The Blue Marble

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The Blue Marble—Earth seen by Apollo 17 in 1972

The Blue Marble is a famous photograph of the Earth, taken on December 7, 1972, by the crew of the Apollo 17 spacecraft, at a distance of about 45,000 kilometers (28,000 miles). It is one of the most iconic, and among the most widely distributed images in human history.[1][2]

The image with the official NASA designation AS17-148-22727 reproduces the view of the Earth as seen by the Apollo crew traveling toward the Moon. The translunar coast photograph extends from the Mediterranean Sea to Antarctica. This was the first time the Apollo trajectory made it possible to photograph the south polar ice cap with the Southern Hemisphere heavily covered in clouds. Almost the entire coastline of Africa is clearly visible and the Arabian Peninsula can be seen at the northeastern edge of Africa. The large island off the coast of Africa is Madagascar. The Asian mainland is on the horizon toward the northeast.

The name has also been applied by NASA to a 2012 series of image data sets covering the entire globe at relatively high resolution, created by carefully sifting through satellite-captured sequences taken over time, to eliminate as much cloud cover as possible from the collated set of images.

The photograph[edit]

The snapshot—taken by astronauts on December 7, 1972, at 5:39 a.m. EST (10:39 UTC)—is one of the most widely distributed photographic images in existence.[2] The image is one of the few to show an almost fully illuminated Earth disk (slightly gibbous), as the astronauts had the Sun behind them when they took the image. To the astronauts, Earth had the appearance and size of a glass marble, hence the name.

History[edit]

The photograph was taken about 5 hours and 6 minutes after launch of the Apollo 17 mission,[3] and about 1 hour 54 minutes after the spacecraft left its parking orbit around the Earth, to begin its trajectory to the Moon. The time of Apollo 17's launch, 12:33 a.m. EST, meant that Africa was in daylight during the early hours of the spacecraft's flight. With the December solstice approaching, Antarctica was also illuminated.

An Indian Ocean cyclone can be seen in the top right of the image. This storm had brought flooding and high winds to the Indian state of Tamil Nadu on December 5, two days before the photograph was taken.[4]

The photograph's official NASA designation is AS17-148-22727. (NASA photograph AS17-148-22726, taken just before and nearly identical to 22727, is also used as a full-Earth image.)[5]

The photographer used a 70-millimeter Hasselblad camera with an 80-millimeter Zeiss lens.[6][7] NASA credits the image to the entire Apollo 17 crewTemplate:MdashEugene Cernan, Ronald Evans and Jack SchmittTemplate:Mdashall of whom took photographs during the mission with the on-board Hasselblad, although evidence examined after the mission suggests that Jack Schmitt was the photographer.[2]

Apollo 17 was the last manned lunar mission. No one since has been far enough from Earth to photograph a whole-Earth image such as The Blue Marble, but whole-Earth images have been taken by many unmanned spacecraft missions.

The Blue Marble was not the first clear image taken of an illuminated face of the Earth, since similar shots from the ATS-3 satellite had already been made as early as 1967.[8] Counterculture activists had been among the first to cherish these images as icons of a new global consciousness.[9] The Apollo 17 image, however, released during a surge in environmental activism during the 1970s, became a symbol of the environmental movement, as a depiction of Earth's frailty, vulnerability, and isolation amid the vast expanse of space.[1] NASA archivist Mike Gentry has speculated that The Blue Marble is among the most widely distributed images in human history.[2]

Subsequent "Blue Marble" images[edit]

Subsequent similar images of Earth (including composites at much higher resolution) have also been termed "Blue Marble" images, and the phrase "blue marble" (as well as the picture itself) is frequently used, as in the Earth flag by environmental activist organizations or companies attempting to promote an environmentally conscious image. In addition, there has also been a children's television program called Big Blue Marble. Poet-diplomat Abhay K has penned an Earth Anthem inspired by the blue marble which contains "all the peoples and the nations of the world, one for all, all for one, united we unfurl the blue marble flag".[10]Template:Better source

Imaging series 2001–2004[edit]

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In 2002, NASA released an extensive set of satellite-captured imagery, including prepared images suitable for direct human viewing, as well as complete sets suitable for use in preparing further works.[11] At the time, 1 km/pixel was the most detailed imagery available for free, and permitted for reuse[12] without a need for extensive preparatory work to eliminate cloud cover and conceal missing data, or to parse specialized data formats. The data also included a similarly manually assembled cloud-cover and night-lights image sets, at lower resolutions.

A subsequent release was made in 2005, named Blue Marble Next Generation.[13] This series of photo mosaics was produced with the aid of automated image-sifting upon images from NASA's Earth Observatory, which enabled the inclusion of a complete, cloud-free globe 'frozen in time' for each month from January to December 2004, at even higher resolution (500 m/pixel).[14] The original release of a single-image set covering the entire globe had, of necessity, not been a true reflection of the extent of seasonal snow-and-vegetative cover across both hemispheres, but this newer release closely modeled the changes of the seasons.

A number of interactive viewers for these data have also been released, among them a music visualization for the PS3 that is based on the texture data.[15][16]

Blue Marble 2012[edit]

"Blue Marble 2012" – a composite satellite image

On 25 January 2012, NASA released a composite image of the western hemisphere of Earth entitled Blue Marble 2012. The picture was widely viewed, logging over 3.1 million views on the Flickr image hosting website within the first week of release.[17] On 2 February 2012, NASA released a companion to this new Blue Marble, showing a composite image of the eastern hemisphere from data obtained on 23 January 2012.[18]

The picture is composed of data obtained by the Visible/Infrared Imager Radiometer Suite (VIIRS) instrument[18] on board the Suomi NPP satellite on 4 January 2012.[19] The data was obtained from six orbits of the Earth by the Suomi NPP over an eight-hour period.[18]

Black Marble 2012[edit]

"Black Marble" – North and South America at night[20]

On December 5, 2012, NASA released a nighttime view of Earth called Black Marble[20] during an annual meeting of Earth scientists held by the American Geophysical Union in San Francisco.[21] The images display all the human and natural matter that glows and can be sensed from space.[22] The data was acquired by the Suomi NPP satellite in April and October 2012 and then mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet.[23] The Suomi NPP satellite completed 312 orbits and gathered 2.5 terabytes of data to get a clear shot of every parcel of the Earth’s land surface. Named for satellite meteorology pioneer Verner Suomi, the satellite flies over any given point on Earth’s surface twice each day and flies 512 miles above the surface in a polar orbit.[24]

According to NASA, the nighttime views were made possible by the new satellite’s “day-night band” of the Visible Infrared Imaging Radiometer Suite. The so-called VIIRS 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. Auroras, fires, and other stray light have been removed in the case of the Black Marble images to emphasize the city lights.[23] The NASA stated that nighttime images can be used for numerous purposes:

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Earth seen by the DISCOVR satellite in 2015

Blue Marble 2015[edit]

On July 21, 2015, NASA released a new Blue Marble photograph taken by a U.S. Deep Space Climate Observatory, a solar weather and Earth observation satellite which was launched in February 2015 and will provide a near-continuous view of the entire sunlit-side of the Earth. The image was taken on July 6, 2015.[25] The photograph, of the Western Hemisphere, is centered over Central America. The Western United States, Mexico and the Caribbean are visible, but much of South America is hidden beneath cloud cover. Greenland can be clearly seen at the upper edge of the image.

The EPIC science team plans to upload 12 new color images per day to http://epic.gsfc.nasa.gov The color balance has been adjusted to approximate an image that could be seen with the average human eye. In addition to images, scientific information will be uploaded as it becomes available after in-flight calibration is complete. The science information will be ozone and aerosol amounts, cloud reflectivity, cloud height, and vegetation information. The EPIC instrument provides a unique view of the Earth from sunrise in the west to sunset in the east 12 to 13 times per day as the Earth rotates at 15 degrees of longitude per hour. Clearly visible are storms forming over the Atlantic and Pacific Oceans, major slowly moving "cloud rivers", dust aerosol plumes from Africa, the sun's reflection in the oceans, ship exhaust tracks in the clouds, rivers and lakes, and the variegated land surface patterns especially in the African deserts. The spatial resolution of the color images is about 10 km, and the resolution of the science products will be abut 20 km. Once every three months, lunar images are obtained that are the same as those viewed from Earth during our full Moon. On occasion, the other side Moon will appear in the Earth images as the Moon crosses in front of the Earth.

See also[edit]

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  • Earth Anthem, an anthem by poet-diplomat Abhay K featuring the sentence "United we unfurl Blue Marble Flag".
  • Earthrise, another iconic picture of the Earth, which was taken in 1968, aboard Apollo 8.
  • Flag of the Earth, a proposal for which features the Blue Marble photo.
  • Himawari 8, a geostationary satellite that captures a true-color picture of the Earth every 10 minutes
  • Pale Blue Dot, an image of the Earth taken by Voyager 1.
  • Stewart Brand, author who, in 1966, lobbied NASA to release a then-rumored satellite photograph of the entire Earth.
  • The Day the Earth Smiled
  • Whole Earth Catalog, an eclectic catalog compiled by Brand which was inspired in part by photographs of the Earth as a globe.

References*[edit]

External links[edit]

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  • NASA history of Blue Marble image releases

1972 photograph[edit]

21st century NASA composite images[edit]

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