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posted by martyb on Monday April 03 2017, @06:54PM   Printer-friendly
from the we-need-cleanup-in-orbit-3 dept.

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


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  • (Score: 2) by AthanasiusKircher on Monday April 03 2017, @07:42PM (2 children)

    by AthanasiusKircher (5291) on Monday April 03 2017, @07:42PM (#488325) Journal

    Apparently the author doesn't know. As he himself says in TFA:

    I’m not qualified to define what ‘clearing the orbital neighborhood’ means, nor define the importance of the location of the barycenter of two bodies one orbiting the other. I only understand what most school children do, that a planet is round, and not on fire. I’ve attached an illustration.

    I really don't get why people are so upset about this. Even if the criteria are not precise (though this guy admits he doesn't know enough about "clearing orbit" criteria to have a clue whether they are precise or not). it seems excluding Pluto is about the only way to get to a reasonably consistent definition that doesn't balloon the "solar system" to a huge number of planets. Right now, there are something like a hundred potential dwarf planets [wikipedia.org] that could satisfy the definition of "round and not on fire," and the estimate is that there are probably 200 in the Kuiper belt, and a LOT more beyond.

    So what's his solution? He says his post is "satire" in the sense that he doesn't REALLY believe Earth is not a planet, but he doesn't propose an alternate definition that doesn't lead us to revise the definition of the "planets" in the Solar System every other week. If Pluto is so worthy of the designation, what about the other Kuiper belt objects? Or is he going to draw an arbitrary distance line from the sun? Or some other arbitrary distinction?

    Also, I can't even believe I'm still giving attention to this guy, but why does he care so much about 2016 HO3? Yes, it follows an interesting orbital trajectory with Earth, but there are a bunch of near earth asteroids [wikipedia.org] -- probably a few thousand bigger than 2016 HO3 -- why isn't he talking about them??

    Even one of the most prominent foes of the redefinition was instrumental in formulating the one of the metrics for orbital clearing [wikipedia.org] that shows a huge gap between the major planets and things like Pluto and Ceres. Instead of demoting Pluto though, his argument just wants to call the 8 major planets "überplanets," which is still creating an equivalent distinction, just prefixing a term on a different group. What difference does it make whether we have hundreds of "planets" and 8 "überplanets" vs. hundreds of "dwarf planets" and 8 "planets"? Given the much, much longer history of using the word "planet" alone for the major planets, it probably makes a little more sense to go with the "dwarf planet" idea... otherwise it's kind of like Starbucks calling a small drink a "tall."

    Lastly, is it even worth pointing out that Pluto is STILL a "planet" (a term that still basically follows his definition of "round and not on fire"), just a "dwarf" one?

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  • (Score: 0) by Anonymous Coward on Tuesday April 04 2017, @03:22AM (1 child)

    by Anonymous Coward on Tuesday April 04 2017, @03:22AM (#488514)

    So what's his solution? He says his post is "satire" in the sense that he doesn't REALLY believe Earth is not a planet, but he doesn't propose an alternate definition that doesn't lead us to revise the definition of the "planets" in the Solar System every other week.

    Um, yeah, he does. "Round and not on fire." As far as I can tell, you think he'll want it revised every week because you've assumed he wants to somehow exclude everything except the "Classic Nine", but he never says that.

    If Pluto is so worthy of the designation, what about the other Kuiper belt objects?

    Are they round and not on fire? Planets! (So not tiny irregular-shaped ones, nor any cold-fusioning ones that may exist.)

    Or is he going to draw an arbitrary distance line from the sun?

    Why? Surely things don't stop being rounded by their own gravity, or spontaneously combust, because of some arbitrary distance line?

    Or some other arbitrary distinction?

    Again, why? This guy gets enough things wrong*, there's no need to criticize him for wanting arbitrary distinctions when you're the only one proposing them.

    (IMO, the fact that many satellites become planets under such a definition is far more likely to bother people and result in arbitrary distinctions than "b-b-but... hundreds of planets!". Personally, I don't mind that either -- I'm quite capable of handling the idea that something can be a planet and a moon at the same time.)

    Even one of the most prominent foes of the redefinition was instrumental in formulating the one of the metrics for orbital clearing that shows a huge gap between the major planets and things like Pluto and Ceres. Instead of demoting Pluto though, his argument just wants to call the 8 major planets "überplanets," which is still creating an equivalent distinction, just prefixing a term on a different group. What difference does it make whether we have hundreds of "planets" and 8 "überplanets" vs. hundreds of "dwarf planets" and 8 "planets"?

    Well, the difference is that Stern's scheme has 3 labels; both "überplanets" and "unterplanets" are subsets of "planets". These labels make grammatical sense.

    Lastly, is it even worth pointing out that Pluto is STILL a "planet" (a term that still basically follows his definition of "round and not on fire"), just a "dwarf" one?

    Well, that's exactly the problem; under the IAU's definitions, a dwarf planet is not a planet at all. In an attempt to split the middle, they picked the worst nomenclature possible.

    You can either have the set "planet" with two subsets "dwarf planet" and "??? planet" (where ??? can be any adjective, such as "classical" or "über-"), or you can have two sets "planet" and "???" (where ??? is anything not of the form "$ADJECTIVE planet"; "planetoid was suggested (but has unfortunate history as a synonym for "asteroid"), and I think "planetino" was tossed around?); I don't have strong feelings either way. But having mutually-exclusive sets labeled "planet" and "dwarf planet" is just a horrible thing to do.

    *My favorite was "since a planet is a planet regardless of what system it’s in (unless the IAU would like to vote against that?)"; of course the very IAU resolution that demoted Pluto specifically defined a planet to be "in orbit around the Sun". Or right in TFS, we have "(I think we'll eventually discover that very few of the 'planets' have cleared their orbits)"; as you say, the numerous Earth-crossing asteroids, but also the trojans and plutinos, have already proved that few if any planets have "cleared their orbits" -- for a sufficiently ridiculous definition of that phrase. It's a pretty valid criticism of the IAU definition that it doesn't specify a definition for "cleared the neighborhood around its orbit", but substituting ridiculous definitions and saying "See, it makes no sense!" is silly, and imagining that 2016 HO3 is somehow the first body you can combine with your ridiculous definition to "discredit" the IAU is both silly and astronomically illiterate. Frankly, I'm not too happy to be defending this clown...

    • (Score: 2) by maxwell demon on Tuesday April 04 2017, @07:21AM

      by maxwell demon (1608) on Tuesday April 04 2017, @07:21AM (#488568) Journal

      Um, yeah, he does. "Round and not on fire."

      He might still want to add something else. Or he'll have to label a soccer ball a planet because it is round and not on fire (of course as soon as someone sets it on fire, the soccer ball loses its planetary status. I'm not sure whether it then is a sta, though ;-))

      --
      The Tao of math: The numbers you can count are not the real numbers.