On August 25, 2000, the Moderate-resolution Imaging Spectroradiometer (MODIS) acquired thisspectacular image of a region in Africa's Sahara Desert, including thesouthern part of the border between Algeria and Libya. Three large rockmassifs appear to be pushing up from beneath red sand dunes: from leftto right are the Tassili, Tadrart-Acacus, and Amsak massifs. Differentrock types account for rock colors varying from dark brown (Acacus) tothe pale tone of Amsak eastern portion (Amsak Mellet means Pale Amsak inthe local Tuareg dialect).
The dendritic structures of ancient riverbeds are clearly visible in theAcacus-Amsak region. Multidisciplinary studies (includingpaleo-climatology and paleo-botany) suggest that this area was wetduring the last glacial era, covered by forests and populated by wildanimals. On the same rocks, archaeologists have found a large number ofrock paintings and engravings, faint tracks of one of the most ancientcivilizations of the world. Starting about 12,000 years ago, thehunters rapidly learned domestication of buffalo and goat, and developedone of the first systems of symbolic art. Extremely dry weatherconditions began here about 5,000 years ago, perhaps leading to thedecline of this civilization but helping to preserve their ancientmasterpieces.
This natural color image (top) was produced using three MODIS bandscorresponding to red, green, and blue wavelengths. The ground resolutionis 250 meters per pixel and was made by "injecting" the high-resolutionred channel into lower resolution green and blue channels. The imagewas processed by Telespazio's Earth Observation division, in its newproducts development facility in Rome, Italy. The MODIS sensor fliesaboard NASA's Terra spacecraft, launched in December 1999.
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Image courtesy Luca Pietranera, Telespazio , Rome, Italy
