Slashdot Mirror
'Yes, Pluto Is a Planet' (sfgate.com)
schwit1 quotes a Washington Post perspective piece by the authors of a new book about Pluto:
The process for redefining planet was deeply flawed and widely criticized even by those who accepted the outcome. At the 2006 IAU conference, which was held in Prague, the few scientists remaining at the very end of the week-long meeting (less than 4 percent of the world's astronomers and even a smaller percentage of the world's planetary scientists) ratified a hastily drawn definition that contains obvious flaws. For one thing, it defines a planet as an object orbiting around our sun -- thereby disqualifying the planets around other stars, ignoring the exoplanet revolution, and decreeing that essentially all the planets in the universe are not, in fact, planets.
Even within our solar system, the IAU scientists defined "planet" in a strange way, declaring that if an orbiting world has "cleared its zone," or thrown its weight around enough to eject all other nearby objects, it is a planet. Otherwise it is not. This criterion is imprecise and leaves many borderline cases, but what's worse is that they chose a definition that discounts the actual physical properties of a potential planet, electing instead to define "planet" in terms of the other objects that are -- or are not -- orbiting nearby. This leads to many bizarre and absurd conclusions. For example, it would mean that Earth was not a planet for its first 500 million years of history, because it orbited among a swarm of debris until that time, and also that if you took Earth today and moved it somewhere else, say out to the asteroid belt, it would cease being a planet.
To add insult to injury, they amended their convoluted definition with the vindictive and linguistically paradoxical statement that "a dwarf planet is not a planet." This seemingly served no purpose but to satisfy those motivated by a desire -- for whatever reason -- to ensure that Pluto was "demoted" by the new definition. By and large, astronomers ignore the new definition of "planet" every time they discuss all of the exciting discoveries of planets orbiting other stars.
Even within our solar system, the IAU scientists defined "planet" in a strange way, declaring that if an orbiting world has "cleared its zone," or thrown its weight around enough to eject all other nearby objects, it is a planet. Otherwise it is not. This criterion is imprecise and leaves many borderline cases, but what's worse is that they chose a definition that discounts the actual physical properties of a potential planet, electing instead to define "planet" in terms of the other objects that are -- or are not -- orbiting nearby. This leads to many bizarre and absurd conclusions. For example, it would mean that Earth was not a planet for its first 500 million years of history, because it orbited among a swarm of debris until that time, and also that if you took Earth today and moved it somewhere else, say out to the asteroid belt, it would cease being a planet.
To add insult to injury, they amended their convoluted definition with the vindictive and linguistically paradoxical statement that "a dwarf planet is not a planet." This seemingly served no purpose but to satisfy those motivated by a desire -- for whatever reason -- to ensure that Pluto was "demoted" by the new definition. By and large, astronomers ignore the new definition of "planet" every time they discuss all of the exciting discoveries of planets orbiting other stars.
There is almost only one country that does not use the SI meter system and there is almost only one country that thinks pluto is a planet. USA is sometime ridiculous in its fights. All the rest of the world knows why USA does not want the title of "planet" to be removed from Pluto ... ;-)
(Spoiler alert : It is the only planet of the solar system discovered by a US citizen as far as we know)
If you plan to call it a planet, what about Eris or Makemake, etc ? Where do we stop ?
That is why there were rules defined to set the limit. As a consequence of those rules, Pluto is no more a planet of the solar system but a dwarf planet such as Eris or Makemake ... If you don't like it you can try to change the classification in the next conference. But doing so, we might end up with tens or hundreds of new "planets" because of the removal of rule 3 that block Pluto from beeing a planet. I don't think pupils from the world would be glad of this change when they will have to learn a lot more of planets because of a USA caprice :P
Problem #1: Authors complain that the definition of "planet" doesn't include exoplanets (because they don't orbit the Sun)..
Solution: Change definition to include other stars or say that the particular star doesn't matter if the other criteria are met.
Problem #2: Authors complain that the criterion that a planet must "clear its orbit" is imprecise and is dependent on other objects.
Solution: None needed. Let the IAU define the border cases. As for being dependent on other objects, the point is that for an object to be a planet, it must utterly dominate its orbit, leaving nothing significant.
Problem #3: By the IAU definition, Earth was not a planet for the first 500 MYears of its existence, because it hadn't yet cleared its orbit. Authors call this "bizarre and absurd".
Solution: Why is this a problem? There was no guarantee that the Earth was going to survive as a planet. Another Theia-like impact could have ended it.
Problem #4: It is a linguistic paradox (and vindictive to boot) to say "a dwarf planet is not a planet."
Solution: So what? A guinea pig is not a pig. Spotted dick is not a dick. Etc.
It never ceases to amaze me how emotional the "Pluto is a planet" people are and how the MSM gives these people much more publicity then they deserve. In the immortal words of Neil DeGrasse tyson, "Get over it!"
Hopelessly pedantic since 1963.