Skip to Main Content

Unprecedented New Images of Earth at Night

Pin it

Dec. 5, 2012:  Today at the American Geophysical Union meeting in San Francisco, scientists unveiled an unprecedented new look at our planet at night. A global composite image, constructed using cloud-free night images from a new NASA and National Oceanic and Atmospheric Administration (NOAA) satellite, shows the glow of natural and human-built phenomena across Earth in greater detail than ever before.

"For all the reasons that we need to see Earth during the day, we also need to see Earth at night," said Steve Miller, a researcher at NOAA's Colorado State University Cooperative Institute for Research in the Atmosphere. "Unlike humans, the Earth never sleeps."

Earth at Night (splash)
This image of the continental United States at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. The image was made possible by the satellite's "day-night band" of the Visible Infrared Imaging Radiometer Suite (VIIRS), which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires and reflected moonlight. Credit: NASA Earth Observatory/NOAA NGDC >> High-resolution download and more information

Many satellites are equipped to look at Earth during the day, when they can observe our planet fully illuminated by the sun. With a new sensor aboard the NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite launched last year, scientists now can observe Earth's atmosphere and surface during nighttime hours. The sensor, called "VIIRS" (short for Visible Infrared Imaging Radiometer Suite), is sensitive enough to detect the light from a single ship in the sea.

The Edge (signup)

The day-night band of VIIRS observed Hurricane Sandy, illuminated by moonlight, making landfall over New Jersey on the evening of Oct. 29. Night images showed the widespread power outages that left millions in darkness in the wake of the storm. With its night view, VIIRS is able to detect a more complete view of storms and other weather conditions, such as fog, that are difficult to discern with infrared, or thermal, sensors. Night is also when many types of clouds begin to form.

"NOAA's National Weather Service is continuing to explore the use of the day-night band," said Mitch Goldberg, program scientist for NOAA's Joint Polar Satellite System. "The very high resolution from VIIRS data will take forecasting weather events at night to a much higher level."

Unlike a camera that captures a picture in one exposure, the day-night band produces an image by repeatedly scanning a scene and resolving it as millions of individual pixels. Then, the day-night band reviews the amount of light in each pixel. If it is very bright, a low-gain mode prevents the pixel from oversaturating. If the pixel is very dark, the signal is amplified.

"It's like having three simultaneous low-light cameras operating at once and we pick the best of various cameras, depending on where we're looking in the scene," Miller said. The instrument can capture images on nights with or without moonlight, producing crisp views of Earth's atmosphere, land and ocean surfaces.

"The night is nowhere as dark as we might think," Miller said. And with the VIIRS day-night band helping scientists to tease out information from human and natural sources of nighttime light, "we don't have to be in the dark anymore, either."


Production editor: Dr. Tony Phillips | Credit: Science@NASA

More Information
› "Out of the Blue and Into the Black: New Views of the Earth at Night" (12.05.12)
› More views of Earth at night from NASA Earth Observatory
› NASA's Suomi NPP website
› Suomi NPP project website
› NOAA National Geophysical Data Center: Earth Observations Group, DMSP
› Earth "marble" imagery on Flickr
› NASA Earth Observatory: "Blue Marble: Next Generation" (2004)
› "Earth, Behind the Scenes": How VIIRS data from Suomi NPP becomes "marble" imagery (02.04.12)