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posted by martyb on Saturday September 08 2018, @10:24AM   Printer-friendly
from the there-goes-the-neighborhood dept.

Pluto a Planet? New Research from UCF Suggests Yes

The reason Pluto lost its planet status is not valid, according to new research from the University of Central Florida in Orlando. In 2006, the International Astronomical Union, a global group of astronomy experts, established a definition of a planet that required it to "clear" its orbit, or in other words, be the largest gravitational force in its orbit. [...] [Philip] Metzger, who is lead author on the study, reviewed scientific literature from the past 200 years and found only one publication -- from 1802 -- that used the clearing-orbit requirement to classify planets, and it was based on since-disproven reasoning.

[...] The planetary scientist said that the literature review showed that the real division between planets and other celestial bodies, such as asteroids, occurred in the early 1950s when Gerard Kuiper published a paper that made the distinction based on how they were formed. However, even this reason is no longer considered a factor that determines if a celestial body is a planet, Metzger said.

[...] Instead, Metzger recommends classifying a planet based on if it is large enough that its gravity allows it to become spherical in shape. "And that's not just an arbitrary definition, Metzger said. "It turns out this is an important milestone in the evolution of a planetary body, because apparently when it happens, it initiates active geology in the body." Pluto, for instance, has an underground ocean, a multilayer atmosphere, organic compounds, evidence of ancient lakes and multiple moons, he said. "It's more dynamic and alive than Mars," Metzger said. "The only planet that has more complex geology is the Earth."

Planet Ceres, please.

The Reclassification of Asteroids from Planets to Non-Planets (DOI: 10.1016/j.icarus.2018.08.026) (DX)

Related: Pluto May Regain Status as Planet
Earth is a "Dwarf Planet" Because it has not Cleared its Orbit


Original Submission

 
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  • (Score: 4, Insightful) by AthanasiusKircher on Saturday September 08 2018, @01:07PM (2 children)

    by AthanasiusKircher (5291) on Saturday September 08 2018, @01:07PM (#732178) Journal

    I'm frankly a bit tired of this continuous "debate." Is there a way to tag the submitted article as "flamebait"? Because that's effectively what it is.

    From the abstract of the original research article:

    We suggest attempts to build consensus around planetary taxonomy not rely on the non-scientific process of voting, but rather through precedent set in scientific literature and discourse, by which perspectives evolve with additional observations and information, just as they did in the case of asteroids.

    These are just fighting words. And this research not based on anything better. What did they do? They reviewed astronomical literature for the past couple hundred years. And they discovered that scientists of the past might have valued other things! Wow! Amazing! Who'd have thought?!

    Basically, this "research" is just an appeal to authority, coupled with a sort of "etymological fallacy" -- i.e., "Great people of the past thought THIS way, and THIS is where our definition of 'planet' meant then!" By that standard, why not just go back to the ancient Greeks? Forget about a measly two hundred years. For two THOUSAND years the scientific standard for a planet was based on its meaning (etymologically) as a "wanderer" in the heavens, and there were precisely FIVE bodies that qualified: Mercury, Venus, Mars, Jupiter, and Saturn. The scientific standard back then was "visible to the naked eye," which isn't a great criterion, but it was based on the available and understood science of the time.

    Why ignore the scientific literature from antiquity through the year 1800?? Why not re-adopt that definition??

    And before you think I'm a militant Pluto-hater, I'm not. I really, truly don't care whether we call it a "planet" or not. But I *DO* think we need scientific consistency. You want to call Pluto a planet just because it's round? Well, then we need to add Ceres and various other objects out near Pluto, as well as the Earth's moon, and a bunch of moons of Jupiter et al.

    Why aren't the moons "planets" anyway? Seriously -- stop the knee-jerk reaction of "well, they're MOONS!" and seriously consider the question. They are round. They do ultimately orbit the Sun, even if they are also orbiting another body too. There's no really good reason to exclude them other than... well, another arbitrary definition. They aren't the most prominent body in their orbital region.

    So yeah, if we want to call all of these things [wikipedia.org] (except the Sun) a "planet," I'm perfectly fine with that. Or if you want to come up with some arbitrary definition that excludes satellites, I suppose I might be okay with that too. Or if you want to introduce a reasonable "clearing the neighborhood" metric [wikipedia.org], I'm okay with that too, because it does seem to be an important element of the dynamics of stellar systems regarding what ends up being a prominent object in a particular area around a star. And by any of those metrics, there's a big gap of several orders of magnitude between the eight major planets and the rest of the objects.

    This isn't any more arbitrary "non-scientific process of voting" criterion than looking at an arbitrary slice of the history of astronomy and endowing it with "authority" to determine what should be called a planet. Definitions can evolve -- and frequently do in science to deal with new data and ideas. As we look at exoplanets and other stellar systems, is "clearing the neighborhood" an important criterion? I think it might be -- given the unstable dynamics created when objects can't do that, which might influence possible chances for live development or sustainability, etc. But again, that's just an arbitrary definition -- like ALL of them are. But it would be based on a legitimate SCIENTIFIC concern.

    Lastly, I'll just note that a "mini-fridge" is still a refrigerator. We still call them "dwarf planets," because they're round. The new definition basically already implies that the word "planet" means a body that orbits the sun and is round due to gravitation. We just add "dwarf" when it doesn't satisfy an additional criterion. Everyone seems to be all bent out of shape because a "planet" was "demoted," but I really don't view it that way. All of this controversy could probably have been avoided if they just added "major planet" (or "uberplanet," which was a serious term proposed by one astronomer when the whole "clearing the neighborhood" concept was first proposed) for the eight, and then just left the rest as "planets." It seems this is all manufactured controversy because people don't like demoting something. In the age where everyone gets a trophy, you just can't have that sort of thing....

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  • (Score: 2) by theluggage on Saturday September 08 2018, @03:23PM

    by theluggage (1797) on Saturday September 08 2018, @03:23PM (#732221)

    This isn't any more arbitrary "non-scientific process of voting" criterion than looking at an arbitrary slice of the history of astronomy and endowing it with "authority" to determine what should be called a planet.

    It isn't any less arbitrary either. Even if the new definition wasn't an evil plot to demote Pluto - or prevent Eris becoming the tenth planet - it was, at best, an "appeal to tradition" to avoid the prospect of lots of new planets... and, yes, maybe the IAU could have avoided the issue by re-naming "planets" as "major planets" to make it clear that "dwarf planet" was a sub-category but... you know what? they didn't. They didn't need to re-define "planet" at all - its not like any categorisation that includes both Mercury and Jupiter is going to be scientifically useful, and in a few years we will have a shitload of data on weird and whacky exoplanets that will almost certainly need a future re-thinking of definitions. If the subject is "flamebait" then the IAU are the original trolls...

    Now, if there are any people out there seriously arguing that "Pluto is a planet, but Eris isn't" then by all means ridicule them (I don't think straw men exist in the Social Media age - you can always dig up someone with a convenient case of cognitive dissonance...)

  • (Score: 0) by Anonymous Coward on Saturday September 08 2018, @04:40PM

    by Anonymous Coward on Saturday September 08 2018, @04:40PM (#732248)

    there were precisely FIVE bodies that qualified: Mercury, Venus, Mars, Jupiter, and Saturn

    No, actually there were seven traditional planets. You’re forgetting the Sun and the Moon.