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posted by on Wednesday February 22 2017, @01:02PM   Printer-friendly
from the i-can-be-a-planet-too! dept.

Scientists against the demotion of objects like Pluto, Eris, Sedna, etc. to "dwarf planet" status have crafted a new definition:

It's no secret that Alan Stern and other scientists who led the New Horizons mission were extremely displeased by Pluto's demotion from planet status in 2006 during a general assembly of the International Astronomical Union. They felt the IAU decision undermined the scientific and public value of their dramatic flyby mission to the former ninth planet of the Solar System.

But now the positively peeved Pluto people have a plan. Stern and several colleagues have proposed a new definition for planethood. In technical terms, the proposal redefines planethood by saying, "A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters." More simply, the definition can be stated as, "round objects in space that are smaller than stars."

From the proposal:

The eight planets recognized by the IAU are often modified by the adjectives "terrestrial," "giant," and "ice giant," yet no one would state that a giant planet is not a planet. Yet, the IAU does not consider dwarf planets to be planets. We eschew this inconsistency. Thus, dwarf planets and moon planets such as Ceres, Pluto, Charon, and Earth's Moon are "fullfledged" planets. This seems especially true in light of these planets' complex geology and geophysics. While the degree of internal differentiation of a given world is geologically interesting, we do not use it as a criterion for planethood in the spirit of having an expansive rather than a narrow definition.

Here's another article about the significance of the New Horizons mission. New Horizons will fly by 2014 MU69 on January 1, 2019.


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  • (Score: 2) by tangomargarine on Wednesday February 22 2017, @03:57PM

    by tangomargarine (667) on Wednesday February 22 2017, @03:57PM (#470235)

    "Planet" already covers everything from Mercury to Jupiter

    asteroid belt

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  • (Score: 2) by theluggage on Wednesday February 22 2017, @04:44PM

    by theluggage (1797) on Wednesday February 22 2017, @04:44PM (#470266)

    asteroid belt

    Sorry - ambiguous - I meant "the range of planet types from Mercury to Jupiter".

    • (Score: 2) by tangomargarine on Wednesday February 22 2017, @05:07PM

      by tangomargarine (667) on Wednesday February 22 2017, @05:07PM (#470278)

      'planet' already covers everything that's already a planet

      Department of Redundancy Department
      If what you mean is "there are no dwarf planets from the Sun out to Jupiter"...

      Ceres (/ˈsɪəriːz/;[18] minor-planet designation: 1 Ceres) is the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter. Its diameter is approximately 945 kilometers (587 miles),[6] making it the largest of the minor planets within the orbit of Neptune. The 33rd-largest known body in the Solar System, it is the only dwarf planet within the orbit of Neptune.[c][19]

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      • (Score: 2) by maxwell demon on Wednesday February 22 2017, @09:12PM

        by maxwell demon (1608) on Wednesday February 22 2017, @09:12PM (#470430) Journal

        If you engage your brain, it's fairly obvious what was meant: The term "planet" already covers objects of such a wide range of different properties ranging from Mercury (a relatively small rock ball) to Jupiter (a gigantic gas ball).

        --
        The Tao of math: The numbers you can count are not the real numbers.
        • (Score: 2) by tangomargarine on Thursday February 23 2017, @03:44PM

          by tangomargarine (667) on Thursday February 23 2017, @03:44PM (#470731)

          I did engage my brain. The point they were making was totally wrong.

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          "Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
          • (Score: 2) by theluggage on Thursday February 23 2017, @05:02PM

            by theluggage (1797) on Thursday February 23 2017, @05:02PM (#470770)

            I'll try again: The term "Planet" already covers a range of bodies as diverse as gas giants (Jupiter) and small, rocky worlds (Mercury) so its never going to be sufficient as a term for classifying objects. That clear enough?

            • (Score: 2) by tangomargarine on Thursday February 23 2017, @05:53PM

              by tangomargarine (667) on Thursday February 23 2017, @05:53PM (#470791)

              Crystal. Thanks.

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    • (Score: 2) by FatPhil on Wednesday February 22 2017, @11:13PM

      by FatPhil (863) <reversethis-{if.fdsa} {ta} {tnelyos-cp}> on Wednesday February 22 2017, @11:13PM (#470506) Homepage
      If he thought that you were implying that the planets stop at Jupiter, and that Saturn..Neptune don't count as planets in your eyes, then he's cleary having a argument with an imaginary opponent.

      It's true you could have worded it in a more spoon-feedy manner, but it was clear enough what you meant, IMHO, as you couldn't have meant the above, and therfore some other range was being expressed by your "from .. to ..".
      --
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      • (Score: 2) by tangomargarine on Thursday February 23 2017, @03:47PM

        by tangomargarine (667) on Thursday February 23 2017, @03:47PM (#470732)

        Oh, range of *properties*? I was reading that as "geographical range," and past Jupiter was excluded because it was common knowledge dwarf planets were in that area.

        Guess my eyes skated over "types" for some reason :P

        --
        "Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"