6 December 2012
Last updated at 14:32
Scientists at Nasa have released a number of new images of planet Earth at night.
The global composite images were constructed using cloud-free night images from a new Nasa and National Oceanic and Atmospheric Administration (NOAA) satellite.
According to Nasa, the images show the light generated by natural and human-built phenomena across the planet in greater detail than ever before.
The images were acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite. It has a new sensor that can detect the nocturnal glow produced by Earth's atmosphere and the light from a single ship in the sea.
Here is part of the Atlantic coast of South America on the night of 20 June 2012.
The VIIRS "day-night band" detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe signals such as gas flares, auroras, wildfires, city lights, and reflected moonlight.
“The instrument can capture images on nights with or without moonlight, producing crisp views of Earth's atmosphere, land and ocean surfaces,” says Steve Miller, a researcher at NOAA's Colorado State University Cooperative Institute for Research in the Atmosphere.
"For all the reasons that we need to see Earth during the day, we also need to see Earth at night," says Mr Miller. "Unlike humans, the Earth never sleeps."
On 13 October 2012 the satellite captured this night-time view. "The Nile River Valley and Delta comprise less than 5% of Egypt’s land area, but provide a home to roughly 97% of the country’s population. Nothing makes the location of human population clearer than the lights illuminating the valley and delta at night," says Nasa.