Pictures of earth taken at night clearly shows the levels of urbanisation across different continents. Scientists have long been studying urbanisation and its affects on the environment. These images are assembled from data acquired by the Suomi National Polar-orbiting Partnership satellite.
A view of earth's city lights
A global composite image was constructed using cloud-free night images from a new NASA and National Oceanic and Atmospheric Administration satellite.
Continental United States at night
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.
Levels of urbanisation along coasts
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.
Composite image of world at night
The Eastern U.S., Europe, and Japan are brightly lit by their cities, while the interiors of Africa, Asia, Australia, and South America remain dark and lightly populated. This shows varying levels of urbanisation across the globe.
Image credit: NASA