Hi Paul

Back then the planets were split into two groups, the "major/
principal planets" and the newly created (sub group) "minor
planets" for the relative newly discovered main belt asteroids.

Basically everthing (thats is individually observable and) moves
under the stars (out in space) can be called planet. This is the
original meaning of planet (in opposite to fixed stars). By this
definition minor planets and a dwarf planets are planets too,
but no major or principal planets like they were called back
then.

This definition would even include comets. E.g. some minor
planets, that were know as minor planets for many years, had
to be reclassified to periodic comets when looking at them
more closely with a larger scope because a coma was found.
So it doesn't make much sense to draw a very hard distinction
between periodic comets and minor planets as many minor
planets might have had a coma (and therefore have been
comets) in the far past and all comets will "become" minor
planets when they loose their ability to build a coma in the
future.
By saying this, I might start an other fruitless discussion as
unperiodic comets are usually not considered to belong to
the solar system and therefore cann't be a planet by other
definitions of the term planet.

Creating a consistent classification schema is usually very
hard. Especially if there are many different and not too well
distinguishable attributes available for classification. Right
now there even seem to be no consensus on if it should be
an inclusive (classes with subclasses), exclusive (100%
distinct classes) classifiation and if some classes might
overlap. As long as they even cann't agree on this, there
will be always quarrel on the final outcome.

If you reread my email again, you won't find any statement like
"minor planets are no planets". So there is no inconsistancy
like you try to construct artifically. Are you just hairsplitting or
arguing in favour of something ? But then please give some
arguments.

Clear skies
Wolfgang

--
Wolfgang Renz, Karlsruhe, Germany
Rz.BAV = WRe.vsnet = RWG.AAVSO

----- Original Message -----
From: "Paul Schlyter" <pausch@...>
To: <guide-user@yahoogroups.com>
Sent: Sunday, May 13, 2007 5:47 PM
Subject: Re: [guide-user] Pluto's status


> Wolfgang Renz skrev:
>
>> Honestly, Pluto is still a planet, a dwarf planet.
>> ...
>> When the first astroids were discovered, they were also clas-
>> sified as planets. But as soon as more and more of them were
>> discovered, they lost the state again and were then called minor
>> planets.
>> ...
>
> If a "dwarf planet" is a "planet", then why isn't also a "minor planet"
> a "planet"?
>
> Or you could have it the other way around if you like: if a "minor
> planet" isn't a "planet", then a "dwarf planet" isn't a "planet" either....
>
> But to claim that a "dwarf planet" is a "planet" but a "minor planet"
> isn't a "planet" is inconsistent!
>
>
> --
> ----------------------------------------------------------------
> Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
> e-mail: pausch@...
> WWW: http://stjarnhimlen.se/