Experts meet to decide Pluto fate, Finally we'll know what a 'planet' is... |
Experts meet to decide Pluto fate, Finally we'll know what a 'planet' is... |
Aug 14 2006, 06:06 AM
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#1
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Member Group: Members Posts: 295 Joined: 2-March 04 From: Central California Member No.: 45 |
-------------------- Eric P / MizarKey
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Guest_JamesFox_* |
Aug 16 2006, 11:07 AM
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#2
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Guests |
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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Aug 16 2006, 11:40 AM
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#3
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Member Group: Members Posts: 147 Joined: 30-June 05 From: Bristol, UK Member No.: 423 |
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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Aug 16 2006, 11:44 AM
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#4
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Member Group: Members Posts: 147 Joined: 30-June 05 From: Bristol, UK Member No.: 423 |
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 www.barrysenterdesign.com Hmmm! Nick |
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Aug 16 2006, 11:57 AM
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#5
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Member Group: Members Posts: 809 Joined: 11-March 04 Member No.: 56 |
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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Aug 16 2006, 12:07 PM
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#6
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Member Group: Members Posts: 156 Joined: 18-March 05 From: Germany Member No.: 211 |
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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Aug 16 2006, 12:25 PM
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#7
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
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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Aug 16 2006, 12:57 PM
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#8
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Member Group: Members Posts: 529 Joined: 19-February 05 Member No.: 173 |
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? Owing to its high mass relative to Pluto, Pluto-Charon's barycenter is in free space, which means Charon is technically in orbit about the Sun, not Pluto. This is not a debatable fact, it's just the way the dynamics works. |
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Aug 16 2006, 01:29 PM
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#9
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Member Group: Members Posts: 809 Joined: 11-March 04 Member No.: 56 |
Owing to its high mass relative to Pluto, Pluto-Charon's barycenter is in free space, which means Charon is technically in orbit about the Sun, not Pluto. This is not a debatable fact, it's just the way the dynamics works. Of course Charon is in orbit around the Sun, but then so is Earth's Moon. Here's another way to look at it: if you sketch the ellipse of Charon's orbit about the Pluto-Charon barycentre, Pluto is always within Charon's orbit; if you sketch the ellipse of Pluto's orbit, Charon is never found inside it: Pluto's orbit is so close to the barycentre that saying that Charon doesn't orbit Pluto (but rather a bit of empty space close to Pluto), though technically correct, seems whimsical, sort of like denying that Jupiter revolves around the Sun. |
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