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ET · August 28th 06, 06:05 AM posted to sci.astro.amateur,sci.astro

wrote:
ET wrote:

However, in a 2002 paper (referenced in a subsequent paper linked from
this forum)
entitled "Regarding the criteria for planethood and proposed planetary
classification
schemes", Stern and a colleague studied the "dynamical dominance" of
bodies in the solar system and found a "gap of five orders of magnitude
between the smallest terrestrial planets
and the largest asteroids and KBOs".

Think about that. FIVE ORDERS of magnitude. That is freaking huge.

That's a five order of magnitude difference *in the Stern-Levinson
parameter*, M^2/P. The IAU could have used the Stern-Levinson
parameter, or simply drawn some line in terms of mass or radius, but
the fact is, they didn't.

Perheps because Stern insisted on including every more or less round
ice-rock
in the solar system in the list of planets?

And yet now Stern wants to assert that the glorified rocks in the
various Lagrange zones of
the 8 planets somehow disqualifies them from planethood, despite the
fact that he is
perfectly aware of the huge, qualitative difference involved.

Stern is pointing out, correctly, that the "definition" is
near-gibberish which does not define what the terms it employs mean.
And the trojan asteroids are not all "glorified rocks"; Hektor, for
example, is about 370x195 km in size. Some rock.

Some of Alan Stern's contradictions:

################################################## ###########

1st contradiction:

(originally Alan Stern writes that there is clear distinction
between "uberplanets" and "unterplanets", now 6 years later
he says there is no clear dividing line between them)

There *is* a clear gap in terms of the Stern-Levinson parameter, which,
however, the IAU does not use.

After all, don't you think that IAU included 2 of Stern's critiria for
planets?
First is that planet has to be round, second that it has cleared its
neighborhood.

The problem was that Stern then wanted to include even satellites like
Titan,
Io, Europa, Triton, Mimas and whole bunch of them, into the list of
planets.

"Hence, we define and uberplanet as a planetary body
in orbit about a star that is dynamically important enough
to have cleared its neighboring planetesimals in a Hubble time.
And we define an unterplanet as one that has not been able to do so."

That does look like a flip, but "planetesimals" is an important word
here. They go on to cook up Lambda = M^2/P, the parameter I've been
talking about, and relate it theoretically to this definition.