Light pollution map of Europe.
- Grey areas: Pristine sky
- Blue/green/ochre areas: Some light pollution, but Milky Way may still be visible
- Yellow areas: Winter Milky Way not visible, but summer Milky Way may be visible
- Orange areas: Milky Way not visible
- Red: Equivalent brightness to nautical twilight, regime of mesopic vision entered (ie where eyes start to use cones as well as rods to view light)
The Ruhrpott and Germany’s largest cities are clearly visible on this map. That said, 1/3 of Germany still is nature/countryside.