On Mar 20, 10:10 am, kT wrote:

FYI : The 'Meghar' Scale is now the defacto standard in planetary mass
classification. There is something there for everybody :

http://groups.google.com/group/sci.a...5d5976374dc39a

Well, I'm not sure how accepted this is, I find rather few hits for
'Meghar scale'.

Anyway, I couldn't endorse this as a primary classification system.
The most important
characteristic of a planets is its composition, not its mass. Grouping
together a 10 Me
'super-Earth' and an equal-mass giant is hardly helpful. Certainly, a
division entirely based
on factors of 10 is unreasonable here; if we do want to use arbitrary
mass thresholds (which
we shouldn't) they should be based on physical differences: for
example, the minimum mass
(on average) to attain hydrostatic equilibrium, the minimum to retain
an atmosphere, etc.

Note that _any_ system will have some borderline cases; that's the
nature of classification.
Groups based on mass, like the 'Meghar scale', don't really solve the
problem, they just
ignore it.

The credit for this goes to Willie Meghar, all I did was polish it up
and present it to the scientific community, where it was immediately
embraced by most of the hard core participants in this 'debate'.

Where may I find this 'debate'? I'd like to know what others have
thought, of course.

Andrew Usher