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  1. #11
    canopus56's Avatar
    canopus56 Guest

    Default IAU updates scientific definition of planet to match current knowledge



    Ed wrote:

    Your assumption is that the science should be conducted as a democracy
    - as distinguished from an atmosphere or process of free inquiry.

    In science, unlike the political process, proposals (hypotheses) are
    first judged by their inherent strength - their ability to explain
    observed facts in nature - independent of their proponent. A small
    minority of inherently uncertain matters may need to be given
    provisional definitions based on a consenus vote, but this rare.


    Before you conclude that the result of the IAU vote is improper and
    needs to be revisited, I ask you this:

    What definition best explains the our current knowledge of the physical
    structure of the solar system: the classical definition or IAU
    resolutions 5A and 6A?

    Granted the resolution 5A definition does appear to an ambiguity that
    you have focused on - the phrase "has cleared the neighbourhood around
    its orbit," but this can fixed by further amendment.

    Brian Tung, in another thread, I believe refered you to Steven Soter's
    "What is a Planet?"
    article:

    http://arxiv.org/ftp/astro-ph/papers/0608/0608359.pdf

    Regardless of whether the IAU actually discussed Soter's paper, his
    reasoning for the "clearing" criteria seems sound. As shown in his
    Figure 3, there is a clear physical gap for the "clearing" of orbits
    for the eight planets not seen for trans-neptunian objects (TNOs) -
    that is inherently related to the nature of the eight planets.

    "Clearing" in Soter's use of the term does not mean a complete vacuming
    of an orbit or all matter. Thousands of small meteorites and some
    asteriods remain. For example, in the "clearing" of the Earth's orbit,
    10^-6 of Earth's mass (0.000001) remains in rubble and small bodies in
    Earth's orbit. In the case of Pluto, a much for massive ratio of
    rubble to pluton exists - 10^-1/2 or 0.32 or 32% - is estimated to
    remain in Pluto's orbit.

    "Clearing" in Soter's sense is compatible with the quote of Alan Stern,
    of NASA's Pluto Mission, attributed to him in another thread: "But Dr
    Stern pointed out that Earth, Mars, Jupiter and Neptune have also not
    fully cleared their orbital zones. Earth orbits with 10,000 near-Earth
    asteroids. Jupiter, meanwhile, is accompanied by 100,000 Trojan
    asteroids on its orbital path."

    Resolution 5A and 6A are an advance in the definition of the term
    "planet" over the classical or original IAU resolution because:

    a) it better harmonizes our current knowledge of TNOs, the Kupier Belt
    and the Oort cloud relative to the "inner" solar system;

    b) it is a classification that is based on defensible physical
    characteristics of traditional 8 planets vs. other cateogries of
    objects.

    If you feel that Resolutions 5A and 6A are not an improvement over the
    classical definition or the initial IAU resolution, than what facts
    support your claim of the superiority of either of those alternative
    defintions?

    Let set aside for the moment your concern of the fairness of the IAU
    process - which is a distinctly different question of the scientific
    merit of the definition.

    Please, review Soter's paper and his Figure 3, before you respond.

    - Canopus56


  2. #12
    Wally Wonderful's Avatar
    Wally Wonderful Guest

    Default IAU updates scientific definition of planet to match currentknowledge



    canopus56 wrote:


    I am resisting what I would like to say. One word would cover it. You did not
    know Clyde Tombaugh but yet you know very much about him and what his
    feelings would be! Pat your self .............. on the ass!
    jw





 

 
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