CUPOLA / EARTH SCIENCE
The lights of our night-side planet.
See how Earth-observing satellites reveal patterns of artificial light, and why beautiful nighttime mosaics should never be confused with instantaneous photographs.
What VIIRS measures
The Visible Infrared Imaging Radiometer Suite detects nighttime radiance. Products differ in processing, availability and how observations are combined.
Daily does not mean every pixel is from tonight
A daily product may include clouds, gaps, resampling or temporal gap-filling. An attractive illuminated city map can combine observations from different dates.
Why CUPOLA uses a historical fallback
When validated current imagery is missing or too incomplete, a historical Black Marble composite can preserve a readable Earth-at-night view. That historical origin must remain disclosed.
Interpreting the lights carefully
Visible radiance depends on lighting, observation conditions and processing. It is not a direct count of city population or electrical consumption.