NASA Scientists Propose New Definition of Planets, and Pluto Could Soon Be Back (sciencealert.com) 213
Rei writes: After several years of publicly complaining about the "bullshit" decision at the IAU redefining what comprises a planet, New Horizons program head Alan Stern and fellow planetary geologists have put forth a new definition which they seek to make official, basing planethood on hydrostatic equilibrium. Under this definition, in addition to Ceres, Pluto and other Kuiper Belt objects, large moons like Titan and Europa, as well as our own moon, would also become planets; "planet" would be a physical term, while "moon" would be an orbital term, and hence one can have a planetary moon, as well as planets that orbit other stars or no star at all (both prohibited under the current definition). The paper points out that planetary geologists already refer to such bodies as planets, citing examples such as a paper about Titan: "A planet-wide detached haze layer occurs between 300-350 km above the surface; the visible limb of the planet, where the vertical haze optical depth is 0.1, is about 220 km above the surface."
That's no moon (Score:3, Funny)
oh wait, it is just a moon.
Re:That's no moon (Score:4, Interesting)
Moons are next on the hit list.
At last count Jupiter has 67 so-called moons: The four Galilean moons, plus 63 rocks.
We really need to clamp down on what counts as a moon, or every bit of space-trash will demand to be listed.
Re:That's no moon (Score:5, Interesting)
Any "space-trash" that demands to be listed as something else needs to be immediately identified as a "sentient being", and on behalf of all of us Earthlings the UN needs to publicly apologize to him/her/it. That is simple playground rules: you don't want to insult anybody that much bigger than you are.
As to everything else, I think the planetary geologists have it right. If it is big enough to be rounded of its own volition, it is a planet. And planets that go around another planet more quickly than they go around their star are also moons.
Corollary: that makes Earth the larger part of a binary planetary system. Which puts proper emphasis on the way the Moon creates tides that keeps the hydrosphere stirred up, which has had a major impact on how life has evolved here. Exoplanetary explorers should look for other binary planets in the Goldilocks zone as these are much more likely to have life that is similar to Earth life.
(Is a "bazinga!" called for here? Was this just another Sheldon impersonation, or did I accidentally say something insightful?)
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that makes Earth the larger part of a binary planetary system.
There is a rule to avoid that. If the common centre of mass is inside one body, Earth in this case, it is considered a planet & moon, not a binary.
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That's one of those foolish rules put forth by the idiocy contingent of the IAU.
The barycenter of the Earth - Moon binary is outside of the Earth's hard inner core, in the region of the liquid outer core. This is the center or neutral point of the tidal forces acting on the Earth. No one has yet looked at the effects of these tides on the outer core's liquidity, or its electromagnetic properties, mostly because astronomers look upward and geologists look downward and there is a very serious failure for eit
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Very insightful stuff. Out curiosity, what are your thoughts on formally recognizing the Sol/Jupiter binary system -- it's barycenter being outside of the Sun entirely? All of this terminology just goes so many levels deep...fun stuff haha.
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My thinking has been too Earth-bound to consider the Sol - Jupiter relationship. But I see others are thinking about it; there are several lay articles and apparently some more serious articles on the web. But I haven't done any critical reading on the subject.
There does seem to be a correlation between Jupiter's orbital period and the sunspot cycle as both are roughly 11 years. But if there is an underlying mechanism (not conveniently dismissible as "coincidence"), it seems more likely that the mechanisms
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I'd advise you to do your critical reading. Look at the numbers and you'll find that the range of solar sunspot cycles is from 8.8 years to 14 years ; the corresponding orbital period for Jupiter is 11.875 years - 4331 days - with a variation of a lot less than a day. Remember that Ole Roemer was
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As I know I mentioned before, I doubt that there is a gravitationally mediated interaction between Jupiter and the solar cycle, and if there is a electromagnetic interaction, then that would involve Saturn as well as Jupiter, and probably Earth. Both Saturn and Jupiter have a strong impact on the solar wind. During the years when they are in close heliocentric conjunction, Jupiter's magnetotail and the bow wave of Saturn's magnetosphere are trying to occupy the same space. There has got to be some interesti
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Without getting into essential complexities (e.g., the orbits are not circular, but elliptical), there's one very simple check that you don't seem to have considered. The 1.3 difference in orbital inclination between Earth and Jupiter means that the projection of the Earth's magnetotail out to Jupiter's orbit will be up to 23 million km (nearly 1/4 AU) above or below the line of
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You don't bother to look up anything you've never been taught, I guess.
The magnetospheres of the planets that have them are several times the radius of the physical planet. But even greater than that, the field effects of standing waves and turbulence in the solar wind extend well beyond the magnetospheres that shape them. Remember (or look it up since it seems like you've never been taught about it) that the solar wind is composed of mono-atomic ions and free electrons moving at very high speeds. What lie
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Anyway, for the silent audience, I did a couple of other calculations last night. (Something you seem remarkably resistant too. Whether that's the "mystic" part of your chosen persona, or the "goat", I neither know nor care.) Given the respective diameters of the Sun and the Earth, and their spacing, it is a simple matter to calculate that the optical tail, the umbral shadow, of the Earth is around a million km long. How lon
Re:Mike Brown was the Clown Responsible (Score:5, Informative)
I find that title hilarious.
Pluto's back? (Score:1)
As far a I am concerned, it never went away.
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Take it up with NASA and get a medal. Of course, they might tell you that you don't know what you're on about, but then you might just accept that as evidence of just how right you are.
Maybe (Score:5, Funny)
Maybe stop changing arbitrary definitions. Pluto was always a planet. Fuck you, NASA and shitty celebrity "scientists" like Neil Tyson.
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Maybe stop changing arbitrary definitions.
Definitions like this will be arbitrary, and it just comes down to what makes it easier to write journal articles (where IAU has any authority). If Pluto was included in planets, there are quite a few orbital dynamics and evolution papers that would need to use the phrase, "The planets excluding Pluto....". There are plenty of papers on geology and atmospheric dynamics that wouldn't care about the orbit and would benefit from a definition like proposed here. There are others that would need to take a def
Re:Maybe (Score:5, Interesting)
Clearly given that people like Stern have regularly given interviews decrying the decision, and going so far as to call it "bullshit" (can you say that at NASA?), it's clearly not the storm in a teacup that you want to present it as.
What the proponents did was take a term widely used by planetary geologists and have it mean something completely different - akin to dentists suddenly declaring to doctors that the heart is no longer an organ and to stop referring to it as one. And contrary to your presentation of why they did it ("to make it easier to write journal articles") without fail every last supporter I've seen interviewed about their vote has given some variant of the following reason for why they voted the way they did: "I don't want my daughter having to memorize the names of hundreds of planets." Which is so blatantly unscientific it's embarrassing that such a thing would influence their decision at all on a scientific matter.
The IAU vote was narrow, at a conference only attended at all by a fraction of its membership, on the last day when a lot of the people opposed to the definition they passed had already left because it had looked up to that point like there was either not going to be a vote at all , or one on a hydrostatic equilibrium definition - all options that they were fine with. Only 10% of the people who attended were still around.
I have a lot of issues with the last vote, and that's just the start. Here's my full list:
1. Nomenclature: An "adjective-noun" should always be a subset of "noun". A "dwarf planet" should be no less seen as a type of planet than a "dwarf star" is seen as a type of star by the IAU.
2. Erroneous foundation: Current research agrees that most planets did not clear their own neighborhoods, and even that their neighborhoods may not always have been where they are. Jupiter, and Saturn to a lesser extent, have cleared most neighborhoods. Mars has 1/300th the Stern-Levison parameter as Neptune, and Neptune has multiple bodies a couple percent of Mars's mass (possibly even larger, we've only detected an estimated 1% of large KBOs) in its "neighborhood". Mars's neighborhood would in no way would be clear if Jupiter did not exist - even Earth's might not be. Should we demote the terrestrial planets as well?
Note that the Stern-Levison parameter does not go against this, as it's built around the ability of a planet to scatter a mass distribution similar to our current asteroid belt, not large protoplanets.
3. Comparative inconsistency: Earth is far more like Ceres and Pluto than it is like Jupiter, yet these very dissimilar groups - gas giants and terrestrial planets - are lumped together as "planets" while dwarfs are excluded.
4. Poor choice of dividing line: While defining objects inherently requires drawing lines between groups, the chosen line has been poorly selected. Achieving a rough hydrostatic equilibrium is a very meaningful dividing line - it means differentiation, mineralization processes, alteration of primordial materials, and so forth. It's also often associated with internal heat and, increasingly as we're realizing, a common association with subsurface fluids. In short, a body in a category of "not having achieved hydrostatic equilibrium" describes a body which one would study to learn about the origins of our solar system, while a body in a category of "having achieved hydrostatic equilibrium" describes a body one would study, for example, to learn more about tectonics, geochemistry, (potentially) biology, etc. By contrast, a dividing line of "clearing its neighborhood" - which doesn't even meet standard #2 - says little about the body itself.
5. Mutability: Under the IA definition, what an object is declared as can be altered without any of the properties of the object changing simply by its "neighborhood" changing in any of countless ways.
6. Situational inconsistency: (Related) An exact copy of Earth (what the vast majority of people would consider the prototype for what a planet s
Re:Maybe (Score:5, Interesting)
Wow.
TL;DR but I got through enough of it to realize that most, and maybe all, the points are cogent. Above post should be stuffed down the throats of every IAU member who voted for their absurd definition of planet until they can regurgitate those points, with meaning.
Some astronomers are stupid. The phrase "educated beyond the level of their intelligence" comes to mind. This idiots should have been taught somewhere along the way that their expertise in one narrow field does not endow them with the authority to mess about in other disciplines like linguistics.
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There's a lot of words but most of the points don't seem to make a lot of sense.
1. "Adjective nouns" need to have similarity to "noun" but aren't necessarily a subset. Gummy bears aren't a subset of bears either.
2. I'd like to see a citation on this. I highly doubt that you can simulate the formation of a solar system where multiple Mars analogues can coexist in the same orbit over billions of years without an accident happening to one of them.
Alone the fact that neither of the terrestrial planets have an o
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Gummy bears are not a scientific term. Besides, the IAU itself already uses the word dwarf in this manner. Dwarf stars, dwarf galaxies... but carved out an inexplicable exception for dwarf planets.
False equivalenc
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And more to the point, the biggest problem with the concept of Mars clearing its orbit is that its orbit was already largely cleared [nature.com] when it formed. According to our best models, Jupiter reached all the way in to around where Mars' orbit is today, and had cleared almost everything to around 1 AU.
How did the asteroid belt get there, then? That's a question, not a polemic.
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The short of it, Jupiter moves things around; it's very good at scattering other bodies, even large ones. First it dragged outer populations into the inner solar system, then scattered inner solar system material out, and then on its retreat pulled outer solar system material back in. It's actually a very big deal that it did that, as it brought ice into the inner solar system.
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Indeed, on both counts. And in particular I like the word "rogue planet". Again you have an adjective imparting additional information about another object ("Rogue X"), "rogue" can be readily quantified ("Not in a stable orbit around any particular star or cluster of stars"), and it's a very evocative term. And rogue planets are absolutely expected according to our current models. They'll be incredibly difficult to find, but they're out there.
We're also coming to the realization that there's a lot of ob
Re:TL;DR something you claim is cogent...? (Score:5, Informative)
That's just the issue: that's not what happened. The IAU discussion was a disaster. Here's the timeline:
2005: The IAU appoints a committee to investigate the issue and generate a proposal. The committee investigated the issue for a year.
The IAU meeting is scheduled from 14-25 August 2006.
16 August: The committee recommends a definition based on hydrostatic equilibrium. No "cleared the neighborhood" nonsense. They publish their draft proposal.
18 August: The IAU division of planetary sciences (aka, the people who actually deal with planets) endorses the proposal.
Also 18 August: A subgroup of the IAU formed which opposed the proposal. An astronomer in the group (aka, someone who studies stars, not planets) - Julio Ángel Fernández - made up his own "cleared the neighborhood" definition. While most of the membership starts to trickle away over the next week, they remain determined to change the definition.
22 August: The original, hydrostatic equilibrium draft continued to be the basis for discussion. There were some tweaks made (some name changes and adjusting the double-planet definition), but it remained largely the same.
Late on 22 August: Fernández's group manages to get to just over half of the attendance at the (open) drafting meeting, leading to a very "heated" debate between the two sides.
22 to 24 August: The drafting group begins to meet and negotiate in secret. The last that the general attendance of the conference knew, they'll either end up with a vote on a purely hydrostatic definition, or (more likely) no vote at all due to the chaos. Attendence continues to dwindle, particularly among those who are okay with either a hydrostatic definition or none at all.
24 August: The current "cleared the neighborhood" definition is suddenly proposed and voted on on the same day. Only 10% of the conference attendance (4-5% of the IAU membership) is still present, mainly those who had been hanging on trying to get their definition through. They pass the new definition.
It's not generally laypeople who are upset about how it went down, it's IAU members. Many have complained bitterly about it to the press. The IAU's own committee of experts was ignored, in favour of a definition written in secret meetings and voted on by a small, very much nonrandom fraction of people, the vast majority of whom do not study planets.
If there's one thing I hate, it's people who pretend that anyone who opposes the IAU definition does so because they're ignorant morons overcome by some emotional attachment to Pluto, when in reality it's been planetary scientists themselves who have been the definition's harshest critics, because it's an internally self-inconsistent, linguistically flawed, false-premise-based definition that leads to all sorts of absurd results and contradicts terminology that was already in widespread use in the scientific literature.
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Also 18 August: A subgroup of the IAU formed which opposed the proposal. An astronomer in the group (aka, someone who studies stars, not planets) - Julio Ãngel FernÃndez - made up his own "cleared the neighborhood" definition.
While we're taking role titles literally, don't forget that as an astronomer, Sr Fernandez is only responsible for naming stars, not actually studying them.
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But... but he did it first!
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The IAU vote was narrow,
Really? Their notes from conference indicate that the resolution "was passed with a great majority.": https://www.iau.org/news/pressreleases/detail/iau0603/ [iau.org]
1. Nomenclature: An "adjective-noun" should always be a subset of "noun". A "dwarf planet" should be no less seen as a type of planet than a "dwarf star" is seen as a type of star by the IAU.
No. A dry lake is not a type of lake, for example. "adjective-noun" can mean "something in the category described by adjective but resembling the nouns". You can't make Pluto a planet by playing a cheap word game.
2. Erroneous foundation: Current research agrees that most planets did not clear their own neighborhoods
Nothing from the IAU's resolution indicates a purpose to consider the historical conditions.
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Good points. But they are basically off topic.
It doesn't matter one whit what terms scientists use in their cloistered jargons. That's why they have jargons.
It does matter when a body of scientists attempts to mold the common tongue to their narrow purposes. Which is what happened with the IAU: they overstepped their area of authority, which is astronomy, to dabble in an area where none of them have any training or standing, which is the study of natural languages, or linguistics. It makes them look like
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The problem, as I see it, is that journalists have stopped translating, and echo the jargon even when it doesn't translate well.
Even worse than the astronomical definition for planet being out of touch with the rest of the world is the astronomical definitions of gas (only hydrogen and helium), metal (all other elements), and ice (any molecules comprising both "gas" and "metal" atoms). To an astronomer, nitrogen is a metal, and methane gas is an ice.
Re: Maybe (Score:2, Funny)
Yeah, never understood why this Tyson guy gets so much attention. What did he ever do, except beat up some people in a ring and biting off someone's ear, and beating his wife and stuff?
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Yeah, never understood why this Tyson guy gets so much attention. What did he ever do, except beat up some people in a ring and biting off someone's ear, and beating his wife and stuff?
Picturing Neil deGrasse Tyson with a face tattoo just made my day. I imagine it would either be something like a comet under his eye instead of a tear drop, or maybe something just totally out there and not even physics/space related.
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Maybe stop changing arbitrary definitions. Pluto was always a planet. Fuck you, NASA and shitty celebrity "scientists" like Neil Tyson.
Wow, who actually gives a shit, really? What difference does it make if Pluto is defined as a planet, a dwarf planet, an ice cube or numero uno place in the galaxy? How does that effect anyone enough to get uppity about it? Move on with your life.
Taxonomy is always arbitrary (Score:2)
Maybe stop changing arbitrary definitions.
Why? If the definitions already were arbitrary then what's wrong with changing them to a different variety of arbitrary? Especially if the new definition makes more sense. We're talking about taxonomy [wikipedia.org] here, not some law of physics.
Frankly the term planet is probably too broad to be super useful by itself. It's kind of like a genus [wikipedia.org] for space objects and we need to define the species. Jupiter and Earth are both considered planets but they aren't even remotely similar to each other aside from being big an
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Who said anything about dogma, you ass clown? Words have definitions and wantonly changing them means every written use of the word now needs to be dtae checked to determine which version of the definition was intended. It's the same with the "kibibyte" horseshit. STOP CHANGING THINGS FOR NO REASON.
The definition of "planet" was, is, and always will be arbitrary. They've been obsessed with "correcting" an arbitrary definition for about a decade now, and they show no fucking signs of stopping. Have we h
And what are the other terms? (Score:3)
OK, but do you call something that orbits a star (like a, er, planet).
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OK, but do you call something that orbits a star (like a, er, planet).
A space station? On the account that it's no moon...
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And what do you call things that orbit barycenters, like all things do?
This is what happens when eggheads aren't put to task building weapons for war and aren't bullied enough - they lose all discipline and just faff about willy-nilly.
As an egghead myself, FUCK YOU OTHER GUYS! Stop senselessly changing existing definitions and creating MORE ambiguity! You're ignoring basic principles of your field!
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That's no egg... it's a testicle !
You're not an egghead, you're a testicle head. And frankly for somebody who seems to think the primary purpose of science is building instruments of death (as opposed to the reality where that is a major perversion of science) - that's the kindest and most euphemistically polite term I can think of.
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Pluto would be a Planet orbiting Sol. The Moon would be a Planet and moon of Earth. So you have Astroids, Planets, and Comets (Comets being Asteroids that have tails). Earth has one planet orbiting it, Luna or the Moon, It has many Astroids orbiting it. This system works no matter what star system you are dealing with.
Re:And what are the other terms? (Score:5, Interesting)
Indeed, he is flagrantly biassed. He was the head of the New Horizon's project - which just sent us a huge amount of data to study on Pluto. Studies which cost money, and having Pluto not deemed a planet anymore has, he says, made it harder to drum up funding for that research.
The answer of course is: because everything in our solar system should be studied - not just planets. One of the greatest achievements in recent astronomy has been landing a probe on a comet, because it taught us a great deal about comets (things we couldn't learn from the remnants that sometimes fall on earth). Studying mars is cool - but we SHOULD be putting probes on Eris as well.
Good probes to Titan, Europa and Ganymede are important studies to undertake in the near future - they are among the highest likelihood cases for life elsewhere in the solar system. Europan bacteria would be a fantastic discovery - Europan 'fish' an unlikely but amazing bonus - but we will never know if we don't go look.
If anything looking at planets is near the bottom of the priority list. Most of the planets are gas giants - there's only so much you can learn from something you can't land on.
The definition is fine (Score:3, Insightful)
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to over a 100 objects seems a bit silly
Why? Why not further classification to rocky planets and gas giant planet also? Note I come from a geophysical background.
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Exactly. I think Stern's always been on the right side of this. The original paper that the Stern-Levison parameter comes from has a great system laid out, where you have a bunch of adjectives that you can apply to different bodies based on their varying physical (composition, size) and orbital parameters, and you can use any combination of them as needed. Which seems to me to be so obviously the right solution.
Re:The definition is fine (Score:5, Insightful)
If they had simply stopped there, that wouldn't have been a problem. The problem is that they didn't. They declared that dwarf planets aren't planets at all - which is nonsense. Mars has far more in common with Pluto than, say, Jupiter. If anything should have been separated out, it's the gas and ice giants from the rocky/icy planets.
Hydrostatic equilibrium is a very meaningful dividing line to split groupings on. If a body is in hydrostatic equilibrium, it's experienced dramatic geologic change in its history - differentiation, tectonics, internal heating, generally fluids (particularly liquid water), and on and on. It's the sort of place you go if you want to learn about planetary evolution or search for life. If a body is not in hydrostatic equilibrium, it's made of primordial materials, preserved largely intact. It's the sort of place you go to learn about the formation of our solar system and its building blocks.
It's rare that nature gives you such clear dividing lines, but when it comes to planets, it has. It's not perfect - you can (and do) have bodies that straddle the border and are only partially or slightly differentiated. But in general, nature has drawn an obvious line in the sand, and we should respect that.
Is Earth's orbit clear? No, we have a huge massive object co-orbiting with us. Is Neptune's orbit clear? No, it has Pluto in it. They try their hardest to pretend that the IAU actually chose a "gravitationally dominant" standard, but that's not what they actually put in the definition. The standard in the definition is "cleared the neighborhood".
And it's based on a false premise - that each planet cleared its own neighborhood. Which is just pseudoscience. All of our models show that Jupiter, and to a lesser extent Saturn, cleared most of the solar system, including the vast majority of the clearing around Mars, and a good fraction around Earth (lesser around Venus). Mars did not clear its own neighborhood. Nor is it gravitationally dominant in its neighborhood; the vast majority of asteroids are in orbital resonance with Jupiter and not Mars.
And I've heard some people try to sneak around this by saying "Okay, maybe it isn't gravitationally dominant / cleared its neighbood now, but it has enough of a Stern-Levison parameter that it would have been had Jupiter not existed". First off, that's changing the definition yet again (to "would have cleared its neighborhood if no other planets were there"). But beyond that, it's abuse of the Stern-Levison parameter. The Stern-Levison parameter is built around a body's ability to clear asteroids - bodies with the current size and orbital distribution of our asteroid belt. Not protoplanets. In the early solar system it was the ability to clear protoplanets that caused neighborhoods to be cleared. Jupiter got rid of some really massive things that were forming in and near the inner solar system. There's a reason why our planetary system has such an unusual size distribution: the inner planets start getting bigger, the stop getting bigger, then get small, then debris, then something huge. That "something huge" stripped the building blocks out of the inner solar system, preventing it from becoming dominated by super-Earths. Saturn appears to have been our savior - its (delayed) formation appears to have stopped Jupiter's inward migration.
And even just going with the Stern-Levison parameter - Neptune has a Pluto-sized body in its "neighborhood". Now, Pluto may be small compared to Neptune, but compared to Mars it wouldn't be - yet Mars has a much lower Stern-Levison parameter than Neptune. Again: the only reason Mars doesn't experience stuff like this is because Jupiter cleared its neighborhood for it.
Back? It never left. (Score:2)
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Astronomers apparently decided they wanted a little more precision in their terms when talking to other astronomers. The rest of us appear to just be getting angry when overhearing a conversation not intended for us and I don't think it really matters to us whether astronomers define Pluto as a planet or a different technical term.
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Who are you and I to correct astronomers? After all those office workers who call the beige box a "hard drive" think we are getting it wrong when we try to correct them, have you considered that this may be a similar situation?
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not doing so makes you look ignorant, especially when your kids come up to you and tell you you're wrong because a textbook only has 8 planets listed.
It's a good chance for a teaching moment for your kids: that the establishment, and especially textbooks, can be wrong.
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that the establishment, and especially textbooks, can be wrong
And what are you teaching them? To distrust current scientific consensus in favour of a feeling? Leave that to the sunday school, they do enough to fuck up kids minds as it is.
The textbooks aren't wrong. In fact they are correct at the time they were written. A better thing to teach kids is that scientific understanding and definitions get refined as time goes on. Then maybe we can finally have a generation of kids who are able to trust in scientific method and finally piss off homeopathy and all those othe
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And what are you teaching them? To distrust current scientific consensus in favour of a feeling?
Hopefully not. Hopefully you'll teach them how to think for themselves. To look at the evidence, and not blindly follow. That way leads to insanity.
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Hopefully you'll teach them how to think for themselves.
That's a natural part of it, but we don't have the ability to test every scientific fact that is published. So when all the textbooks, wikipedia, the majority of astronomers and the actual association responsible deciding what to call something decide Pluto is not called a planet, the options are to go with it or disprove it manually. I certainly will not be teaching someone to just say "what do these experts know anyway, this one person thinks differently, by the way pass the kale, David Wolfe says it cure
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and it doesn't fucking matter
Good thanks for clarifying your original position on the matter. So then you're actually okay with your kids learning correct definitions. Nice to know
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What's the point (Score:2)
What's the point of these taxonomical exercises? Like, who gives a fuck?
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What's the point of these taxonomical exercises? Like, who gives a fuck?
Those that do, and those that don't?
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If you were to categorize planets by race, what race would Pluto be? In my opinion Pluto would be a Negro.
That's offensive, AC.
Pluto is clearly a non-first-born asian. Small, cold, and distant.
how about the obvious definitions? (Score:3)
A planet is any body in hydrostatic equilibrium (nearly spherical) orbiting a star.
A moon is any solid body orbiting a planet.
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Also, if that definition gets chosen you can look forward to decades of drama after every new TNO discovery about whether that object is in hydro-static equilibrium or not. Can you imagi
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So? That's bad how?
For almost all bodies, this is pretty obvious. For objects directly on the border, you can call them "borderline" or "indeterminate". It
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http://vignette3.wikia.nocooki... [nocookie.net]
to this
https://i.redd.it/q6kn9ox71tmx... [i.redd.it]
Is it obvious? (Score:2)
Is the moon orbiting the earth? Or are the two orbiting each other as they orbit the sun?
In the case of the earth, the barycenter is within the earth. But the barycenter for Pluto and Charon is outside of Pluto...
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You just answered your own question.
Pluto could soon be back (Score:2)
That's a relief, Mickey's been searching for him for ages.
Makes Sense (Score:2)
Imagine a planet orbiting a star, that due to gravitational influence of other planets (or another passing star) was kicked out of the system. Under the current definition, it's suddenly no longer a planet. Likewise, if tw
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> many moons would become planets
They could be satellite planets. Just as we now have dwarf planets, rogue planets, terrestrial planets, and gas giant planets.
For objects like Pluto vs. those like Earth, we could use a terms like 'major' and 'minor' (eliminating the term 'dwarf') to denote those bodies that 'dominate their orbit' or whatever measure the current definition of planet uses. Yes, this would involve also messing with the current definition of 'minor planet'.
I really do like the idea of a mo
Question... (Score:5, Interesting)
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Personally I think the whole Pluto being a planet vs it being a dwarf planet makes about as much sense as arguing about whether American football deserves being called a football because players spend most of their time holding the ball and running around with it.
Off topic, but it's because the game evolved from a game where the primary mode of advancing the ball was either kicking it or batting it with your arms or hands.
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Pluto: Kick me all you want, but ... I'll be back. (Score:2)
Oh, you actually want a real rule? Then how about any large body that directly orbits a sun? Now, define large: diameter, atmospheric pressure (Do we call it a planet if it doesn't have an atmosphere?) "weight", mass, temperature, internal composition, a definab
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Oh, you actually want a real rule? Then how about any large body that directly orbits a sun? Now, define large: diameter, atmospheric pressure (Do we call it a planet if it doesn't have an atmosphere?) "weight", mass, temperature, internal composition, a definable surface or what-not AND remember to define exactly what a sun is and we're done.
All (non-accelerating) reference frames are equally valid. The sun orbits Earth just as much as Earth orbits the sun. Barycenters and whatnot.
Science cannot control language (Score:2)
The ultimate stupidity of all of this is the misguided notion that language is simply rational, and that it can be defined beforehand in its rational character by a committee decision. The fact of the matter is that language is developed by use. It's stupid that we are told "a spider is not a bug because a bug is an insect and an insect has six legs." Who ever decided that a bug meant a thing with six legs? Certainly "insect" does, but "bug" has always in actual use meant just about anything small. We somet
The problem with this new definition... (Score:2)
That there's something sure big enough, and sure round enough, so your momma would have to be a planet too.
Everything round is a "planet" now. (Score:2)
"A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters."
If that's a little too jargony for you, their 'layman's version' is simply: "Round objects in space that are smaller than stars."
I don't know about this. By this really simplistic definition, not only are most moons now "planets", but so are a lot of asteroids and comets (of all sizes). Untold thousands of objects in our solar system will now become "planets". There's also no real clear dividing line on shape. What's the objective definition of "a spheroidal shape"? Even the Earth is far from perfectly round, so where's the line on jagged asterorids?
Under this definition, if I throw a marble out of the ISS, i
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OK, but what does "sufficient self-gravitation" mean? There's clearly no actual number objective number there, because if there were it should be calculable and put right in the proposal. They are hand-waving based on the empherical evidence that the body in question is roughly round.
So what they are saying is that a particular largish body that happens to be round may have originally had some outside help, but *currently* has sufficient gravitation to KEEP itself round (barring some collision with a larg
What BS (Score:2)
"To wit: a common question we receive is, “Why did you send New Horizons to Pluto if it’s not a planet anymore?"
I call BS on this.
So there's all these people out there who are aware that Pluto exists, and that it was demoted to non-planet, and that we're sending a probe there, yet these same people cannot figure out why we would send a probe there? And these same people are also *unaware* that we send probes to things like the Moon and various asteroids, let alone deep space?
Suuuuuuureee.
Pluto lobbyists at work (Score:2)
This is a prime example of how money corrupts science. The scientist in question needs grant money, and he can't get it if Pluto isn't a planet.
Likewise, the citizens of Pluto now can't exercise their planetary rights because Pluto isn't a planet anymore. As a non-planet they aren't eligible for grant money designated for planetary authorities; they now have to get their monies from the less-funded "heavenly bodies" fund, which already has a waiting list.
The demotion has also caused issues with the accredit
Doesn't seem that hard (Score:2)
To properly define what a planet is, I think you need to first define what a moon is.
Moon: a body that orbits another non-stellar body where the center of mass is within the larger body's radius.
Planet: a spherical body that is not a moon or star. Sub-groups include gas giants, terrestrials, minor planets, double planets, etc.
I'm probably missing some nuance or details but you get the picture.
Beating a dead horse (Score:2)
During the IAU meeting which categorized Pluto as a dwarf planet (or plutoid), there were two competing definitions. One of them was functionally identical to this definition. It was struck down.
Calling the moon a planet (Score:2)
That's from the same guys who call oxygen a metal I suppose
Finally (Score:2)
"Pluto is a planet! Equal rights for Pluto!" - alien from Pluto, award winner in the young fan division in the Masquerade at Worldcon 2008.
Re:Wow (Score:5, Interesting)
Things are finally going back to normal.
Nope. I am fine with Pluto going back to being a planet, but MOONS ARE NOT PLANETS. The concept of a "planet" has been around for millennia, and the moon (and later Jupiter's Galilean moons) have never been considered planets. We need to stop with the arbitrary redefinition of common words. If astronomers want a term to refer to hydrostatically stable bodies, they should make up a new word rather than trying to steal one that is already in use.
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I sympathize with the sentiment, but first, words change. Even technical terms. Second, fixing scientific classification terms based on levels of knowledge far, far out of date is not practical. I mean, planet comes from Greek - and they quite literally had no idea what they were.
Re: (Score:2, Offtopic)
The concept of a "planet" has been around for millennia, and the moon (and later Jupiter's Galilean moons) have never been considered planets.
Right, and if there's one thing I know, it's that the things that people thought millennia ago should never ever be challenged, ever. Tradition is sacrosanct and if they thought it was true 2,000 years ago, then damnit it's still true today. This is why everyone still prays to Zeus up there on Mt. Olympus, and why we always will. It's also why I know that the heliocentric model is bullshit, because for millennia we knew that the sun goes around the Earth. It's just common sense.
I also know that the so-c
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Do we have to go from nothing is a planet except 8, to everything is a planet if it's round?
We could rename the first category to "plan8".
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Actually New Horizons was mostly funded by Clinton, since it was launched in 1997 and all...
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New Horizons is also the name of the satellite that sent those pretty pix of Pluto last year.
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2+2 is equal to 5 for arbitrarily large values of 2.
I'll make you a deal, you get your god to stop being such a petulant ass and I'll give him the respect he deserves.
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Thankfully, God has made a way of escape through Jesus Christ, His Son (John 3:16). The choice is yours alone to make. Do you really believe that the Creator is âoeThe God who wasn't thereâ as atheists allege. Every watch has a maker, and I assure you that the universe has a Maker as well. It is not only improbable; but impossible that this universe just happened, let alone that it evolved from some chaotic explosion... A BIG BANG! Please, what a joke! Chaos never leads to order. Order can only come from careful planning and meticulous precision, which God has certainly accomplished. It is man that steals, kills, and destroys as Satan wants them too (John 10:10).
So let's get this straight. The Universe is a big, complex place that doesn't show the slightest evidence of actual design or intervention. You assert without proof that it must have been created, even though all the laws of nature based on observation are CONSERVATION LAWS that suggest that NOTHING has ever been created in the history of the Universe itself. Everything that you think of as being the "creation" of something is just preexisting stuff moving around. You have never observed one single thin
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Truth, justice, and The American Way are not science either. Yet these irrational things have more impact on your life than the tiny little subset of the universe that is all that science can ever know.
I do not disagree with you, but I find that your statement has no inherent value and that you are contributing nothing worthwhile to the conversation.
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Re:Jesus saves (Score:5, Funny)
There are none who do not believe in Pink Unicorns! How can any man say, who has not travelled to the farthest end of the Universe, that Pink Unicorns do not exist? Indeed, anybody who says so secretly is claiming to BE a Pink Unicorn. Pink Unicorns hate fags and commies so you -- I'm talking to you, you apostatic Pink Unicorn believer wearing the halloween costume -- need to pass draconian laws punishing commies and let us arrest fags and send them against their will to a special school that will teach them to find only members of the opposite sex attractive, and then only within the bounds of holy matrimony. I'm talking about you, Robert De Niro and you, Billy Joel! You claim not to believe in the Pink One's Perfect Horn, but deep in your heart you have seen its Cornute Majesty as the twist in every spiral galaxy, especially those that radiate high in the Pink part of the spectrum.
DON'T BLAME ME, you anunicornists, if the great Pink Unicorn shows up one day and impales you on its Horn of Perfect Justice! It could happen! Seriously! You haven't BEEN to Alpha Centauri -- it could be liberally populated with Pink Unicorns for all you know! I have had a Holy Vision of Pink, and I Know! So sayeth the prophets, and everybody knows that people who wrote stuff down LONG AGO are always right and never made mistakes! Only that liberal commie activity known as "science" makes mistakes -- imagine, insisting on POSITIVE evidence for the existence of Pink Unicorns when the Holy Fathers among the ancients speak of "walking with the Unicorn" and tell of the many miracles performed by the Pinkest of them all. What more evidence do you need?
Oh, and by the way, pay no attention to the deluded fools in that cult over there who claim that Unicorns are not Pink, they are really Blue. Or that group -- Purple Dinosaurs (that walked with men back before the flood) are clearly right up there with Winkie-Tink, thinly disguised Faggery intended to corrupt the morals of our children and distract them from Pink! Besides, they have no evidence to back their claim, as clearly THEIR ancient prophets were just smelly old men who are lying to you to corrupt you. But the one true Pink Unicorn knows all and sees all, peering out from behind every rock and stone in the Universe, and...
What's that? Take your hands off of me, sir! I protest! Well of course I stopped taking that medicine! It was distracting me from my holy duty! I could no longer see Pink when I closed my eyes, my mortal body was in danger of being Holed and the prophets say that sinners who turn their back on the Unicorn will be trampled under hoof for all eternity! Let me go!
I will not be silenced! No! Don't put me in there! No! No! Not the needle! The TRUTH will soon be known! BEWARE, you foul, white jacketed sinners, the Unicorn that comes to trample you and everyone you love in the ni
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You mean to say Pink Unicorns COULD exist -- if we build them -- and I agree. And they could exist even if we don't. For a long time, Europeans thought that there were no black swans because they'd never seen any. They were wrong -- they just hadn't looked in the right place. Now we would say that there are no paisley dayglo multicolored swans because we've looked everywhere that one could reasonably find swans, we've catalogued swan DNA, we understand the process of evolution that gave rise to swans an