Re: Short filk: Planets

In article <garym-1ADEC6.07111626082006@xxxxxxxxxxxxxxx>,
Gary McGath <garym@xxxxxxxxxxxxxxxx> wrote:
In article <44ef65b0$1@kcnews01>,
Joseph Kesselman <keshlam-nospam@xxxxxxxxxxx> wrote:

Arthur T. wrote:
Not as relevant, but suggestive that these definitions won't
hold up:

Or suggestive that most will accept whatever decision gets made. Which
is my own take, not that this is anywhere near my fields of expertise --
I don't care whether there's a new category and/or where the dividing
line is drawn, just so long as someone establishes a clear definition.

But is the one that's been adopted a clear one?

--
Gary McGath http://www.mcgath.com
Prosecute Bush, not newspapers.

The definition is clear, if badly written.

A Planet is an object thate has enough mass to achieve "hydrostatic
equilibrium" which is just a fancy way of stating gravity makes it
spherical.

It may not be a satelite of another planet.

It must have sufficient mass to have "cleared it's orbit". THese are the
weasle words. Earlier drafts had phrases such as "dominant in it's orbit"
contains the majority of it's mass etc.

Basically Pluto is an interesting Kuiper belt object. Since these objects
formed by a diferent process than the 8 planets it is reasonable to
classify them differently.


Mark E. Horning, Physicist
Phoenix, Arizona

.

Relevant Pages

  • Re: Strength of Materials
    ... orbit around the Sun, has sufficient mass for its self-gravity to ... "If Neptune had cleared its zone, Pluto wouldn't be there," he added. ... content to keep Pluto as a planet, and, when you discover something new ...
    (sci.physics)
  • Re: Planet & Satellite Paradox (just for fun!)
    ... Orbit is elliptical, ... Without transforms, without Doppler correction, the apparent mass ... observers on either planet would see the opposing planet as having ...
    (sci.physics.relativity)
  • Re: "Pluto Now Called a Plutoid"
    ... its orbit, and is not a satellite. ... Now we can ask "How many 'dwarf exoplanets' with a mass greater than ... The IAU's definition of a planet is extremely flawed for a number of ... Jupiter mass brown dwarf and one Jupiter mass planet ...
    (rec.arts.sf.science)
  • Re: "Pluto Now Called a Plutoid"
    ... "A planet is a celestial body that is in orbit around the Sun, ... Jupiter mass brown dwarf and one Jupiter mass ... The new definition is still explicitly limited to just the solar system ...
    (rec.arts.sf.science)
  • Re: "Pluto Now Called a Plutoid"
    ... "A planet is a celestial body that is in orbit around the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape, and has cleared the neighbourhood around its orbit." ... So yes, it would likely be called a planet, even under the IAU's definition. ... a planet 70 percent as massive as the Earth _would_ clear its region in the Kuiper belt. ... It would be approximately as capable of clearing objects from its orbit as Mars is, and Mars is considered a planet. ...
    (rec.arts.sf.science)
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