What is a Bortle Scale?

The Bortle Scale is a nine-level system used to measure the darkness of the night sky, from Class 1 (pristine, natural skies) to Class 9 (inner-city skies). In astrotourism, it helps travellers understand what celestial sights they can expect at a destination. Lower Bortle classes mean darker skies, better visibility of the Milky Way, faint stars, nebulae, and meteor showers, and more immersive stargazing experiences. Accommodations and parks often reference their Bortle rating to attract stargazers, astrophotographers, and nature enthusiasts seeking authentic dark-sky experiences away from light pollution.

What to expect at a Dark Sky Destinations partner location!