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When to Use Bortle Scale Light Pollution 3D Explorer

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Open the Bortle Scale Light Pollution 3D Explorer when you need to see what a light-pollution class actually hides, or decide whether a planned stargazing site is dark enough for what you want to observe.


A light-pollution lesson

A lesson starts when you drag the class slider from 1 to 9 and watch the star count and Milky Way visibility change, then jump between the excellent-dark-site and city-sky presets to see the two extremes side by side.


Sessions this explorer does not fit

Sessions this page does not fit are learning the magnitude NUMBER SYSTEM itself - use the Stellar Magnitude Explorer for that - or getting a real, repeatable brightness reading for your own backyard - use an actual Sky Quality Meter or a real-time light-pollution map for that. Walk the controls in the step-by-step guide.

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Reviewed by the Free Tool Online editorial team · Tested in the current versions of Chrome, Firefox, Safari, and Edge before publishing. No account is needed to use any tool. Report a bug - we triage within 72 hours. · Last refreshed April 2026.

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