Exceptional darkness
Rich Milky Way detail, zodiacal band and extremely faint naked-eye objects.
Find your darker sky
Bortle field guide Light Pollution Map
UK & Ireland · tonight
Find clearer skies
Sampled areas · access and driving routes not verified.
Find nearby areas with a useful window of astronomical darkness.
How this comparison works
Samples up to three land points in each of eight directions, choosing the darkest available atlas estimate in each direction. It compares up to eight areas with your starting point—not every location in the radius.
Windows use astronomical darkness and complete hourly cloud forecasts. The cloud limit must be met throughout the window. Times are planning estimates, not minute-by-minute predictions. Moon-down uses a level horizon.
Sampled areas are not verified observing sites. Check roads, access, terrain, local lights and current weather. Distances are straight-line, not driving distances. The setup allowance is yours, not a route estimate.
Land and major-lake exclusions use Natural Earth; small waterways and shoreline detail may be missing. Brightness uses the 2025 atlas, not a live measurement or an assigned Bortle class.
Modelled skyglow · 2025
Atlas colour key
Sky brightness zones, not Bortle classes. The ring marks your selected site.Atlas: David Lorenz · 2025 / EOG VIIRS65°S–75°N · approximately 1 km north–south samplingColour key & method ↗
What will the sky look like?
1 · darkest 9 · brightestThe Bortle field guide
Bortle rates the whole sky by eye, not just brightness overhead. Use the map to compare sites, then assess your sky on a clear, moonless night.
Truly dark
Strong Milky Way structure; clouds stand out as dark gaps.
Rural
Milky Way detail remains strong; some glow sits on the horizon.
Rural–suburban
Visible light domes; the Milky Way loses its finer structure.
Suburban
Milky Way washed out overhead and weak near the horizon.
Bright suburban
Only a hint of the Milky Way near overhead; the horizon glows.
Suburban–urban
Milky Way largely lost; a grey background across the sky.
City
Bright sky; some familiar constellation stars disappear.
Inner city
Many constellation stars lost; Moon and planets remain rewarding.
Based on John E. Bortle’s observing scale. Why the atlas doesn’t assign a Bortle number ↗
About these estimates
The estimates do not include tonight’s Moon, cloud, transparency, nearby lamps or new developments. Sky brightness adds a reference natural background of 22 mag/arcsec². Zooming in does not increase the underlying data resolution. Dark areas are not recommendations for access or parking.
Map tiles and small regional atlas files load directly from their providers. Location searches use our shared geocoder. Your GPS is requested only when you choose Locate me, and a link includes your pin only when you choose to share it.