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Arthur T Knackerbracket has found the following story:
It turns out that Earth is not a planet. Asteroid 2016 H03, first spotted on April 27, 2016, by the Pan-STARRS 1 asteroid survey telescope on Haleakala, Hawaii, is a companion of Earth, too distant to be considered a true satellite.
"Since 2016 HO3 loops around our planet, but never ventures very far away as we both go around the sun, we refer to it as a quasi-satellite of Earth," said Paul Chodas, manager of NASA's Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California.
Asteroid 2016 H03 is proof that Earth has not cleared the neighborhood around its orbit. Therefore, under the definition of a planet vigorously defended by the IAU [International Astronomical Union] since the adoption of Resolution 5A on August 24, 2006, Earth is a 'dwarf planet' because it has not cleared its orbit, which is the only criteria of their definition that Pluto fails. (I think we'll eventually discover that very few of the 'planets' have cleared their orbits).
Most of us who were baffled by the IAUs declaration and outraged at the obvious discrimination of Pluto knew there was something wrong, even if we couldn't put our finger on it — we just 'knew' Pluto was a planet, right?
[...] Here's what all of us non-scientists intuitively understood all along: "A planet is defined as an astronomical body that "has not undergone nuclear fusion, and having sufficient self-gravitation to assume a spheroidal shape" — in other words, it's round and not on fire.
How could the distinguished scientists be so wrong?
-- submitted from IRC
(Score: 2) by Grishnakh on Tuesday April 04 2017, @01:46AM (12 children)
It's not irrelevant scientifically. Categorization is an important part of science; just ask any botanist or biologist whether they think it's "irrelevant" whether some species has one name versus another name, and which genus, family, etc. it's in. To them, it absolutely is.
Definitions change; that's what's happened here, and it's possible these definitions will change again as we learn more about other star systems. There's no such thing as devising a classification system that never changes in the face of new information.
(Score: 1) by khallow on Tuesday April 04 2017, @02:19AM (9 children)
It's not irrelevant scientifically. Categorization is an important part of science; just ask any botanist or biologist whether they think it's "irrelevant" whether some species has one name versus another name, and which genus, family, etc. it's in.
I quite disagree. Labels don't change the actual science. For example, the Aptostichus barackobamai [soylentnews.org] isn't going to behave differently, if it were the Aptostichus donaldtrumpus. Similarly, Saturn doesn't change whether or not there are a hundred planets or dwarf planets in our categorization system. What is different is that the current definition can't be extended to the rest of the galaxy while any definition based on roundness or mass is easy to extend.
(Score: 2) by Grishnakh on Tuesday April 04 2017, @02:45AM (8 children)
Terrible analogy. You focused on the species name (with a broken link, I'll add), not the genus name (aptostichus). If you changed the name to "homo barackobamai" (the same genus as humans), or worse, to "Apomastus barackobamai" (a different genus under the same family of spiders in Euctenizidae), it would cause a lot of confusion. The kingdom-phylum-class-order-family-genus-species classification system exists for a good reason in biology.
For now, the rest of the galaxy is basically irrelevant. We've detected over 1000 exoplanets now, but we still don't know much about them other than they're all pretty big (bigger than Earth) because that's all we can see from this distance. We can't even see if they're round; we can only assume they must be because our observations show that any mass that large achieves hydrostatic equilibrium, but we only know that from observing a small handful of samples in this one system. There's no way for us to see that in another star system without going there. We sure as hell aren't going to be able to see (any time soon) if those exoplanets have "cleared their orbits", since there's no way for us to resolve small asteroid-size objects from dozens of light-years away.
When we actually get data back from deep-space probes showing actual photos of some of these exoplanets and their systems, then we can talk about how good these definitions are. For now, they only really need to fit our own system, though they do seem to work OK for exoplanets too since they're all so big. We're probably not going to have to worry for a long time whether some exoplanet is a "exo-dwarf-planet" because we can't see anything that small.
(Score: 1) by khallow on Tuesday April 04 2017, @02:51AM (2 children)
If you changed the name to "homo barackobamai" (the same genus as humans), or worse, to "Apomastus barackobamai" (a different genus under the same family of spiders in Euctenizidae), it would cause a lot of confusion.
I didn't. Any labeling system which has the same hierarchical structure and category boundaries will have the same information content no matter what the labels are.
(Score: 2) by Grishnakh on Tuesday April 04 2017, @04:14AM (1 child)
Then your analogy makes zero sense. No one is proposing renaming "Pluto". They changed the classification. That's akin to changing the genus on that spider, not the species. The species name can be anything, it doesn't matter. That's why they got away with choosing such a crappy name for it. The genus (and family, order, etc.) names are very important, because they establish that species' relation to other species. This is just like how we call different bodies "planets", "comets", "asteroids", "stars", etc., to categorize them and distinguish them from one another.
(Score: 1) by khallow on Tuesday April 04 2017, @04:58AM
Then your analogy makes zero sense. No one is proposing renaming "Pluto". They changed the classification.
How so? The classification wasn't actually changed. Pluto is still Pluto no matter what it is named or how they choose to group it. And the groupings don't add anything scientifically - no matter what biologists say about planets. And this particular classification is already obsolete since it can't be applied outside of the Solar System (by definition), and even if one were to try for star systems where it would make sense to try, there is an artificial and onerous observation threshold that needs to be overcome merely to show any sort of clearing of the neighborhood. I think the informal classification "suspected planet" would become far more common than the designation "planet" for exoplanets, if this definition on hard to observe dynamics becomes official galaxy-wide. No one would care enough to actually make the classification work for most objects.
Then there's the implied meaning of "dwarf planet". There are certain adjectives that inherently mean that the object is not actually of the category of the bare noun, such as "fake diamonds" not actually being diamonds. But "dwarf" is not one of those words. If I were to say "dwarf mammoth" you wouldn't think that the object is not actually a mammoth. But "dwarf planets" are supposedly not actually "planets". This abuses the language.
(Score: 1) by khallow on Tuesday April 04 2017, @03:07AM (2 children)
We're probably not going to have to worry for a long time whether some exoplanet is a "exo-dwarf-planet" because we can't see anything that small.
It's already a problem because exo-dwarf-planets need not be small. If a several Jupiters mass exoplanet is hanging out in the L4/L5 points of a binary star system, it's not a planet by our definition (ignoring of course that the definition is specifically for the Solar System).
(Score: 2) by Grishnakh on Tuesday April 04 2017, @04:11AM (1 child)
Um, if I understand astrophysics right (and there's a good chance I'm mistaken), a body the mass of several Jupiters is more likely to be called a "brown dwarf star", not a planet.
(Score: 1) by khallow on Tuesday April 04 2017, @05:01AM
(Score: 2) by maxwell demon on Tuesday April 04 2017, @07:42AM (1 child)
But that's exactly what the IAU was doing. According to the rules of language, a dwarf planet should be a planet. According to the IAU rules, it isn't.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 3, Insightful) by AthanasiusKircher on Tuesday April 04 2017, @03:29PM
Well, I suppose that's the case, but only because the IAU doesn't append some sort of additional qualifier onto the major planets. But both planets and dwarf planets share two criteria, while (major) "planets" have a third. Implicitly, the two shared characteristics could easily be viewed as a more general interpretation of the word "planet," which is how I choose to view it from a linguistic sense.
It's kind of like comparing a mini-fridge to a refrigerator. If you just say the word "refrigerator" out of context, people will probably assume you mean a full-size home refrigerator (and not a mini-fridge or a walk-in restaurant fridge or whatever). We don't generally feel the need to preface "refrigerator" with qualifying terms like "full-size home refrigerator" or whatever in most contexts. And most normal people asked to define and give an example of the word "refrigerator" in English would probably think of the most common kind.
But there is ALSO a broader definition of refrigerator that has to do with shared characteristics, which would cover everything from mini-fridges to walk-in fridges. So, a mini-fridge can both be a "refrigerator" according to some shared criteria AND also not an exemplar of "refrigerator" as that term is generally pictured when referenced without qualification. If you want your audience to understand a term out of context, you'd likely say "mini-fridge" or "compact fridge" or whatever, because they don't satisfy the normal association of "refrigerator" out of context.
I know this may not be the way the IAU frames its rules exactly, but we could do the same analysis for any number of English terms. E.g., "house" vs. "dollhouse" or "doghouse" or whatever. There's some shared set of criteria that make all of them "houses" in some abstract sense, but without context nobody would think of a dollhouse or doghouse as included in the common definition of "house," and yet they still ARE "houses" (just for dolls or dogs). Without context, we assume "people house"; without context, the IAU assumes "planet" = "body that cleared its neighborhood."
That's how imprecise English normally works, with a lot of assumptions. But the IAU has to be give a more precise language definition for scientific terms... which basically doesn't seem to open the door for the free usage and connotations that happen with most English words in such circumstances. But I don't see any reason whatsoever that we shouldn't look at commonalities in definitions and conclude that a statement like "Pluto is still a planet, just a dwarf planet" is a valid utterance.
(Score: 2) by maxwell demon on Tuesday April 04 2017, @07:38AM
But they couöld instead have declared that there are two classes of planets, main planets and dwarf planets. Then Pluto would have been remained a planet, avoiding the confusing definition that something which is classified as "something planet" isn't classified as planet, and Mercury to Neptune would now be main planets. Main planets and dwarf planets would be subclasses of planets, as the names suggest, and you'd not only end up having the same distinction asnow, you'd even have a name for the class of objects that is the union of main planets and dwarf planets, namely planets.
The way they did it, we have now dwarf planets that are not planets, disregarding all rules of language, and we have no word for the class of objects that are either planets or dwarf planets.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by FatPhil on Tuesday April 04 2017, @12:02PM
And they'll tell you your nuts aren't nuts, your berries aren't berries, and that your fruit aren't fruit. Oh, and some of your flowers aren't flowers either. If any science had nomenclature by humpty dumpty, botany's it.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves