BORTLE CLASS 7 / SKY KEY
Suburban / urban transition
The Milky Way is generally gone and the night shifts toward brighter stars, planets, double stars and the Moon.
7
HOW TO READ IT
One number is a sketch of the sky, not the whole night.
A Bortle class describes what the sky looks like under particular conditions. Walk across a large park, turn toward a town, add snow or smoke, and the view can change. Use the number to compare darkness quickly, then read the stop page for the horizon, headlights, access and everything else that decides whether the place actually works.