NASA scientists just released new global maps of Earth at night, providing the clearest-yet views of the patterns of human settlements across our planet and the light we bring to our night skies. Until 2012, nighttime photos of the planet were only available to a small group of scientists through military satellites and astronaut photography. But with the launch of the Suomi National Polar-orbiting Partnership (NPP) satellite in October 2011 by NASA, the National Oceanic and Atmospheric Administration (NOAA), and the Department of Defense, we all get to see the spread of humanity.
The first thing you notice are the large cities and their spider-web-like sprawl followed by the small cities and towns strung out along (mostly) invisible highways. Other regions, such as the Bakken oil fields in North Dakota, are dotted with the lights from oil drilling and gas flaring. Next door neighbors North and South Korea show a dramatic contrast in the use and spread of artificial lighting. Off the South Korean coast, hundreds of fishing boats light up the waters to increase their catch.
Suomi NPP is a civilian science satellite that provides photos and data to scientists within minutes to hours. It carries a low-light sensor that can distinguish night lights with six times better spatial resolution and 250 times better resolution of lighting levels than any previous satellite before.
The satellite observes nearly every location on Earth at roughly 1:30 p.m. and 1:30 a.m. (local time) each day, as it images the planet in vertical 2,000-mile (3,000 km) strips from pole to pole. The satellite uses the Visible Infrared Imaging Radiometer Suite (VIIRS), which can detects light reflected from Earth’s surface and atmosphere in 22 different wavelengths or colors.
A research team in the Earth Observing Satellite Data and Information System (EOSDIS) has been working to get these nighttime photos into NASA’s Global Imagery Browse Services (GIBS) and Worldview mapping tools. GIBS and Worldview allow users to see natural- and false-color images of Earth within hours of them being acquired by satellite and they’re free to scientists and the public both. By late 2017, NASA Earth scientist Miguel Román and colleagues hope to provide daily high-definition views of Earth at night.
Román and colleagues have been working on techniques to filter out sources of extraneous light such as moonlight and airglow to get a better and more consistent signal of how human-driven patterns are changing. Ultimately, they hope to observe dim light down to the level of an isolated highway lamp or a fishing boat.
Lights of Human Activity Shine in NASA’s Image of Earth at Night
Daily nighttime images might help in disaster relief by identifying areas without power, tracking sea ice movements and even helping to monitor illegal fishing. Researchers in Puerto Rico are already working with nighttime data to reduce light pollution and help protect tropical forests and coastal areas with fragile ecosystems.
Usually I’m urging all of you to look up, but clearly, looking down can be just as revealing.