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

Don't worry, it's been thoroughly discussed.


If you're implying that everyone interested agrees that this is the
right way
to classify planets, I'm not persuaded.

Anyway, I couldn't endorse this as a primary classification system.
The most important
characteristic of a planets is its composition, not its mass.

That's true, but composition is entirely different and much more
complex, the Meghar scale is a mass scale, and thus straightforward,
especially in an era where our knowledge of exoplanets is still
primitive, and mass and orbit are the only really clear data we have
at this point.

That doesn't imply it's useful. We already know the mass, and we
already
use (for exoplanets) common terms to describe the mass range, so what
purpose is there in making this a formal scale? You haven't answered
that.

A compositional scale is an entirely different scale,
and I encourage you to develop one, but right now the Meghar scale is
the best one out there for describing the masses and sizes of planets
with our solar system as the reference point, and it is far more
descriptive and exoplanet friendly than the crap that came out of the
IAU in the last few years. That is really a black mark on the IAU that
isn't going away.


I don't know why you have a problem with the IAU decision, assuming
you mean the definition of 'planet'. It's a non-arbitrary definition
that will
clearly be applicable to other solar systems as well. The 'Meghar
scale'
is not such.

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.

You have to make an arbitrary decision of your breakpoints in any
scale, this scale happens to coincide remarkably with OUR solar
system.

That is not a merit, given that the system should apply to all planets
in
the universe.

Groups based on mass, like the 'Meghar scale', don't really solve the
problem, they just
ignore it.

It ignores everything except mass. We further refine and distinguish
super Earths and gas planets, gas giants, super giants, solid metal
death star planets, brown dwarfs, dwarf stars, etc.

So, this proposes that the top-level classification should be mass,
with
further distinctions lower down. This is almost as ridiculous as an
analogous classification of animals first on size.

In this scheme,
'dwarf' is qualitative and descriptive, just because Ceres and Pluto
are dwarfs doesn't make them non-planets, just as dwarf humans are not
non-humans. The IAU really took their eye off the 'ball' on this one.

Just because you don't see the debate, doesn't mean it didn't happen,
just as if you don't see planets, doesn't mean they don't exist.

I'm not sure what you're trying to get across here.

Andrew Usher