Light Pollution Converter
Convert between different light pollution measurement units including Bortle scale, magnitude per square arcsecond, and more
Light Pollution Converter
Conversion Result:
Class 2: Typical truly dark site
Common Scenarios
Impact on Astronomy
Excellent for all types of astronomy. Milky Way shows intricate detail. Zodiacal light clearly visible. Good for astrophotography without filters.
About Light Pollution Measurement:
Understanding the Units:
- Magnitude per Square Arcsecond (mag/arcsec²): Astronomical measurement of sky brightness. Higher values (21-22) indicate darker skies.
- Bortle Scale: 9-point scale (1-9) with 1 being the darkest and 9 being the brightest/most light-polluted.
- NELM: Naked Eye Limiting Magnitude - the faintest stars visible. Higher values (6-7+) indicate darker skies.
- Nanolambert (nL): Photometric unit of luminance. Higher values indicate brighter skies.
- SQM: Sky Quality Meter reading - a direct measure in mag/arcsec².
Effects of Light Pollution:
- Astronomy: Washes out stars and deep sky objects, reduces contrast.
- Wildlife: Disrupts nocturnal animals, affects bird migration patterns.
- Human Health: Can disrupt circadian rhythms and affect melatonin production.
- Energy: Wasted light means wasted energy and increased carbon emissions.
- Cultural: Many people have never seen a truly dark sky or the Milky Way.
Bortle Scale Reference
| Class | Description | Mag/arcsec² |
|---|---|---|
| 1 | Excellent dark-sky site | >21.7 |
| 2 | Typical truly dark site | 21.5-21.7 |
| 3 | Rural sky | 21.3-21.5 |
| 4 | Rural/suburban transition | 20.8-21.3 |
| 5 | Suburban sky | 19.5-20.8 |
| 6 | Bright suburban sky | 18.5-19.5 |
| 7 | Suburban/urban transition | 18.0-18.5 |
| 8 | City sky | 17.0-18.0 |
| 9 | Inner-city sky | <17.0 |
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Light Pollution Visualization
Visible Features by Sky Quality
Dark Site (>21 mag/arcsec²):
- Milky Way clearly structured
- Zodiacal light visible
- Faint objects like M33 visible
- Stars visible to magnitude 6.5+
Rural Site (19-21 mag/arcsec²):
- Milky Way visible but with less detail
- Light domes visible at horizon
- Most Messier objects visible
- Stars visible to magnitude 5.5-6.5
Suburban Site (18-19 mag/arcsec²):
- Milky Way faint or only at zenith
- Sky glow dominates horizons
- Brighter Messier objects visible
- Stars visible to magnitude 4.5-5.5
Urban Site (<18 mag/arcsec²):
- Milky Way not visible
- Sky appears grayish/orange
- Only planets and brightest stars
- Stars visible to magnitude <4.5
Mobile tip: Swipe left or right on the unit dropdown to quickly change units, or use the arrow buttons
About the Light Pollution Converter
Convert between different light pollution measurement units including Bortle scale, magnitude per square arcsecond, and more All conversions run instantly in your browser and nothing you enter is sent to a server.
Common Conversion Formulas
| From | To | Formula |
|---|---|---|
| Bortle Scale | Limiting Magnitude | Class 1: 7.6-8.0, Class 9: < 4.0 |
| Magnitudes per Square Arcsecond (mpsas) | Bortle Scale | 22.0+ mpsas: Class 1, < 18.0 mpsas: Class 8-9 |
| Magnitudes per Square Arcsecond (mpsas) | Nanolamberts (nL) | nL ≈ 34.08 × 10^(20.7233 - mpsas)/2.5 |