🌌 Night Sky Brightness Calculator
Convert night sky brightness between magnitudes per square arcsecond and linear luminance, a standard measure used in astronomy and light pollution studies.
What this measures
Night sky brightness describes how bright the night sky glows, usually due to a mix of natural airglow, starlight, and artificial light pollution. It is commonly reported in magnitudes per square arcsecond, a logarithmic astronomical brightness scale.
The formula
This calculator uses the standard conversion (used by sky quality meters and light-pollution researchers) from magnitude per square arcsecond to linear luminance in nanolamberts: nL = 34.08 × e(20.7233 – 0.92104m), where m is the sky brightness in mag/arcsec². A darker sky corresponds to a higher magnitude number and a lower nanolambert value.
This is a widely used approximate conversion for general astronomy and light-pollution reference; exact readings depend on instrument calibration.