David Player skrev:

>
>
> I like your rationale Bill.
>
> In fact, I still don't understand what all the fuss was about anyway.
> When the IAU identifies Pluto it is still called "planet" but with the
> adjective "minor" preceeding (in English). The point is, it is not a
> star, not a planetoid,

FYI: a "minor planet" is the same thing as a "planetoid".

> not a comet,

I wouldn't be so sure about that. Like the comets, Pluto is most likely an icy
world. And if Pluto somehow could be brought to the inner parts of our solar
system, it could easily become the grandest of all comets we've ever seen.

> etc, etc, etc, but is a planet.
>
> There are rocky planets, gas giants, minor planets
>
> Such a fuss about so little.
>
> david

............................

> Oh drat !! I meant DWARF Planet, not minor.... 3 weeks on the road and
> my eyes are dim.
>
> david

Acutally, Pluto is nowadays officially minor planet number 134340. So you could
as well call it minor planet (134340) Pluto.

And that means if you load the minor planets up to number 134340 into Guide,
then Pluto will appear twice: as a major planet, and as minor planet no 134340.

When the number of numbered minor planets started to approach 10000, Brian
Marsden suggested that Pluto should receive minor planet number 10000. However,
that suggestion was then turned down. As a result, Pluto is now minor planet
number 134340 instead of number 10000.

Regarding possible double classifications: Pluto is not unique here. For
instance Chiron is both minor planet (2060) Chiron and periodic comet
95P/Chiron. Several other small solar system bodies are also doubly classified
as both comets and minor planets.

In a way, Pluto now has quadruple classification: according to the new IAU
definition, Pluto is a "dwarf planet" which, according to the IAU, is not a
"planet". A lot of people still want to count Pluto among the major planets
though, and will probably continue to do so for some time. Third, Pluto is
officially minor planet number 134340. And fourth, Pluto is an icy world which
showed a thin atmosphere when near perihelion around 1989. This is a cometary
property of Pluto and therefore some people consider Pluto to be a comet, much
grander and larger than most comets - IMO these people do have a point.

Perhaps we could all just agree that Pluto is a border case, which straddles
several categories of solar system objects. And that it also has a history of
having been considered to be a major planet for the first five decades of our
knowledge of Pluto's existence - not until the discovery of Charon did we learn
how small Pluto really is.


--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch@...
WWW: http://stjarnhimlen.se/