25/11/2025
Swipe ➡️ to watch the stars disappear.
This is the Bortle Scale, the standard way to measure the quality of the night sky. In Luxembourg, we often live in zones 5 to 7, but true darkness is still out there if you know where to look.
Here is your guide to identifying the sky above you:
🌿 THE DARK SKIES
Class 1 (Excellent Dark Sky): The "Ancient Sky." The Milky Way is so bright it casts shadows on the ground.
Class 2 (Typical Dark Sky): The Milky Way is highly structured. Clouds look like black holes against the stars.
Class 3 (Rural Sky): The Milky Way is complex, but light domes from distant cities appear on the horizon.
🏡 THE TRANSITION
Class 4 (Rural/Suburban): The Milky Way is still visible, but lacks detail. The surroundings are clearly visible.
Class 5 (Suburban Sky): The Milky Way is very faint or invisible near the horizon. Clouds are brighter than the sky.
Class 6 (Bright Suburban): The "average" sky for many. No Milky Way. The sky glows a grayish-white.
🏢 THE CITY LIGHTS
Class 7 (Suburban/Urban): The entire sky is a vague, grayish glow. Only bright stars remain.
Class 8 (City Sky): The sky is orange or white. You can read a newspaper outside at night.
Class 9 (Inner City): Only the Moon, planets, and a few bright stars struggle through the glare.
🛑 THE GOOD NEWS (Swipe to the end)
As we share on the last slide, unlike plastic or chemical pollution, light pollution is 100% reversible at the speed of light.
We just need to change how we use it.
Where does your home fall on this list? Tell us in the comments! 👇
