A groundbreaking study using daily satellite imagery has uncovered surprising patterns in how artificial lighting changes across our planet after dark, revealing a complex picture that goes far beyond simple urban growth.
Scientists analyzing over one million daily satellite images found that global nighttime illumination rose 16% between 2014 and 2022, but this increase wasn’t uniform across regions. Instead, researchers discovered a complex mix of brightening and dimming driven by vastly different factors worldwide.
The United States currently produces more nighttime light than any other nation, with China, India, Canada and Brazil rounding out the top five brightest countries in terms of total luminosity.
The most significant increases in artificial lighting occurred in developing regions, especially sub-Saharan Africa and Southeast Asia. Somalia, Burundi and Cambodia led this transformation, followed by several African countries including Ghana, Guinea and Rwanda.
“For decades, we’ve held a simplified view that the Earth at night is just getting steadily brighter as human population and economies grow,” explained Zhe Zhu, a remote sensing professor and director of the University of Connecticut’s Global Environmental Remote Sensing Laboratory, who led the research published Wednesday in Nature journal.
“We discovered that the Earth’s nightscape is actually highly volatile,” Zhu added. “The planet’s lighting footprint is constantly expanding, contracting and shifting.”
The research team utilized daily satellite observations from a U.S. government Earth-monitoring satellite, processed through NASA systems. This approach provided much more detailed data than previous studies that relied on monthly or yearly composite images.
Growing brightness in emerging economies reflects more than just city expansion, according to researchers. “This isn’t just urbanization. It is a massive expansion of energy access,” Zhu noted. “These numbers represent a profound shift as entire regions transition from near-total darkness to becoming part of the global electric network.”
However, some regions experienced dramatic lighting decreases due to conflict and infrastructure breakdown. Countries including Lebanon, Ukraine, Yemen and Afghanistan saw major light loss as warfare damaged electrical systems. Similar declines occurred in Haiti and Venezuela, where economic instability and unreliable power supplies caused the dimming.
“In Ukraine, we observed a sharp, sustained decrease in light that aligned perfectly with the escalation of the conflict in February 2022,” Zhu said, referring to Russia’s large-scale invasion. “We see similar abrupt darkness falling over regions in the Middle East during periods of conflict.”
Europe stood out for different reasons, showing a 4% overall reduction in nighttime brightness due to intentional policy changes and technological improvements.
“It is driven by a widespread shift from older, less-efficient streetlights like high-pressure sodium lamps to newer, directional LED systems, as well as strict national energy-efficiency mandates and dark-sky conservation efforts,” Zhu explained. “Europe is fascinating because it presents a very structured dimming pattern.”
France emerged as a global leader in dark-sky preservation and energy efficiency requirements, according to the study.
Co-author Christopher Kyba, who teaches nighttime light remote sensing at Germany’s Ruhr University Bochum, highlighted France’s innovative approach: “The dimming in France that took place because of deliberate decisions to turn streetlights off late at night when there is no longer any activity on the streets is extraordinary. It will be very interesting to see how this develops over time, and whether this practice expands beyond France.”
The United States showed a 6% net increase in lighting during the study timeframe, but with notable regional variations.
“Geographically, the USA offers a microcosm of this global light complexity. The West Coast largely brightened, consistent with population growth and vibrant tech economies. However, much of the East Coast and Midwest actually dimmed. This was driven by de-densification in older urban cores, the decline of certain manufacturing sectors, and aggressive adoption of smart, energy-efficient city lighting programs like those in Washington, D.C., and Chicago,” Zhu observed.
Artificial lighting on a massive scale began with gas-powered street lamps in early 1800s cities, followed by electric illumination later that century. This progression has continued steadily, creating the glowing urban landscapes that now obscure most stars visible to the naked eye.
“Light pollution has profound ecological consequences, disrupting nocturnal ecosystems, animal migrations and human circadian rhythms,” Zhu warned.
