Artificial light at night is more than just a convenience—it's a powerful indicator of human activity, economic trends, and environmental shifts. Using data from NASA's Black Marble product, scientists have mapped nearly a decade of changes in nighttime illumination across the globe. This analysis, published in Nature in April 2026, reveals a planet painted in golds and purples, where economic booms, policy changes, and even blackouts flicker across the surface. Below, we explore the key findings and the technology behind this luminous portrait.
What is the Black Marble product from NASA?
The Black Marble product is a NASA dataset that captures nighttime lights across Earth using observations from the Visible Infrared Imaging Radiometer Suite (VIIRS) sensors aboard three satellites: Suomi-NPP, NOAA-20, and NOAA-21. These sensors detect light in green to near-infrared wavelengths and filter out moonlight, auroras, and other natural sources to isolate artificial illumination. The data is available at daily, monthly, and yearly intervals, allowing scientists to track changes over time. Unlike older datasets, Black Marble offers high spatial resolution and consistent calibration, making it ideal for studying urbanization, power outages, and human migration patterns.
What did the study find about global nighttime light changes from 2014 to 2022?
According to the analysis, overall global radiance from artificial light increased by 34% between 2014 and 2022. However, this headline number hides a more complex story. The researchers discovered widespread bidirectional changes—areas of brightening (shown in yellow and gold on maps) alongside areas of dimming (shown in purple). For instance, the West Coast of the United States experienced notable brightening due to population growth, while other regions saw dimming from economic slowdowns or blackouts. These shifts often occurred right next to each other, painting a detailed picture of regional differences in human activity.
How does the VIIRS day-night band detect artificial light?
The VIIRS day-night band is a specialized sensor that captures extremely low levels of visible and near-infrared light at night. It can distinguish between city lights, partially moonlit landscapes, and even auroral emissions. To measure artificial light, the data undergoes complex filtering: scientists remove signals from moonlight (by using lunar phase models) and correct for atmospheric interference. The remaining signals represent human-generated illumination, from streetlights and buildings to vehicles and fishing boats. This technology, first deployed on the Suomi-NPP satellite in 2011, has revolutionized our ability to monitor Earth's nocturnal environment.
What do the colors on the map represent—specifically yellow, gold, and purple?
On the maps produced from the Black Marble data, yellow and gold indicate areas where artificial brightness has increased over the nearly nine-year study period. These often correspond to expanding cities, industrial zones, or regions where lighting infrastructure has been upgraded (e.g., switching to LEDs, which emit more blue-white light). Purple, in contrast, marks places where light levels have dimmed—possibly due to economic contraction, energy-saving policies, or damage from natural disasters. The maps cover inhabited land between 60°S and 70°N, excluding polar regions and most open ocean. The overlaid results are validated against ground-based measurements and satellite imagery.
How were these maps featured—and why are they important?
A version of the Eastern Hemisphere map appears on the cover of Nature (April 2026 issue), where the full study was published. That visualization includes artistic enhancements like simulated sunlight and shadows to make the data more intuitive, while the underlying brightness changes remain scientifically accurate. The maps are important because they provide a high-resolution, near-real-time monitor of human activity across the planet. For example, they can reveal recovery after natural disasters, track urbanization in developing nations, and help enforce light-pollution regulations. The work also demonstrates how satellite remote sensing can illuminate—literally—the hidden dynamics of our changing world.
What are 'bidirectional changes'—and can you give an example from the U.S.?
Bidirectional changes refer to simultaneous patterns of brightening and dimming occurring close together. The study found that this phenomenon is common globally, often reflecting contrasting local economic or demographic trends. A striking example comes from the United States: West Coast cities such as San Francisco, Los Angeles, and Seattle grew visibly brighter as populations swelled and economic activity intensified. Yet just a few hundred miles inland, rural or post-industrial areas showed dimming due to population declines or the phasing out of inefficient streetlights. Such fine-scale differences would be missed if only global averages were considered.
What real-world events can cause dimming in nighttime lights?
Dimming, shown in purple on the maps, can result from several factors. Economic downturns often lead to businesses closing and streetlight disuse. Planned outages for maintenance or energy conservation also reduce light output. Natural disasters like hurricanes, earthquakes, or wildfires can knock out power grids for extended periods. In some regions, government policies to reduce light pollution or save energy (e.g., dimming public lighting after midnight) create gradual dimming. The Black Marble data even captured abrupt dimming from the 2022 Russian invasion of Ukraine, where blackouts were common. By tracking these dips, scientists can gauge the resilience of energy infrastructure and human adaptation to crises.
How can I explore the data visually to see changes near me?
The NASA Earth Observatory website hosts interactive versions of these maps, where you can zoom into any region between 60°S and 70°N. The EO Explorer tool lets you toggle between the 2014 and 2022 layers to see brightening (yellow) and dimming (purple) at a street-level scale. You can also compare monthly composites to track seasonal variations like holiday lighting or agricultural burning. For a deeper dive, the Black Marple data is freely available through NASA's archives, and the analysis code is published alongside the Nature paper. This accessibility enables researchers, policymakers, and curious citizens alike to understand the technology and see how their own community fits into the global picture.