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Bortle Scale Light Pollution 3D Explorer vs alternatives
The Bortle Scale Light Pollution 3D Explorer shows what every one of the 9 published classes actually looks like in one interactive scene - a Sky Quality Meter wins for a real repeatable number at your own site; a light-pollution atlas wins for a real map of your actual location.
| Option | Strength | Access | Trade-off |
|---|---|---|---|
| Bortle Scale Light Pollution 3D (this page) | All 9 classes shown side by side with a live star count and Milky Way fade | Free, in browser | Teaching illustration; not a real reading of any specific location |
| Sky Quality Meter (SQM) | Real, repeatable brightness reading in magnitudes per square arcsecond | Requires buying a physical meter | Only measures your one location; no visual teaching scene |
| Online light-pollution atlases (e.g. World Atlas of Artificial Night Sky Brightness) | Real satellite-derived map of your actual location | Free, online | Shows a modeled brightness value, not what a human eye actually sees at each class |
Key published figures
| Figure | Value |
|---|---|
| Class 1 limiting magnitude | 7.6-8.0 |
| Class 5 limiting magnitude | 5.6-6.0 |
| Class 9 limiting magnitude | 4.0 or less |
Start with the step-by-step guide or when to use. Open the Bortle Scale Light Pollution 3D Explorer.
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