Dark Skies

Light pollution, the Bortle scale, site scouting, and dark-sky travel.

Dark Skies · Jul 13, 2026 · 9 min

The Bortle Scale, Explained: How Dark Is Your Sky?

John Bortle's nine-class scale turns a vague impression into a number you can read and record. Here is what each class looks like overhead, from a pristine Class 1 to an inner-city Class 9, and how to reach darker skies within a night's drive.

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