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Phoebe Phobia

  1. Jun 25, 2004 #1
    The debate about the origin of Saturn's moon Phoebe is over. While it may look like an asteroid, the tiny moon actually is an icy interloper from the distant fringes of the solar system, according to new results from NASA's Cassini probe.

    Phoebe is "a frozen time capsule" from 4 billion years ago, "waiting for Cassini to come along and open it up," scientist Torrence Johnson said Wednesday in Pasadena, Calif.

    Scientists made their determination based on spectroscopic measurements of Phoebe taken when Cassini swooped within 1,280 miles of the battered and beaten moon on June 11.

    The images and measurements taken during the fly-by indicate that Phoebe is lighter than rock but heavier than ice -- similar in density to Pluto and its moon Triton. That suggests Phoebe has the same origin as those bodies on the outer edge of the solar system.

    Spectroscopic data indicates that Phoebe's surface is made of water ice, water-bearing minerals, carbon dioxide, possible clays, said Roger Clark of the U.S. Geological Survey.

    Infrared measurements indicate Phoebe's surface is very cold, about 110 degrees above absolute zero -- minus 261 degrees Fahrenheit -- in sunlight, according to John Pearl of the National Aeronautics and Space Administration's Goddard Space Flight Center in Greenbelt, Md. On the night side of the moon, the temperature drops to minus 325 degrees.

  2. jcsd
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