Light as data
Satellite sensors record night-time brightness. Geographers use it as a proxy for population density, electrification and economic activity.
Reading the patterns
Ribbon-shaped glow follows roads and rivers. Dark patches inside bright regions can mean parkland, mountains, or communities without reliable power.
The limits of the method
Bright is not the same as rich. Industrial flaring, tourism and street-lighting policy all distort the picture, so light data is compared with census figures.