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  1. #1
    Sam Wormley's Avatar
    Sam Wormley Guest


    The American Institute of Physics Bulletin of Research News
    Number 881 February 26, 2008

    The hurricanes that visit the Gulf and Caribbean in September and
    even the huge jetstream that dominates winter weather in North
    America are small compared to Jupiter's Great Red Spot. The Spot is
    a lozenge-shaped storm and is about two Earth-widths across. Like
    meteorologists who study earthly hurricanes to better understand the
    behavior of these violent storms, planetary astronomers try to
    record detailed images of the Spot to better to understand weather
    on Jupiter---a planet (with no visible solid surface at all) that is
    nothing but weather.

    Detailed images are hard to come by since the Great Red Spot is
    always on the go. First, the planet as a whole is rotating. Then
    the Spot is moving along its horizontal band, a cloud band
    stretching all the way around the planet. Then this band is moving
    relative to some of the other parallel bands at other latitudes.
    Furthermore, the Spot is revolving counterclockwise about once every
    6 Earth-days. Finally, the camera taking pictures, mounted on flyby
    missions like the Galileo or Cassini spacecraft, are themselves
    shooting through space at thousands of miles per hour.

    Xylar Asay-Davis, a scientist at the University of California at
    Berkeley, says that a further complication in sizing up the Spot is
    the fact that various clouds not actually part of the Spot are
    hovering nearby. Some of these clouds nip off parts of the Spot or
    are, in their turn, taken up into the Spot. The only true way to
    measure the true extent and motion of the Great Red Spot, he says,
    is to measure wind speeds.

    For that purpose, Asay-Davis and his colleagues have produced the
    best ever map of wind speeds on Jupiter, where the gusts are
    typically at the level of 250 miles per hour, higher than winds we
    see in hurricanes on Earth. The maps consist of tens of millions of
    velocity measurements and provide a sharp image of what's happening
    with the Spot. Indeed, according to Xylar Asay-Davis these maps
    represent the highest resolution and highest accuracy full-planet
    map ever produced.

    The maps draw on data from Galileo and Cassini and even observations
    from the Hubble Space Telescope, and are processed with
    sophisticated software. From all this number crunching, the team of
    scientists deduce that the Great Red Spot has shrunken over the past
    dozen years. The Spot has survived for at least 300 years and is
    in no danger of dissipating, says Asay-Davis. Those nearby clouds,
    regularly bumping into Spot can subtract or add energy from it.

    Asay-Davis's reported his findings at a meeting of the American
    Physical Society fluid dynamics division.

    PHYSICS NEWS UPDATE is a digest of physics news items arising
    from physics meetings, physics journals, newspapers and
    magazines, and other news sources. It is provided free of charge
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    physicists. For that reason, you are free to post it, if you like,
    where others can read it, providing only that you credit AIP.
    Physics News Update appears approximately once a week.

  2. #2's Avatar Guest


    On Feb 26, 6:07 pm, Sam Wormley <> wrote:

    "Out, damn'd spot! out, I say! ... Yet who would have thought the old
    man to have had so much blood in him?"

    Tom Davidson
    Richmond, VA

  3. #3
    rmollise's Avatar
    rmollise Guest


    On Feb 26, 5:40 pm, "" <> wrote:

    What a sigh is there! The heart is sorely charged.



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