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Experts meet to decide Pluto fate, Finally we'll know what a 'planet' is...
ngunn
post Aug 16 2006, 10:31 AM
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I wonder what happens if the mutual orbits are eccentric and the barycentre moves in and out of the larger body every 'month'?
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djellison
post Aug 16 2006, 10:39 AM
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And just for good measure, an article about a backward polarity sun spot today describes sun spots as being 'planet sized'

PLANET SIZED

What the hell does that mean smile.gif

Doug
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ugordan
post Aug 16 2006, 10:50 AM
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QUOTE (ngunn @ Aug 16 2006, 11:31 AM) *
I wonder what happens if the mutual orbits are eccentric and the barycentre moves in and out of the larger body every 'month'?

Perhaps an "average" barycenter point can be taken as measure in that case. Say circularizing the orbits, leaving the orbital periods constant?


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paxdan
post Aug 16 2006, 11:06 AM
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QUOTE (djellison @ Aug 16 2006, 11:39 AM) *
PLANET SIZED

What the hell does that mean smile.gif


Pah! that's an easy one: 950 to 142984 km.
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Guest_JamesFox_*
post Aug 16 2006, 11:07 AM
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Personally, I have to admit that I feel rather uneasy about this proposal. People are liable to reject it on unscientific grounds because it provides 'too many planets'. Also, why do they mention only three planet candidates to the news, while treating other qualifying objects in a a separate, not-mentioned to the news category? I've seen quite alot of opposition already.

I think a slightly more acceptable definition would stress the difference between the 'dwarf planets' and the 'eight classical planets', thus allowing those who are so inclined to ignore the dwarf planets, while the inclusivists would include the dwarf planets.
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David
post Aug 16 2006, 11:15 AM
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QUOTE (JamesFox @ Aug 16 2006, 11:07 AM) *
Also, why do they mention only three planet candidates to the news, while treating other qualifying objects in a a separate, not-mentioned to the news category? I've seen quite alot of opposition already.


My recommendation to anyone who has to talk to the press about this is:

1. Design a wallet-sized card that lists all the objects in the Solar System that will be labelled "planets" under the new definition: don't go overboard, but include name and a couple of basic facts, like diameter and "distance from the Sun".

2. Print out several hundred copies of this card.

3. Hand it out/ e-mail it to everybody who asks (and everybody who doesn't).
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Guest_JamesFox_*
post Aug 16 2006, 11:25 AM
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QUOTE (David @ Aug 16 2006, 07:15 AM) *
1. Design a wallet-sized card that lists all the objects in the Solar System that will be labelled "planets" under the new definition: don't go overboard, but include name and a couple of basic facts, like diameter and "distance from the Sun".


The problem with this is that the sizes of many objects are currently very uncertain. How big is Orcus, Sedna, or Varuna? Estimates have been made, and some objects are certainly big enough despite uncertainties in size, but I'm not sure how the public will take to such probably long-lasting indeterminate statuses. It will take years before even the objects currently known have thier sizes determined accurately enough.
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David
post Aug 16 2006, 11:34 AM
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QUOTE (JamesFox @ Aug 16 2006, 11:25 AM) *
The problem with this is that the sizes of many objects are currently very uncertain.


That's why God invented the asterisk.
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Ames
post Aug 16 2006, 11:40 AM
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QUOTE (JamesFox @ Aug 16 2006, 12:07 PM) *
I think a slightly more acceptable definition would stress the difference between the 'dwarf planets' and the 'eight classical planets', thus allowing those who are so inclined to ignore the dwarf planets, while the inclusivists would include the dwarf planets.


That sounds sensible to me and something that the public could understand.
But they are going to have a field day with barycenter...
"What? Barry Sentor? - never heard of him!"

I think Pluto should be a planet(maybe dwarf maybe -oid) with a large(in comparison) moon that just happens to be large enough to set the "Barry Sentor" above Plutos' surface. Why a double planet?

We either need to make it a simple definition that the Public will understand and accept, or a rigorous (and useful) definition for scientists. Otherwise I fear that the Public may just ignore the more difficult concepts and revert to the old definition of the solar-system and the scientsts will be off in their own word of planetoids, plutinos, barrycenters...



Nick
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Ames
post Aug 16 2006, 11:44 AM
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QUOTE (Ames @ Aug 16 2006, 12:40 PM) *
That sounds sensible to me and something that the public could understand.
But they are going to have a field day with barycenter...
"What? Barry Sentor? - never heard of him!"

I think Pluto should be a planet(maybe dwarf maybe -oid) with a large(in comparison) moon that just happens to be large enough to set the "Barry Sentor" above Plutos' surface. Why a double planet?

We either need to make it a simple definition that the Public will understand and accept, or a rigorous (and useful) definition for scientists. Otherwise I fear that the Public may just ignore the more difficult concepts and revert to the old definition of the solar-system and the scientsts will be off in their own word of planetoids, plutinos, barrycenters...
Nick



Actually Barry Senter huh.gif

www.barrysenterdesign.com

Hmmm! biggrin.gif

Nick
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David
post Aug 16 2006, 11:57 AM
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Does "double planet" imply a single entity that happens to consist of two units, or two planets that happen to be revolving around each other?

In other words, can one say "Pluto-Charon is a planet"?
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MichaelT
post Aug 16 2006, 12:07 PM
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QUOTE (David @ Aug 16 2006, 11:57 AM) *
Does "double planet" imply a single entity that happens to consist of two units, or two planets that happen to be revolving around each other?

In other words, can one say "Pluto-Charon is a planet"?

I don't think so. The IAU release explicitely states 12 planets including Charon. If the double planet was counted as one entity, there'd be only 11. So they are two planets revolving around each other.

Michael
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ugordan
post Aug 16 2006, 12:25 PM
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QUOTE (MichaelT @ Aug 16 2006, 01:07 PM) *
So they are two planets revolving around each other.

Hmm... We seem to be running in circles here, so to speak. Didn't they say a body needs to orbit the Sun, not another body, in order to be classified as a planet? If so, how can Charon (and for that matter Pluto as well!) be a planet?


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paxdan
post Aug 16 2006, 12:41 PM
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QUOTE (ugordan @ Aug 16 2006, 01:25 PM) *
Hmm... We seem to be running in circles here, so to speak. Didn't they say a body needs to orbit the Sun, not another body, in order to be classified as a planet? If so, how can Charon (and for that matter Pluto as well!) be a planet?

Barry Sentor would like a word
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ngunn
post Aug 16 2006, 12:44 PM
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QUOTE (dvandorn @ Aug 16 2006, 05:23 AM) *
So, is the new nursery-rhyme mnemonic for the planets going to go something lik this?

"My Very Educated Mother, Catherine, Just Served Us Nine Pickled, Spicy Xylophones."

biggrin.gif

-the other Doug


How about: Many Vexed Experts Make Confusing Judgment So Us Normal People Say 'XXXX'
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