NASA astronaut Don Pettit has used his time aboard the International Space Station to document a massive shift in how our cities glow at night. His photography captures the global transition from warm, yellow sodium vapor lamps to bright, multi-colored LED lighting systems.
The 23-year transition from sodium vapor to LED
NASA astronaut Don Pettit has spent nearly 600 days in orbit capturing the visual evolution of human civilization. As reported by NASA, his images show a planet moving away from the characteristic orange haze of sodium vapor lamps toward the crisp, white, and multi-colored light of LED technology. This shift is driven largely by economics and environmental necessity, following the 1993 invention of the blue LED which made efficient white light commercially viable.
The transition represents a massive global infrastructure overhaul. For example, researchers noted that the United Kingdom saw energy savings of 30 to 40 percent when switching to LED systmes in 2012. This efficiency is why cities like Seoul, South Korea, have successfully transitioned from a bright orange glow to a clean, white grid over a 14-year period.
Miami's fading amber and the purple Vegas Sphere
Miami,Florida, servves as a primary visual case study for this technological transformation. Comparing images from 2012 to 2024, the vast yellow glow that once dominated the coastline has vanished, replaced by a spectrum of colors visible from the International Space Station. This change allows the distinct colors of the urban landscape to be distinguished from orbit in a way that was previously impossible.
Las Vegas, Nevada, has also seen its nocturnal profile evolve significantly.. While the city remains one of the brightest on Earth, it now features new LED sources such as the Vegas Sphere, which appears as a distinct purple spot in 2025 imagery. This highlights how modern LED technology can introduce entirely new colors to the traditional urban palette.
The lighting divide between Shenzhen and Hong Kong
Regional variations highlight the uneven pace of this global adoption. While Shenzhen on the Chinese mainland has embraced a multi-colored LED landscape, Hong Kong has largely retained much of its older street lighting infrastructure. Similarly, Buenos Aires, Argentina, is taking a different aesthetic approach by implementing significantly warmer LEDs, proving that the "white light" revolution is not a monolith. In Sao Paulo, Brazil, the arrival of LEDs has also introduced warmer red tones in certain areas, adding complexity to the city's nocturnal footprint.
The mystery of the world's dimming urban zones
While the transition to LEDs is widespread, the long-term impact on the night sky remains an area of investigation. According to the data shared by Pettit on X, some parts of the world are actually getting dimmer even as others brighten . While the report mentions that Mexico City has managed to maintain dark nature reserves despite widespread LED replacement, it remains unclear why certain regions are dimming or how this affects local biodiversity. Furthermore, the source does not specify if the dimming is a result of intentional light pollution mitigation or a change in energy consumption patterns.
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