I have spent 23 years documenting the global LED transition of city lighting from space.

Across my 4 missions to the ISS, I have photographed every major city on Earth, building a data set of the gradual replacement of sodium vapor lighting with LEDs.

The warmer, yellow-orange… https://t.co/gNNiEULpkr pic.twitter.com/ChFbj8Jtgs

— Don Pettit (@astro_Pettit) September 7, 2026