• MODIS Pic of the Day 18 December 2022

    From Dan Richter@1:317/3 to All on Sun Dec 18 11:00:46 2022
    December 18, 2022 - Richat Structure

    Richat
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    This true-color image of the “Blue Eye of the Sahara” was acquired by
    the Moderate Resolution Imaging Spectroradiometer (MODIS) on board
    NASA’s Aqua satellite on December 15, 2022.

    The startling circular structure, more properly known as the Richat
    Structure, is a geological formation in Mauritania’s sand-swept Maur
    Adrar Desert, which is also part of the Western Sahara Desert. The
    peculiar round shape, with concentric rings of ancient weathered rock,
    tucks in close to spectacular rocky cliffs—and both are surrounded by
    vast orange-toned sand seas, where the ripples of tall dunes are easily
    seen from space. Combined together, this feature has captured the
    interest of scientists ever since it was first photographed by the
    Gemini crew in the 1960s.

    Early speculation was that the round shape was the result of an impact
    crater created when an object fell from space and struck the Earth’s
    surface. Further study shows that the Richat Structure was initially
    formed primarily by volcanic activity many millions of years ago,
    roughly around the time that the supercontinent of Pangea began to pull
    apart. During that turbulent time, a lengthy series of eruptions
    created a volcanic dome, which hardened into an elliptical shape. The
    slow erosion by wind and water (the region was not always desert)
    slowly exposed the onion-like rings that we see today. The rocks that
    form the center of the Richat Structure are older than those found in
    the outer rings.

    Image Facts
    Satellite: Aqua
    Date Acquired: 12/15/2022
    Resolutions: 1km (69.6 KB), 500m (171.6 KB), 250m (82.8 KB)
    Bands Used: 1,4,3
    Image Credit: MODIS Land Rapid Response Team, NASA GSFC



    https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2022-12-18

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