Light Pollution & Sky Darkness
Understand your sky quality using the Bortle Dark-Sky Scale
Light Pollution Zone
Artificial light vs natural sky
0 under 0.01×22.00-21.99
1 0.01-0.11×21.99-21.89
2 0.11-0.33×21.89-21.69
3 0.33-1×21.69-21.25
4 1-3×21.25-20.49
5 3-9×20.49-19.50
6 9-27×19.50-18.38
7 over 27×<18.38
Right column: mag/arcsec² overhead
Tap the map for a reading
Light pollution data: David Lorenz Light Pollution Atlas using NASA VIIRS satellite imagery. Base map: Esri, HERE, Garmin, OpenStreetMap contributors.
The Bortle Dark-Sky Scale
John Bortle's nine-level scale rates the darkness of an observing site, from pristine dark skies to inner-city glow.
You judge Bortle by eye, across the whole sky, including glow from towns on the horizon. The map above measures only the sky straight overhead, so it gives a light pollution zone, not a Bortle class.
What Can I See From My Sky?
Select your Bortle class to see what objects and phenomena are visible.