Black and Blue All Over – The imagery behind NASA’s marbles

NASA is well known for its astronaut program, space exploration, rockets, satellites, remote sensing, and numerous other scientific endeavors, but are you familiar with their marbles? They now come in two flavors, a blue marble and a black marble, both depicting stunning visual displays of our planet.

The blue marble portrays a daytime view of our planet as viewed from space, and the recently released black marble reveals a novel nighttime view. Both are global composites of images collected from orbiting satellites, which have been seamlessly stitched together into cohesive representations of the entire surface of the planet.  The marbles are available for you to view and download through the NASA website, either as static individual images or as rotating animations.

Blue Marble: Next GenerationBlue Marble: The original “blue marble” was a photo acquired by astronauts onboard Apollo 17 as they departed Earth on their way to the moon, 40 years ago today, on December 7, 1972. The now iconic photo of Earth has since inspired a host of similar images, acquired from both astronauts and satellites alike, as well as motivation to generate integrated image composites of the entire planet. NASA released the first of these global composites in 2002. This version of the Blue Marble was created using imagery from the MODIS sensor onboard NASA’s Terra satellite. MODIS (Moderate Resolution Imaging Spectroradiometer) is a multispectral instrument collecting measurements in 36 spectral bands (visible to long-wave infrared). But only those bands in the visible portion of the spectrum were used for the Blue Marble in order to generate a true-color likeness of the planet. An updated version of this composite, the Blue Marble: Next Generation, was released in 2005. Although similar to the previous version, and also based on imagery from the MODIS sensor, this new version has no clouds and twice the level of detail (500m pixels versus 1km pixels).

Black MarbleBlack Marble: Most recently, on December 5, 2012, NASA released its first nighttime composite of the planet, appropriately named the Black Marble. Imagery for this version was obtained from the multispectral VIIRS instrument onboard the Suomi NPP (National Polar-orbiting Partnership) satellite, launched just over a year ago in 2011. VIIRS (Visible Infrared Imaging Radiometer Suite) measures 22 spectral bands in the visible to long-wave infrared, including a panchromatic day/night band. This day/night band is particularly capable of recording images in low-light conditions, and is the source of imagery utilized for generating the Black Marble composite.

As would be expected, the imagery used to create the marbles represents the foundation for many different scientific studies. While the science behind the marbles is indeed important, their visual beauty alone is inspiring and a meaningful reminder of the interconnected nature of our planet.

For more details on NASA’s Blue Marble: http://earthobservatory.nasa.gov/Features/BlueMarble/

For more details on NASA’s Black Marble: http://www.nasa.gov/mission_pages/NPP/news/earth-at-night.html

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