NASAのインスタグラム(nasa) - 6月13日 06時43分

Brazil's World Cup 2014 host cities are seen at night in this satellite image from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite, captured on August 4, 2013.

Home to roughly 190 million people, Brazil is the largest country in South America and the fifth largest in the world by area (8.5 million square kilometers). As shown in the image above, Brazil stretches about 4,000 kilometers from north to south and from east to west. The coastal cities of São Paulo and Rio de Janeiro (below) are the centerpieces of the most densely populated part of the country. In 2014, twelve cities are hosting World Cup matches,including Brasilia, Belo Horizonte, Manaus, Fortaleza, Cuiaba, Curitiba, Porto Alegre, Natal, Recife, Salvador, Rio de Janeiro, and São Paulo.

The nighttime view was made possible by the VIIRS day-night band which detects light in a range of wavelengths from green to near-infrared, and uses light intensification to enable the detection of dim signals. The instrument can sense light 100,000 times fainter than the conventional visible light sensors, making it very sensitive to things like moonlight and city lights.

Unlike a film camera that captures a photograph in one exposure, VIIRS produces an image by repeatedly scanning a scene and resolving it as millions of individual picture elements, or pixels. The day-night band goes a step further, determining on-the-fly whether to use its low, medium, or high-gain mode. If a pixel is very bright, a low-gain mode on the sensor prevents the pixel from over-saturating. If the pixel is dark, the signal will be amplified.

Suomi NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense.

Image Credit: NASA/Suomi NPP/Earth Observatory
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