Nasa unveiled the most accurate and most detailed images of the Earth at night at a news conference at the American Geophysical Union meeting in San Francisco.
While the composite cloud-free images and animations recorded by the Suomi National Polar-orbiting Partnership satellite are truly stunning they also reveal human effects on the planet's landscape far more effectively than Nasa's previous Blue Marble daytime shots of Earth. "Night time imagery provides an intuitively graspable view of our planet," said William Stefanov, a geoscientist in Nasa's International Space Station programme office. "City lights are an excellent means to track urban and suburban growth, which feeds into planning for energy use and urban hazards, for studying urban heat islands, and for initializing climate models."
The equipment onboard Suomi NPP includes the Visible Infrared Imaging Radiometre Suite (VIIRS) -- a low light sensor which allows the satellite to distinguish night lights with 250 times the dynamic range than previous satellites.
VIIRS also uses a "day-night band" to analyse the sources and intensity of light emissions and reflections in the night to provide a better understanding of the human global footprint.
To create the images, data sent from Suomi twice per day to a ground station in Svalbard Norway was mapped onto the earlier Blue Marble pictures. In the ones above, light-producing phenomena such as aurora and fires have been digitally removed to create a more focused look at the city lights.
The day-night band was able to produce such high resolution pictures using a repeated scanning technique and then responding to the light levels of the generated pixels to amplify darker images and prevent brighter ones from oversaturating. "The night is nowhere as dark as we might think," said Steven Miller, an atmospheric scientist at Colorado State University. "In fact, the Earth is never really dark. And we don't have to be in the dark about what is happening at night anymore either."
The images and animations as well as Google Earth files are available for download via the Earth Observatory website.
This article was originally published by WIRED UK
