Definition of a planet

"Chris Jones" wrote in message
...
(Henry Spencer) writes:

In article ,
Thomas A. Fine wrote:
A definition of planet that results in Jupiter, Earth, Mercury, Pluto,
"Xena", and Ceres all being called planets is not useful to
scientists...

Well, for a good bit of the 19th century, people thought otherwise...
The
first four asteroids found were listed as planets for quite a while. (It
happened that those four were found in fast succession, and then it was
several decades before the fifth was noticed.)

I think a useful definition of planet could take into account orbital
inclination and eccentricity as well as size. Personally, I'd set the
values so Pluto, Xena, and Mercury(!) would fail the test and the other
8 bodies considered planets (Venus through Neptune) would pass.

Why not set the standard so that Earth fails the test? My personal
inclination is to count both Ceres and Xena as planets. We have already
begun detecting planets around other stars. As our technology improves and
we can detect smaller objects, we will most likely end up with an objective
definition of the word planet. I think that the standard will be based on
mass or size or both. The mass chosen will be one that almost always
results in a spherical body. We seem to have emotional attachments to
bodies within our solar system. Initially, that won't be true for bodies
elsewhere.

Martian moons raise the question of how big does an object have to be to
qualify as a moon?

Phineas T Puddleduck wrote:
Not only do I not know, I don't care. Its inconsequential...
Thanks for being honest, as well as your usual inconsequential self.
-
Brad Guth

Mike Rhino ) wrote:
: "Chris Jones" wrote in message
: ...
: (Henry Spencer) writes:
:
: In article ,
: Thomas A. Fine wrote:
: A definition of planet that results in Jupiter, Earth, Mercury, Pluto,
: "Xena", and Ceres all being called planets is not useful to
: scientists...
:
: Well, for a good bit of the 19th century, people thought otherwise...
: The
: first four asteroids found were listed as planets for quite a while. (It
: happened that those four were found in fast succession, and then it was
: several decades before the fifth was noticed.)
:
: I think a useful definition of planet could take into account orbital
: inclination and eccentricity as well as size. Personally, I'd set the
: values so Pluto, Xena, and Mercury(!) would fail the test and the other
: 8 bodies considered planets (Venus through Neptune) would pass.

: Why not set the standard so that Earth fails the test? My personal
: inclination is to count both Ceres and Xena as planets. We have already
: begun detecting planets around other stars. As our technology improves and
: we can detect smaller objects, we will most likely end up with an objective
: definition of the word planet. I think that the standard will be based on
: mass or size or both. The mass chosen will be one that almost always
: results in a spherical body. We seem to have emotional attachments to
: bodies within our solar system. Initially, that won't be true for bodies
: elsewhere.

There is also the aspect of tradition. M51, NGC 6822 and the like are fine
for science, cataloging and use within a computer but people prefer names
that they can identify with.

: Martian moons raise the question of how big does an object have to be to
: qualify as a moon?


Likewise, does Saturn's rings.

Eric Chomko,
Did you ever accomplish the 'once upon a time' icy proto-moon bouncing
off of Earth thing?
-
Brad Guth

David Knisely wrote:
Phineas T Puddleduck wrote:

Now you've gone back to nonsense.....

Guth is not worth your responses. Killfile him and all will be well.
Clear skies to you.
We see that you're still nothing but a topic/author stalking wizard of
a mainstream status quo born-again liar, therefore an intellectual
bigot, a pagan heathen and a Third Reich collaborator, as well as being
anti-ET as you can get. Keep up the good work on behalf of the likes
of your resident LLPOF warlord(GW Bush) and of your mutual Skull and
Bones cult.

Too bad that our once upon a time icy proto-moon and of it salty
remainder that's so gamma and hard-X-ray prone can't be honestly
discussed because of incest cloned borgs like yourself that would much
rather remain fully brown-nosed than the least bit honest, much less
open box minded.

Too bad that the extremely much older than Earth existence of Mars is
such an ongoing drain on our talents and resources, while the fairly
newish Venus is being kept sequestered.
-
Brad Guth

Brad Guth wrote:
Eric Chomko,
Did you ever accomplish the 'once upon a time' icy proto-moon bouncing
off of Earth thing?
-
Brad Guth

I guess our "Eric Chomko" is once again dumbfounded.

Too bad that our once upon a time icy proto-moon and of it salty
remainder that's so hard Van Allen like and thus having become so gosh
darn gamma and hard-X-ray prone, as such can't be honestly discussed
because of all the incest cloned and two-faced borgs like yourself that
would much rather remain as fully brown-nosed than the least bit
honest, much less open box minded.

Too bad that the much older than Earth existence of Mars is such an
ongoing drain on our talents and resources, while the fairly newish and
extremely nearby Venus that's so nicely geothermally toasty (like early
Earth) is being kept sequestered.
-
Brad Guth

Brad Guth ) wrote:
: Eric Chomko,
: Did you ever accomplish the 'once upon a time' icy proto-moon bouncing
: off of Earth thing?

No, because I really don't belief it. I mean there is no evidence that the
Earth captured a KBO. KBOs that get within 1 AU of the sun would most
likely be comets and I don't believe that the Moon was ever a comet before
settling down to its current state. The evidence better supports (Occum's
Razor, of which you seem challenged) the Earth and the Moon being
co-creations of the same basic event.

Eric

: -
: Brad Guth

Brad Guth ) wrote:

: Brad Guth wrote:
: Eric Chomko,
: Did you ever accomplish the 'once upon a time' icy proto-moon bouncing
: off of Earth thing?
: -
: Brad Guth

: I guess our "Eric Chomko" is once again dumbfounded.

No, I responded. Did you give me a chance?

: Too bad that our once upon a time icy proto-moon and of it salty
: remainder that's so hard Van Allen like and thus having become so gosh
: darn gamma and hard-X-ray prone, as such can't be honestly discussed
: because of all the incest cloned and two-faced borgs like yourself that
: would much rather remain as fully brown-nosed than the least bit
: honest, much less open box minded.

No, I think I pegged you well as being Occum's razor-challenged, as you
tend to want more assumptions and like to increase your premises.

: Too bad that the much older than Earth existence of Mars is such an
: ongoing drain on our talents and resources, while the fairly newish and
: extremely nearby Venus that's so nicely geothermally toasty (like early
: Earth) is being kept sequestered.

Venus sequesters itself due to the ongoing planetological chaos of 450 C
degrees and 90 bars atmospheric pressure at the surface.

Eric

: -
: Brad Guth

steve wrote:

With this set to be finalised fairly soon in September 2006 I think it
is essential that a few sensible parameters are added.

1) A body in orbit around a star.

2) Size must be larger than Pluto ( or another agreed specified size
and mass) to give a minimum size UNLESS extra-terrestial life is found
on the planet when a much smaller size would be allowed.

3) If the size of a moon is similar (to a stated percentage e.g. 80%)
to the larger body in its group it to can be called a planet if it
meets (1) and (2)
Thus it is possibe to have binary planets.

4) It would probably be necessary to specify a maximum distance from
the star in which the planet is in orbit to dis-allow wandering rocks.

Essential to whom? You have just beaten Daniel J. Min in the Idiot of
the Aeon competition.

Davoud

Eric Chomko wrote:
Brad Guth ) wrote:
: Did you ever accomplish the 'once upon a time' icy proto-moon bouncing
: off of Earth thing?

No, because I really don't belief it. I mean there is no evidence that the
Earth captured a KBO. KBOs that get within 1 AU of the sun would most
likely be comets and I don't believe that the Moon was ever a comet before
settling down to its current state. The evidence better supports (Occum's
Razor, of which you seem challenged) the Earth and the Moon being
co-creations of the same basic event.

Eric

What's with your having to believe, especially if the regular laws of
physics/astrophysics as well as that of cosmology and planetology
stipulates that it's entirely possible, as having been continually
recorded and fully accepted as having unavoidably transpired elsewhere?

Or don't you believe that we're existing as a solar system that's still
associated and/or in orbit about anything other?

If so, can you explain how it is that we're the one and only such
independent solar system (somewhat wussy mass at that) that's been
drifting free of all other gravity and energy influnces?

There's certainly no hard-science or that of any other believable
evidence that our rather unusually salty moon is made of Earth. Lots
of naturally deposited moon rocks available on Earth that'll more than
tend to prove (via lead dating and other chemical/element composition
means), that's the truth and nothing but the truth.

I also "don't believe that the Moon was ever a comet before settling
down to its current state", as it may have simply arrived at a much
slower velocity along with it's own planet, namely Venus, as having
merged from the same or at least sufficiently similar rotational field,
and having unavoidably bumped into us (at least something icy-moon
sized had delivered such a glancing blow up North). Just like there's
no good rime nor reason(s) why Mars is a little older than Earth, but
then it obviously is (it sure as hell isn't and less older than Earth).

It's getting a little tough being such a multi-faced wizard, isn't it?

I obviously don't believe in the one and only God like singular event,
whereas we've seen all sorts of near misses and unavoidable impacts or
significant mergers that pretty much proves there were multiple events
and even cycles of such events within events, which obviously can't
happen if all is starting out from and forever expanding from a given
singular point of creation, and I do believe that's exactly what
Einstein thought was the case, that such a singular event is unlikely
if not impossible.
-
Brad Guth