 321.83
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 Michigan
All 45 places in Michigan
Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Agate Falls Scenic Site3Ann Arbor8Battle Creek7Burt Lake State Park4Canton8Cheboygan State Park4Clinton Township8Dearborn8Detroit8Farmington Hills8Flint8Grand Rapids8Harrisville State Park4Hiawatha National Forest3Indian Lake State Park4Isle Royale National Park3Kalamazoo8Kentwood8Lake Hudson State Recreation Area5Lansing8Laughing Whitefish Falls Scenic Site3Livonia8Mackinac Island State Park4Marquette National Forest4Negwegon State Park4Novi8Ottawa National Forest3Pictured Rocks National Lakeshore3Pontiac8Rock Island State Park3Saint Clair Shores8Shelby8Silver Lake State Park4Sleeping Bear Dunes National Lakeshore4Southfield8Sterling Heights8Tahquamenon Falls State Park3Taylor8The Headlands4Thompson's Harbor State Park3Troy8Warren8Waterford7West Bloomfield Township7Wilderness State Park3