Subtle changes are occurring in the nighttime hours on planet Earth, according to NASA scientists who say an unexpected pattern has surfaced in new maps of the world’s artificial light.
The highly detailed new maps offer a revealing look at how humans are reshaping the nighttime world around our planet, as seen in patterns of variation in artificial light. The findings were detailed in a recent study by an international team of researchers, including scientists from the American space agency.
Drawing from NASA’s Black Marble Data, the maps indicate that, in addition to gradual shifts in the luminous displays that brighten the portions of Earth furthest from the Sun at any given time, there are also some surprises. These include what were recently characterized as “a world flickering with industrial booms and busts, construction, and blackouts,” driven by a range of factors, including industrial efforts.
Black Marble: Peering into the Visible Infrared
Black Marble is a product suite specifically designed to track changes in human infrastructure driven by artificial light. The system is calibrated each day to ensure accurate, up-to-date scientific observations.
“Black Marble is playing a vital role in research on light pollution, illegal fishing, fires, disaster impacts and recovery, and human settlements and associated energy infrastructures,” according to a NASA FAQ page detailing its capabilities.
At the core of Black Marble is the Visible Infrared Imaging Radiometry Suite (VIIRS), a system that is hosted on a trio of satellite platforms that include the National Oceanic and Atmospheric Administration’s NOAA-20 and NOAA-21, as well as the Suomi NPP.
Equipped with a unique sensor that features gain settings calibrated to capture high-quality low-light imagery of Earth by night, Black Marble offers a wealth of scientific data and stunning imagery of how humans are reshaping the planet through artificial light, capturing light across multiple wavelengths. Specifically, these include green and near-infrared light, as well as specialized filtering techniques for a variety of important applications.
What Maps of Earth’s Artificial Light Reveal
One thing the new maps reveal is how brightness from artificial light varies across densely populated regions, as seen in areas that lie between about 60 degrees south and 70 degrees north.
The new imagery, featured on NASA’s Earth Observatory page, shows areas of yellow and gold, indicating regions that saw significantly more illumination during the period the data were collected, between 2014 and 2022.
Additionally, the maps show purple areas indicating the opposite: greater dimming over the study period.
“Our findings challenge the prevailing perspective that changes in light radiance are largely gradual and unidirectional,” wrote the authors of a recent study published in Nature detailing what the maps reveal. “Instead, the nightlights of Earth are surprisingly dynamic, characterized by frequent and coexisting brightening and dimming.”
The research team found that, on average, every location where changes in artificial light were taking place “underwent 6.6 distinct shifts over the 9 years.”
Global radiance appears to have increased by an estimated 34 percent, the researchers say, although they note that this apparent surge in artificial lighting also effectively masked areas where significant dimming was taking place.
One area where this was particularly evident was on the U.S. West Coast, where cities appear to have increased in brightness proportionally with population increase, whereas along the East Coast, dimming was observed, which the researchers linked to more widespread use of energy-efficient alternatives like LED lighting, along with subtle economic changes and other factors.
Surges in the Eastern World
The areas with the greatest increase in artificial light at night were China and northern India, both of which coincided with areas of ongoing urban development.
Similar to patterns across the Eastern U.S., countries like the United Kingdom and France—especially in major cities like Paris—saw reduced artificial light pollution as LED lighting and other energy-saving conservation efforts were adopted. The sharpest overall drop in lighting occurred near the end of the study, when an energy crisis began impacting many European countries following the Russian invasion of Ukraine.
The new maps were featured on the cover of the recent edition of the journal Nature that featured the study, and can also be seen at NASA’s Earth Observatory page.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.