by Terabithya » Thu Feb 20, 2020 9:56 am
by Farnhamia » Thu Feb 20, 2020 10:11 am
Terabithya wrote:February 18 marked the 90th birthday of the discovery of Pluto, the ninth planet from the Sun. For 76 years it counted as a planet for everyone until a part of the International Astronomical Union (IAU) in 2006 set up a definition of 'planet' and decided that Pluto is no longer one. The reason for that was the discovery of another planet, the tenth planet Eris, called 'Xena' back then. Instead of accepting Eris as the tenth planet, the IAU started to debate on what a planet actually is because they feared that there'd be plenty of new planets, a fear that didn't come true since no other bodies are as big and as massive as Pluto and Eris. There might be an 11th planet far beyond the Kuiper belt so if it exists there would be 11 planets.
The IAU could have easily set up a definition that would include Eris as the tenth planet, but anyway it wasn't necessary to create a definition for 'planet'. There is no definition for 'continent' either. They should just have accepted Eris as the tenth planet and name it accordingly.
Pluto and Eris are planets. I can't describe how wrong, vague and unscientific the 2006 definition is for that would take multiple pages. Please tell me what you think is a planet. Do you consider Pluto a planet and why or why not?
by Terabithya » Thu Feb 20, 2020 11:10 am
Farnhamia wrote:Pluto is a dwarf planet because it hasn't cleared its orbit to the extent required by the IAU (and there are only three requirements). You could very easily look this stuff up and include some of it in the OP. The excuse that you "can't describe how wrong, vague and unscientific the 2006 definition is for that would take multiple pages" is just that, an excuse. But hey, you know better than professional astronomers and astrophysicists and telescope people, so ... sure. I'll stick with the IAU definition. Sorry, Pluto.
by Northwest Slobovia » Thu Feb 20, 2020 11:11 am
Terabithya wrote:the International Astronomical Union (IAU) in 2006 set up a definition of 'planet' and decided that Pluto is no longer one. The reason for that was the discovery of another planet, the tenth planet Eris, called 'Xena' back then.
Terabithya wrote:The IAU could have easily set up a definition that would include Eris as the tenth planet, but anyway it wasn't necessary to create a definition for 'planet'. There is no definition for 'continent' either. They should just have accepted Eris as the tenth planet and name it accordingly.
Terabithya wrote:I can't describe how wrong, vague and unscientific the 2006 definition is for that would take multiple pages.
by Terabithya » Thu Feb 20, 2020 11:12 am
Dogmeat wrote:Meanwhile Ceres is quietly depressed that no one ever even remembers when it got demoted in exactly the same way, and for the same reason.. Poor Ceres.
by Terabithya » Thu Feb 20, 2020 11:15 am
Northwest Slobovia wrote:...add a summary of what you think is wrong with the IAU definition to the OP.
by Northwest Slobovia » Thu Feb 20, 2020 11:16 am
Terabithya wrote:Farnhamia wrote:Pluto is a dwarf planet because it hasn't cleared its orbit to the extent required by the IAU (and there are only three requirements). You could very easily look this stuff up and include some of it in the OP. The excuse that you "can't describe how wrong, vague and unscientific the 2006 definition is for that would take multiple pages" is just that, an excuse. But hey, you know better than professional astronomers and astrophysicists and telescope people, so ... sure. I'll stick with the IAU definition. Sorry, Pluto.
And how would you know if I am an astronomer or not?
Terabithya wrote:How do you define "clearing the orbit"? The IAU makes no concrete requirements. All "dwarf planets" and dwarf planet candidates can be considered to have cleared their hill sphere. On the other hand, no planet, not even Jupiter, "cleared their orbit" so there would actually be no planets at all.
by Northwest Slobovia » Thu Feb 20, 2020 11:18 am
Terabithya wrote:Northwest Slobovia wrote:...add a summary of what you think is wrong with the IAU definition to the OP.
Quaoar and Sedna are not as big and massive as Pluto and Eris. You don't understand it (or don't want to). You could have checked WP for yourself. There probably won't be found bodies as large and massive as Pluto and Eris. But you're free to vote for another option.
by Earth Orbit » Thu Feb 20, 2020 11:19 am
FNS HOMEPAGE | 11/23/2170 | BREAKING: VIOLETIST ATTACKS TAKING PLACE ACROSS FEDERATION, LUNA - STATE OF NATIONAL EMERGENCY DECLARED | 11/23/2170 | FNS HOMEPAGE
by Terabithya » Thu Feb 20, 2020 11:21 am
Northwest Slobovia wrote:Terabithya wrote:
Quaoar and Sedna are not as big and massive as Pluto and Eris. You don't understand it (or don't want to). You could have checked WP for yourself. There probably won't be found bodies as large and massive as Pluto and Eris. But you're free to vote for another option.
I think the IAU definition will do, thanks. And you got a citation for that claim?
by Lord Dominator » Thu Feb 20, 2020 11:23 am
by Terabithya » Thu Feb 20, 2020 11:24 am
Lord Dominator wrote:You're correct that there's no universal definition of continent, but why mention that?
by Estanglia » Thu Feb 20, 2020 11:26 am
Torrocca wrote:"Your honor, it was not mein fault! I didn't order the systematic genocide of millions of people, it was the twenty kilograms of pure-cut Bavarian cocaine that did it!"
by Lord Dominator » Thu Feb 20, 2020 11:29 am
by Catsfern » Thu Feb 20, 2020 11:29 am
by Earth Orbit » Thu Feb 20, 2020 11:29 am
FNS HOMEPAGE | 11/23/2170 | BREAKING: VIOLETIST ATTACKS TAKING PLACE ACROSS FEDERATION, LUNA - STATE OF NATIONAL EMERGENCY DECLARED | 11/23/2170 | FNS HOMEPAGE
by Estanglia » Thu Feb 20, 2020 11:37 am
Catsfern wrote:If dwarf people are still people then dwarf planets are still planets, all im gonna say on this matter.
Torrocca wrote:"Your honor, it was not mein fault! I didn't order the systematic genocide of millions of people, it was the twenty kilograms of pure-cut Bavarian cocaine that did it!"
by Alvecia » Thu Feb 20, 2020 11:47 am
Terabithya wrote:Farnhamia wrote:Pluto is a dwarf planet because it hasn't cleared its orbit to the extent required by the IAU (and there are only three requirements). You could very easily look this stuff up and include some of it in the OP. The excuse that you "can't describe how wrong, vague and unscientific the 2006 definition is for that would take multiple pages" is just that, an excuse. But hey, you know better than professional astronomers and astrophysicists and telescope people, so ... sure. I'll stick with the IAU definition. Sorry, Pluto.
And how would you know if I am an astronomer or not? And what about yourself? How do you define "clearing the orbit"? The IAU makes no concrete requirements. All "dwarf planets" and dwarf planet candidates can be considered to have cleared their hill sphere. On the other hand, no planet, not even Jupiter, "cleared their orbit" so there would actually be no planets at all. But it's not really the IAU's definition because about 4.2% of the IAU voted for the 2006 definition while other IAU astronomers were gone.
In the end stages of planet formation, a planet (as so defined) will have "cleared the neighbourhood" of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its natural satellites or those otherwise under its gravitational influence. A large body that meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which is constrained in its orbit by the gravity of Neptune and shares its orbital neighbourhood with many Kuiper belt objects. The IAU's definition does not attach specific numbers or equations to this term, but all the IAU-recognised planets have cleared their neighbourhoods to a much greater extent (by orders of magnitude) than any dwarf planet, or any candidate for dwarf planet.
by Terabithya » Thu Feb 20, 2020 11:52 am
Alvecia wrote: In the end stages of planet formation, a planet (as so defined) will have "cleared the neighbourhood" of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its natural satellites or those otherwise under its gravitational influence. A large body that meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which is constrained in its orbit by the gravity of Neptune and shares its orbital neighbourhood with many Kuiper belt objects. The IAU's definition does not attach specific numbers or equations to this term, but all the IAU-recognised planets have cleared their neighbourhoods to a much greater extent (by orders of magnitude) than any dwarf planet, or any candidate for dwarf planet.
by Catsfern » Thu Feb 20, 2020 11:55 am
by Estanglia » Thu Feb 20, 2020 11:56 am
Torrocca wrote:"Your honor, it was not mein fault! I didn't order the systematic genocide of millions of people, it was the twenty kilograms of pure-cut Bavarian cocaine that did it!"
by Catsfern » Thu Feb 20, 2020 12:52 pm
by Estanglia » Thu Feb 20, 2020 1:42 pm
Torrocca wrote:"Your honor, it was not mein fault! I didn't order the systematic genocide of millions of people, it was the twenty kilograms of pure-cut Bavarian cocaine that did it!"
by Alvecia » Thu Feb 20, 2020 1:49 pm
Terabithya wrote:Alvecia wrote: In the end stages of planet formation, a planet (as so defined) will have "cleared the neighbourhood" of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its natural satellites or those otherwise under its gravitational influence. A large body that meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which is constrained in its orbit by the gravity of Neptune and shares its orbital neighbourhood with many Kuiper belt objects. The IAU's definition does not attach specific numbers or equations to this term, but all the IAU-recognised planets have cleared their neighbourhoods to a much greater extent (by orders of magnitude) than any dwarf planet, or any candidate for dwarf planet.
The 2006 definition doesn't get any concrete. And what you described in your citation would have to ban Pluto, but not Eris, from the planets.
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