YozoraAtlas

How dark is the sky in Utah?

Sky darkness for 50 towns and parks in Utah, worked out from NASA satellite images of light at night (2025). 35 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Bears Ears National Monument (21.91, Bortle 2), the brightest Salt Lake City (17.20, Bortle 8). Milky Way season in Utah runs March to September: on moonless nights the bright core stands clear of the horizon, climbing to about 24° at its highest.

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 50 places in Utah

Amber names are parks and certified dark-sky places. The figure is the Bortle class: 1 darkest, 9 city center.
Antelope Island State Park5Arches National Park3Ashley National Forest4Bear Lake State Park4Bears Ears National Monument2Beaver Dam Wash National Conservation Area4Bryce Canyon National Park3Cache National Forest4Canyonlands National Park2Capitol Reef National Park2Cedar Breaks National Monument4Coral Pink Sand Dunes State Park4Dead Horse Point State Park3Dixie National Forest2East Canyon State Park5Escalante Petrified Forest State Park3Fishlake National Forest4Flaming Gorge National Recreation Area4Fred Hayes State Park at Starvation4Goblin Valley State Park2Goosenecks State Park3Grand Staircase-Escalante National Monument2Hovenweep National Monument3John Wesley Powell National Conservation Area3Jurassic National Monument3Kodachrome Basin State Park3Layton8Lehi8Logan7Manti-La Sal National Forest4Millcreek8Millsite State Park4Natural Bridges National Monument2Ogden8Palisade State Park4Provo8Rainbow Bridge National Monument3Red Cliffs National Conservation Area5Rockport State Park4Saint George7Salt Lake City8Sandy8Steinaker State Park4Torrey4Wasatch-Cache National Forest4Weber County North Fork Park5West Jordan8West Valley City8Yuba State Park4Zion National Park4