Wednesday, December 05, 2012

Dazzling Video Of World Cities At Night From Space

NASA Releases Latest "Night Sky" Video View Of World

The night side of Earth twinkles with light, and the first thing to stand out is the cities. "Nothing tells us more about the spread of humans across the Earth than city lights," asserts Chris Elvidge, a NOAA scientist who has studied them for 20 years, responding to the latest NASA video space-view of the world's cities at nighttime.

This new global view and animation of Earth's city lights is a composite assembled from data acquired by the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. The data was acquired over nine days in April 2012 and thirteen days in October 2012. It took satellite 312 orbits and 2.5 terabytes of data to get a clear shot of every parcel of Earth's land surface and islands. This new data was then mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet.

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.

Light Pollution From City Lights - A Controversy

The International Dark Sky Association, an organization fighting light pollution around the world, cites photographic data like this night view of the world's cities to demonstrate the deletereous effects extraneous city night lighting has on the environment.

Says the IDA, "Once a source of wonder--and one half of the entire planet’s natural environment—the star-filled nights of just a few years ago are vanishing in a yellow haze. Human-produced light pollution not only mars our view of the stars; poor lighting threatens astronomy, disrupts ecosystems, affects human circadian rhythms, and wastes energy to the tune of $2.2 billion per year in the U.S. alone.

They promote the idea to city planners to "Light what you need, when you need it. We know some light at night is necessary for safety and recreation. We work with manufacturers, planners, legislators, and citizens to provide energy efficient options that direct the light where you want it to go, not uselessly up into the sky."

Credit: NASA Earth Observatory/NOAA NGDC

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