> Thank you very much. The earlier post discussed the fuzzy semantics of
> the words "planet" and "moon". By naming the top 15 objects in the solar
> system, we find that one of the "planets" is not on the list, but 6 of the
> "moons" are. The discovery of a Kuiper Belt object larger than Pluto
> would further muddy the semantic water with respect to the words planet,
> moon, and asteroid.
>

In later times, there has been a tendency to revise the definition of
"planet". For instance, some say that "planets" should be defined as bodies
that orbit the Sun and have the right composition and enough mass to present
a spherical shape. In that definition, our Solar System has well more than
*ten* planets, because Ceres would be a planet too, as well as many of the
KBOs. Other bodies that are large-enough-to-be-spherical but don't orbit the
Sun (namely, the moons and "rogue planets") would not be planets but would
be "planetary bodies" as well.

Personally, I think that "planetary body" is too long and I prefer to call
this class of objects "orbs". It is a word for "spheres" that is not very
usual and it is very short. (And I am ashamed to confess that I borrowed
that term from a class of wacky people in my country, namely Brazilian
ufologists. They are used to refers to the supposed aliens as "visitors from
other orbs"... ;-)

Other astronomers think that the classification "planet" is completely
devoid of scientific utility, and prefer to divide the bodies in the Solar
System in the following "clusters": the Sun; the Gas Giants; the rocky
worlds; the asteroids; and the KPOs. (Pluto is a KPO in this
classification.) Well, of course even this classification is plagued by
fuzzy boundaries... Everyone knows that the border between comets and
asteroids is blurry; also, were the icy orbs orbiting the gas giants enter
in this classification?

> Many school children can rattle off the sequence of the nine planets, but
> very few know the top 15 or top 17 objects in the solar system, much less
> their ordering. This item is, I think, of some concern to ssi_list ---
> many of us believe that there is a natural tendency in the populace at
> large to romanticize "planets", a tendency that is not particularly
> favorable to the goals of SSI.
>

Well, decades of scifi shows were people have to go to Planet Keelix or
something like that to change the warpcore of their starships had their
deleterious effects...

>
> Ron
> *****
[snikt]

Lucio

On my website, I've written a classification scheme for solar system
objects. I want to make it as perfect as possible, so please send me
any possible scientific criticism.

My website: http://www.geocities.com/mad_scientist2064/
Classification: http://www.geocities.com/mad_scientist2064/sso.htm

>
> > Thank you very much. The earlier post discussed the fuzzy
semantics of
> > the words "planet" and "moon". By naming the top 15 objects in
the solar
> > system, we find that one of the "planets" is not on the list, but
6 of the
> > "moons" are. The discovery of a Kuiper Belt object larger than
Pluto
> > would further muddy the semantic water with respect to the words
planet,
> > moon, and asteroid.
> >
> In later times, there has been a tendency to revise the definition
of
> "planet". For instance, some say that "planets" should be defined
as bodies
> that orbit the Sun and have the right composition and enough mass
to present
> a spherical shape. In that definition, our Solar System has well
more than
> *ten* planets, because Ceres would be a planet too, as well as many
of the
> KBOs. Other bodies that are large-enough-to-be-spherical but don't
orbit the
> Sun (namely, the moons and "rogue planets") would not be planets
but would
> be "planetary bodies" as well.
>
> Personally, I think that "planetary body" is too long and I prefer
to call
> this class of objects "orbs". It is a word for "spheres" that is
not very
> usual and it is very short. (And I am ashamed to confess that I
borrowed
> that term from a class of wacky people in my country, namely
Brazilian
> ufologists. They are used to refers to the supposed aliens
as "visitors from
> other orbs"... ;-)
>
> Other astronomers think that the classification "planet" is
completely
> devoid of scientific utility, and prefer to divide the bodies in
the Solar
> System in the following "clusters": the Sun; the Gas Giants; the
rocky
> worlds; the asteroids; and the KPOs. (Pluto is a KPO in this
> classification.) Well, of course even this classification is
plagued by
> fuzzy boundaries... Everyone knows that the border between comets
and
> asteroids is blurry; also, were the icy orbs orbiting the gas
giants enter
> in this classification?
>
> > Many school children can rattle off the sequence of the nine
planets, but
> > very few know the top 15 or top 17 objects in the solar system,
much less
> > their ordering. This item is, I think, of some concern to
ssi_list ---
> > many of us believe that there is a natural tendency in the
populace at
> > large to romanticize "planets", a tendency that is not
particularly
> > favorable to the goals of SSI.
> >
> Well, decades of scifi shows were people have to go to Planet
Keelix or
> something like that to change the warpcore of their starships had
their

On my website, I've written a classification scheme for solar system
objects. I want to make it as perfect as possible, so please send me
any possible scientific criticism.

My website: http://www.geocities.com/mad_scientist2064/
Classification: http://www.geocities.com/mad_scientist2064/sso.htm

I think that your classification makes a lot of sense! I would just make two
alterations:

- I would classify Io as a Selene. Io is basically an all-rocky world with
no atmosphere, and it looks so different from the Moon and from Mercury just
because it has that bunch of volcanoes spitting debris. But the volcanoes
are not exactly "intrinsic" to Io - they are just a side effect of Jupiter's
massive tides. Maybe Io would look nearly identical to Mercury if it were
located in a place with no gravitational stress.

- I'm not sure if Titan should be put with the other Cronus. First, it has
an atmosphere; second, according to infrared images taken in recent years,
it has a lot of "dark" and "light" areas that resemble continents and oceans
that in fact *may be* continents and oceans - made of liquid and frozen
methane and stuff like that ;-). So, I think that Titan should have its own
category.

- Finally, the 400 Km of diameter limit is kind of arbitrary. A rocky object
that size could still be very "edgy", while an icy object would be nearly
spherical. I think that the criterion should be sphericity, and not size.
(But maybe I'm way too contaminated by my idea of "orb". ;-)

Lucio Coelho

Thanks for the suggestions, and the compliment. :-)

>
> On my website, I've written a classification scheme for solar system
> objects. I want to make it as perfect as possible, so please send
me
> any possible scientific criticism.
>
> My website: http://www.geocities.com/mad_scientist2064/
> Classification: http://www.geocities.com/mad_scientist2064/sso.htm
>
> I think that your classification makes a lot of sense! I would just
make two
> alterations:
>
> - I would classify Io as a Selene. Io is basically an all-rocky
world with
> no atmosphere, and it looks so different from the Moon and from
Mercury just
> because it has that bunch of volcanoes spitting debris. But the
volcanoes
> are not exactly "intrinsic" to Io - they are just a side effect of
Jupiter's
> massive tides. Maybe Io would look nearly identical to Mercury if
it were
> located in a place with no gravitational stress.
>
> - I'm not sure if Titan should be put with the other Cronus. First,
it has
> an atmosphere; second, according to infrared images taken in recent
years,
> it has a lot of "dark" and "light" areas that resemble continents
and oceans
> that in fact *may be* continents and oceans - made of liquid and
frozen
> methane and stuff like that ;-). So, I think that Titan should have
its own
> category.
>
> - Finally, the 400 Km of diameter limit is kind of arbitrary. A
rocky object
> that size could still be very "edgy", while an icy object would be
nearly
> spherical. I think that the criterion should be sphericity, and not
size.