Light Pollution
Definition
Artificial sky brightness from human lighting that washes out faint auroras.
In plain language
City glow raises the sky's background brightness, hiding everything dimmer. A display obvious from a dark field can be invisible from a supermarket parking lot ten miles away.
The science
Skyglow scales with population density and lighting practices, scattering upward light through the atmosphere. Its impact is strongest low on the horizon โ exactly where distant auroras appear for mid-latitude observers.
Why it matters for aurora viewing
Escaping light pollution is the cheapest aurora upgrade there is: twenty minutes of driving often beats two extra points of Kp.
See this in action on tonight's data.