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I'm not sure where to report this, maybe one could guide it along the correct channels: To sort the list after values with 10x^6 and 5.6 is not only faulty and confusing but renders it as a tool useless. The Javascript sorting-code should be fixed to accept values with exponents (be it base 2, e, 10 or any other) and real-number points. —Preceding unsigned comment added by GENtLe ( talk • contribs) 23:14, 29 January 2008 (UTC)
Has Stern himself used this term in his papers? From everything I've read by him he supports the concept but think's the IAU definition has lousy wording. If he hasn't, this needs to be made clear in the article. The Enlightened 05:14, 13 October 2006 (UTC)
I'm not sure where to put this, but there seems to be an extraneous bit of information on the page with the line "HE WAS BORN IN MICHIGAN IN 1946" near the top of the page.
24.159.236.28 06:57, 25 October 2006 (UTC) Mentor397
This article is accumilating various pastel-shaded boxes at the top that request work be done, but I can't easily tell exactly what it is that's wrong with the article. Why does this article need the attention of an expert? What sort of information on this subject would be "more general"? Which bits of the article are confusing to some readers? Bryan Derksen 17:56, 11 April 2007 (UTC)
From the edit history:
As written, the article notes that bodies with a Stern-Levinson parameter Λ > 1 have "cleared a substantial fraction of small bodies out of [their] orbital neighborhood[s]", and implicitly those bodies with Λ < 1 have not "cleared the neighbourhood." Yet the table lists values of Λ normalized to the value for Earth, although the cited Soter article lists the actual (approximate) values for Λ in Table 1. To me, this seems like a disconnect between the text of the article and the table, and confusing for the lay reader. I would rather just be able to see at a glance whether the Stern-Levinson parameter for a body is less than or greater than 1, which is the important distinction, rather than the value of the parameter relative to Earth's value. This is why I added a note giving the value of ΛE and the values of Λ for the other 10 bodies relative to 1. Can someone explain why the table in this article (and associated tables in related articles) uses Λ/ΛE, rather than simply Λ? Spiderboy12 14:15, 19 September 2007 (UTC)
Perhaps this is in order to make the article more clear for the casual reader? Even if they are unfamiliar with this concept and just want to do some light reading, Λ/ΛE gives a frame of reference for this value, as opposed to some arbitrary number that they know little about.
204.85.24.5 (
talk) 18:42, 15 February 2008 (UTC)
A related request, not strictly applicable to this page. Please could somebody with appropriate expertise, so not me, write an article defining and explaining the Stern–Levison parameter. It seems to be really good discriminant between planets and smaller things, but what is it? JDAWiseman ( talk) 11:57, 1 October 2013 (UTC)
Further to previous request, the Stern–Levison paper is at boulder.swri.edu/~hal/PDF/planet_def.pdf and was quite helpful (though the explanation of the equations assumed more expertise than should Wikipedia). JDAWiseman ( talk) 15:56, 9 February 2014 (UTC)
This name is a bit cnfusing if you don't know what it should be about. A correct name should have "". Nergaal ( talk) 03:59, 28 January 2008 (UTC)
Okay, this article has now been around a while. Re this part:
...will someone please take the time to define k? Or has IAU become a secret society and this is a secret that we're not allowed to know? —Preceding unsigned comment added by 204.4.13.72 ( talk) 22:27, 11 February 2008 (UTC)
I recommend adding information about Makemake (dwarf planet) to the data table in the article showing planets and dwarf planets. (I'd have done it myself except I don't have the corresponding numbers.) 63.111.163.13 ( talk) 21:37, 16 July 2008 (UTC)
If "k" is "approximately constant", then what is its value? It could change the outcome of the equation radically if it is greater than or less than 1. Serendi pod ous 07:47, 8 August 2008 (UTC)
Haumea_(dwarf_planet) needs to be added to the "In the Solar System" table, since it's now been officially declared a "dwarf planet". Dave ( talk) 18:24, 23 September 2008 (UTC)
According to the table, Lambda_Eris < Lambda_Pluto, but Lambda_Eris/Lambda_E > Lambda_Pluto/Lambda_E
Did the IAU ever get around to defining the term, "clearing the neighborhood", say at their 2009 meeting? As I recall, that was left undefined in 2006. -- KarlHallowell ( talk) 20:48, 8 December 2009 (UTC)
Consider the Saturnian moons Tethys, Telesto and Calypso. These moons share an orbit, where Telesto and Calypso lie in the 4th and 5th Lagrange points of Tethys. Now imagine we find a group of extrasolar planets of Earthlike (or even larger) size that orbit their star in a similar way, which we will almost certainly observe someday. Then doesn't this "clearing the neighborhood" business become a bunch of BS? ChessA4 ( talk) 03:12, 24 April 2010 (UTC)
What does "cheese" mean in the table? At first glance, this appears to be vandalism, as it's not explained elsewhere in the article, but it's been in the article now for a couple of years. - BilCat ( talk) 00:15, 12 May 2011 (UTC)
The planetary discriminant for Ceres is given as 0.33. Is this really the correct number? Ceres has about one third of the mass of the asteroid belt, but the definition of "planetary discriminant" has mu= mass(Ceres) / mass(Ceres-crossers). Which means if mu = 0.33, then the mass of Ceres-crossers would be 3 times that of Ceres, and not all of the asteroids in the belt cross Ceres either. So, was the discriminant actually computed (meaning there are many Ceres-crossers outside the belt), or just copied in? Ambi Valent ( talk) 09:53, 7 October 2012 (UTC)
Can someone get rid of the garbage about überplanet and unterplanet? — Preceding unsigned comment added by 112.118.143.28 ( talk) 08:19, 15 December 2013 (UTC)
The article said Most planetary scientists understand "clearing the neighborhood" to refer to an object being the dominant mass in its vicinity, for instance Earth being many times more massive than all of the NEAs combined, and Neptune "dwarfing" Pluto and the rest of the KBOs.
Neptune has not cleared its neighborhood because it dwarfs Pluto and the KBOs. Pluto is disregarded because its orbit prevents it from colliding with Neptune, and Neptune is not a KBO in any case. Saros136 ( talk) 15:12, 5 October 2014 (UTC)
How do you define orbital period if say the Sun is moving around the Galaxy, the Galaxy it self is moving and even where the Earth moves away from the Sun is completely different during each "orbital period."
You would say dominate body in its orbit, but is it? The dominate thing in any planet's orbit is not the planet, but the dark energy and dark matter in its orbit.
And wouldn't it make more sense to have true definition rather than arbitrary ones for the convenience of the market place, rather than actual science? Hmm?
Think about this? Is the sun, the center of our universe? It is not, then we do we morph our understanding of space to fit the criteria as though it is for an untrue view of our cosmos as a simple means to satisfy our market? Science and the market should be two separate things. We shouldn't be morphing our understanding of reality just to make a quick buck. — Preceding unsigned comment added by 70.160.104.223 ( talk) 17:47, 7 November 2014 (UTC)
Stupid laypersons question. As I understand it, Trojans (masses at Lagrange points 4 & 5) share the same orbit with the body under consideration for planethood, yet are stable so would not be cleared. So clearing the neighborhood, as I understand the definition, would mean Jupiter was a dwarf planet as it has a shared orbit (co-orbital configuration). Could the article be made clearer so I can see where my thinking is going wrong, please? — Preceding unsigned comment added by 31.50.82.206 ( talk) 12:53, 15 July 2015 (UTC)
Would someone be able to add the physical units to this equation, so that the result becomes dimensionless, as seen in the remainder of the article. Alternatively, what is the approximate value (including dimensions) of k. Tomeasy T C 05:50, 16 September 2015 (UTC)
Astronomer Margot proposed a planet discriminant Π which is proportional to M/(a^(9/8)), which means it falls steeper towards 1 with growing distance than Stern-Levison's scattering parameter. Margot discussed a looser variant (planets needs to clear just its feeding area) and a stricter variant (stability criteria, observed spacing of exoplanets). For Mercury, these would mean it could only successfully clear an orbit up to 29 AU from the Sun (loose) or 18 AU (strict); for Mars, the values would be 53 AU (loose) and 32 AU (strict). Should Margot's discriminant be added to the article and the table? Ambi Valent ( talk) 04:13, 1 December 2015 (UTC)
I think Planet Nine should be added.
I have placed an unbalanced tag on the Disagreement section of the article as it is plainly written from the point of view of someone opposed to the IAU definition; it gives no arguments in favour of that definition and gives little weight to the views of its proponents.
I question whether this section should be in the article at all. It has no bearing on the meaning of 'clearing the neighbourhood' but instead is concerned with whether or not 'clearing the neighbourhood' should be a criteria in the definition of a planet. This should really be covered in articles relating to such a definition. All that is needed here is a paragraph noting the dispute and linking to the relevant pages. Cuddlyopedia ( talk) 02:53, 27 January 2016 (UTC)
Hello everybody,
I see your point that it overwhelmed the article, but I spent a whole day researching it and I tried to write it from a neutral perspective, so it was not a "rant". I gave arguments for the other side, though apparently not with balance so I will try to improve that. I also agree it probably should be a separate article.
However, the current section is itself not neutral and needs improvement. The main problem is that it mischaracterizes the disagreement and I was trying to fix that. The article brings up Stern's disagreement with declassifying Pluto, so it already puts the disagreement into the context of the planet definition. I didn't add that, I only tried to balance it. A more substantial part of the disagreement focuses on how "clearing the neighborhood" is an extrinsic property whereas some people say we should use only intrinsic properties for classification. That disagreement is completely relevant to an article about clearing neighborhoods, especially one that has a "disagreement" section, doubly so when that section puts it into the context of planet definitions. Per the neutral POV policy on balancing aspects: "An article should not give undue weight to any aspects of the subject but should strive to treat each aspect with a weight appropriate to the weight of that aspect in the body of reliable sources on the subject." I provided many references from reliable sources to show that this other issue is part of the disagreement on "clearing neighborhoods". The article should at least name all of the disagreements (or else it should name none of them) and then it should provide a link to an article that deals with all of them in full.
Also, since this section cites only Stern, it communicates the unbalanced idea that only one significant person is disagreeing, which undermines that perspective (in reality 400 planetary scientists signed a petition in 2006 to protest it, and the leadership of the AAS Division of Planetary Sciences criticized it, as did other significant scientists). And BTW, the reason it hasn't been brought up in later IAU meetings is only because planetary scientists know it would fail in another vote because the non-geoscience astronomers favor the present definition, in part out of a desire to move on. The fact that it hasn't been raised in another IAU meeting isn't relevant to this discussion. I gave references for all these people disagreeing with various aspects of clearing the neighborhood.
The article also violates neutral perspective in the way Stern's statements are uncharitably characterized. When Stern said that not even Earth has cleared its orbit and therefore fails the IAU definition, that isn't a "shift" from his 2001 paper in the least, since the whole point of that paper was to propose a specific metric that the Earth does not fail. By interpreting Stern in this uncharitable way, making it sound as though he shifted his arguments after Pluto was declassified (which suggests to the average reader that Stern's arguments derive from bias rather than from reasoning), the article is taking sides.
I agree in retrospect that some of the other disagreements I had included are better in an article on the overall planet/DP controversy since they are not specifically about the efficacy of clearing orbits or the valid application of clearing orbits.
If my edit failed to achieve balance then then it should have been corrected (and made smaller), not removed. Reverting it violates the intent of this policy:
As a general rule, do not remove sourced information from the encyclopedia solely on the grounds that it seems biased. Instead, try to rewrite the passage or section to achieve a more neutral tone.
I provided sources for everything that I wrote and the text will give readers a much better understanding of the nature of the disagreements. Calling what I wrote a "rant" to justify deleting it wholesale violates the Wikipedia policy to assume good faith. Furthermore, I feel it violates the intent of the "do not bite the newcomers" guideline. Although I'm not a newbie to Wikipedia, I am a newbie in editing this article. Wholesale deletion of an entire day of research made to improve the article isn't very welcoming.
I request JeanLucMargot to let me know what he sees as factually incorrect. Everything I wrote was reporting what other scientists have said as part of their disagreement, and they were all sourced, so unless I misquoted them then it couldn't have been factually incorrect, by definition. Their opinions are what they are. If there is something I am missing here please let me know what it is so when I work on the sub-article (trying to achieve more balance) and on this article (keeping what you said above in mind) then I can avoid any factual errors. Sanddune777 ( talk) 01:46, 28 January 2016 (UTC)
Sanddune777: I'm sorry that a day's research got deleted; but the results of the research are simply in the wrong place. Hopefully, you can utilise the research somewhere more appropriate. What's needed here is a relatively short note that the controversy over 'clearing the neighbourhood' is not so much over the concept itself but the use of the concept in the definition of a planet and to the imprecision of the concept in the IAU definition. However, I do agree that the current section is itself somewhat not neutral and could be improved. If no-one objects, I'll give it a go in the next day or so. Cuddlyopedia ( talk) 07:42, 28 January 2016 (UTC)
The reporter then summarizes Stern's second argument where he says that major planets also fail to absolutely clear their zones, and it ends with another quote from Stern, "If Neptune had cleared its zone, Pluto wouldn't be there." It is this second argument (not the first one) that deals with the incompleteness of clearing zones, and Stern only says "the actual definition" (its wording) is "inconsistent" (not impossible). It is his first argument that contains the word "impossible", but there he is discussing the meaningfulness of intrinsic definitions, not the absoluteness of clearing zones. His illustration of separating classes of people makes this point. He isn't saying it is impossible to create sorting criteria that put people into groups; he is saying that people are intrinsically people despite how we group them, and it is impossible to make it otherwise with a definition. This is the thrust of the word "impossible" in context. Also, please looking at Stern's quote more carefully, because he didn't say it is impossible to put a dividing line between dwarf planets and major planets (unter- versus uber-). Rather, he said it is impossible to put a dividing line between dwarf planets and planets. He believes dwarf planets are still intrinsically planets, a subcategory of planets. He is saying it is impossible to make dwarf planets not be a subcategory of planets because they are still intrinsically the same types of objects. So here again there is no self-contradiction. I searched the web some months ago and found only one obscure bulletin board where somebody made a similar claim that Stern has contradicted himself. Today, I was unable to find anything making this claim. It certainly isn't in the news anywhere, and so it shouldn't be made into an issue here. We can report controversies but we can't create them where they don't exist, and Stern supposedly contradicting himself is not a notable controversy outside of this discussion. One way to change this article is to take the focus off Stern and instead quote several people saying the IAU's current definition is vague and should be changed or should not be changed based upon how we apply it in light of these discriminants. I think that would be a more meaningful summary of the public discussion related to this concept of "Clearing the Neighbourhood". Sanddune777 ( talk) 19:20, 20 March 2016 (UTC)It's an awful definition; it's sloppy science and it would never pass peer review - for two reasons. Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets. It's as if we declared people not people for some arbitrary reason, like 'they tend to live in groups'. Secondly, the actual definition is even worse, because it's inconsistent.
Notice that he directly acknowledges that orbit clearing is accomplished for six of these bodies but not for the other three, and that we can tell which bodies fall into each of the two categories, that we can even predict it ahead of time, and that we could form a classification system based on it (although he argues it would be an unhelpful classification system for people who study the bodies themselves). If Alan had indeed switched his views since his 2000 paper then he could not have given this recent quote. On the other hand, when he says at other times that not even Earth has "cleared its orbit", he isn't contradicting what he said in the above, recent quote; he is just lampooning the IAU's vague wording because taken literally it implies an absoluteness that no planet ever accomplishes. (By the way, Mike Brown has also used lampooning to make an argument opposing Alan.)Suppose that in your mind, you created a solar system exactly like ours, except at each of the orbits of the nine classical planets, you put an Earth. As you go further outward in the solar system, you cross a boundary where Earth is no longer able to clear its zone, because the zone is too big. It turns out that happens around the orbit of Neptune, maybe Uranus. So you would have nine identical objects, six of which you would call a planet and three of which you would not. They're identical in every respect except where they are.( http://www.space.com/12710-pluto-defender-alan-stern-dwarf-planet-interview.html)
I see your point that the resolution's footnote implies clearing isn't absolute and therefore Alan's lampooning (where he criticizes the lack of a specific metric by saying its absence implies absolute clearing) can be criticized for that reason. But putting this in Wikipedia would still be synthesis because there are no sources that go through that argument as you have done here. I don't see any sources saying, "The IAU's definition as-worded is adequate because the footnote clears up the vagueness." If there were, then that could be placed against Alan's argument as a disagreement. The IAU resolution is a citeable source about itself, but it is not a source for the derivative arguments. Presently I see several people (including yourself JeanLucMargot) saying to the press that the definition as-worded is not adequate, but I don't see anybody saying to the press or in published papers that Alan's particular way of criticizing its inadequacy is wrong.
Note that Mike Brown has also used lampooning when he criticized an alternative proposal, the one supported by the AAU's DPS. Mike says it would have included more than 53 bodies as planets, and thus it would have been a "no ice ball left behind" policy. This is not technically correct and could have been criticized since the geophysical definition of a planet leaves the vast majority of ice balls behind, those that aren't in hydrostatic equilibrium. The point of lampooning is not to be technically perfect, but to bring some inadequacy into sharp focus so people can grasp it, perhaps using hyperbole as Mike did. Attacking Mike Brown's "no ice ball left behind" statement on grounds that it technically misrepresented the DPS proposal would miss the point. Similarly, attacking this one of Alan's arguments that it isn't technically correct or complete for whatever reason is missing the point. The point is that the IAU definition fails to provide a measurable criterion, something everybody agrees with. Sanddune777 ( talk) 15:42, 4 April 2016 (UTC)
I asked Alan to respond to the criticism that he contradicted himself and I just got his response. Here is my question to him.
When you point out that not even Earth or Neptune have cleared their orbits, does that mean you no longer believe it’s possible to define orbit clearing in a precise way as you did in 2001? Or are you simply pointing out that the IAU definition failed to be specific?
Here is his response:
Fair question. About the point below, I am saying as I have long said, that the IAU’s statement on orbit clearing was sloppy. It speaks to cleared zones, not the ability to clear zones, and as we know, no planet’s orbit in this solar system is cleared (else there would be no NEAs, no trojans of Mars or the giant planets, no Plutinos in MMRs that cross Neptune’s orbit, etc.), this is in part because there are stable niches (1:1 librators as one example) and because there are always new sources of objects injected once a zone clears. The point of this particular criticism is to highlight the rushed and sloppy nature of the IAU definition, adopted in violation of its own rules, in the rush to get out of Prague. Science should not be sloppy, and scientists should not respect definitions with such clearly sloppy, flawed language.
This does not contradict his 2001 paper, and it does not imply that orbit clearing must be impeccable to be part of a dynamical definition. He is just criticizing the sloppy language that resulted from a rushed and flawed process. Obviously he knows we can define dwarf planets. Sanddune777 ( talk) 18:27, 4 April 2016 (UTC)
In the Margot's Π section it is stated: "Using Solar masses for the unit of mass for the star, Earth masses for the unit of mass for the planet-candidate, and AU for the unit of distance for the semi-major axis, k = 833." For Earth, these are all 1, so the formula for Π given reduces to Π=k and therefore Π should be 833 for Earth. However, in the table, taken from Margot's paper, the value for Earth is given as 810. Thus suggests the figure for k given in the article is incorrect. Comments? Cuddlyopedia ( talk) 08:04, 30 January 2016 (UTC)
Glad I wasn't seeing things! Great work on the table by the way. :) Whilst writing: In the table, I notice that for all the planets Λ>Π whereas for all the dwarf planets Λ<Π. Does this always hold, or at least when either/both value is not close to 1? If so, might be worth noting that unless the object is near the boundary it's only necessary to work out one of these, as the other follows. Cuddlyopedia ( talk) 13:41, 31 January 2016 (UTC)
While I am not arrogant enough to change the spelling to the American form (which appears several times both in the article and on this talk page), is there some historical basis for including the superfluous British 'u' in the title? Is that naming (and other) history worth mentioning in the article?
I wonder how the IAU defined the "neighbourhood" or "region" of a planet. Is it half an astronomical unit within the planet's center? Or 10.000 miles? 100.000 miles? 100.000 nautical miles? Since the IAU didn't concretize that the definition of "clearing the neighbourhood" is too vague to be taken seriously. And if Pluto and Eris were no planets according to that definition, so wouldn't be Earth, Mars or Jupiter. Complete nonsense which has nothing to do with whether a body is a planet or not. 212.186.7.232 ( talk) 09:18, 31 March 2019 (UTC)
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Clearing the neighbourhood article. This is not a forum for general discussion of the article's subject. |
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Clearing the neighbourhood received a peer review by Wikipedia editors, which is now archived. It may contain ideas you can use to improve this article. |
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I'm not sure where to report this, maybe one could guide it along the correct channels: To sort the list after values with 10x^6 and 5.6 is not only faulty and confusing but renders it as a tool useless. The Javascript sorting-code should be fixed to accept values with exponents (be it base 2, e, 10 or any other) and real-number points. —Preceding unsigned comment added by GENtLe ( talk • contribs) 23:14, 29 January 2008 (UTC)
Has Stern himself used this term in his papers? From everything I've read by him he supports the concept but think's the IAU definition has lousy wording. If he hasn't, this needs to be made clear in the article. The Enlightened 05:14, 13 October 2006 (UTC)
I'm not sure where to put this, but there seems to be an extraneous bit of information on the page with the line "HE WAS BORN IN MICHIGAN IN 1946" near the top of the page.
24.159.236.28 06:57, 25 October 2006 (UTC) Mentor397
This article is accumilating various pastel-shaded boxes at the top that request work be done, but I can't easily tell exactly what it is that's wrong with the article. Why does this article need the attention of an expert? What sort of information on this subject would be "more general"? Which bits of the article are confusing to some readers? Bryan Derksen 17:56, 11 April 2007 (UTC)
From the edit history:
As written, the article notes that bodies with a Stern-Levinson parameter Λ > 1 have "cleared a substantial fraction of small bodies out of [their] orbital neighborhood[s]", and implicitly those bodies with Λ < 1 have not "cleared the neighbourhood." Yet the table lists values of Λ normalized to the value for Earth, although the cited Soter article lists the actual (approximate) values for Λ in Table 1. To me, this seems like a disconnect between the text of the article and the table, and confusing for the lay reader. I would rather just be able to see at a glance whether the Stern-Levinson parameter for a body is less than or greater than 1, which is the important distinction, rather than the value of the parameter relative to Earth's value. This is why I added a note giving the value of ΛE and the values of Λ for the other 10 bodies relative to 1. Can someone explain why the table in this article (and associated tables in related articles) uses Λ/ΛE, rather than simply Λ? Spiderboy12 14:15, 19 September 2007 (UTC)
Perhaps this is in order to make the article more clear for the casual reader? Even if they are unfamiliar with this concept and just want to do some light reading, Λ/ΛE gives a frame of reference for this value, as opposed to some arbitrary number that they know little about.
204.85.24.5 (
talk) 18:42, 15 February 2008 (UTC)
A related request, not strictly applicable to this page. Please could somebody with appropriate expertise, so not me, write an article defining and explaining the Stern–Levison parameter. It seems to be really good discriminant between planets and smaller things, but what is it? JDAWiseman ( talk) 11:57, 1 October 2013 (UTC)
Further to previous request, the Stern–Levison paper is at boulder.swri.edu/~hal/PDF/planet_def.pdf and was quite helpful (though the explanation of the equations assumed more expertise than should Wikipedia). JDAWiseman ( talk) 15:56, 9 February 2014 (UTC)
This name is a bit cnfusing if you don't know what it should be about. A correct name should have "". Nergaal ( talk) 03:59, 28 January 2008 (UTC)
Okay, this article has now been around a while. Re this part:
...will someone please take the time to define k? Or has IAU become a secret society and this is a secret that we're not allowed to know? —Preceding unsigned comment added by 204.4.13.72 ( talk) 22:27, 11 February 2008 (UTC)
I recommend adding information about Makemake (dwarf planet) to the data table in the article showing planets and dwarf planets. (I'd have done it myself except I don't have the corresponding numbers.) 63.111.163.13 ( talk) 21:37, 16 July 2008 (UTC)
If "k" is "approximately constant", then what is its value? It could change the outcome of the equation radically if it is greater than or less than 1. Serendi pod ous 07:47, 8 August 2008 (UTC)
Haumea_(dwarf_planet) needs to be added to the "In the Solar System" table, since it's now been officially declared a "dwarf planet". Dave ( talk) 18:24, 23 September 2008 (UTC)
According to the table, Lambda_Eris < Lambda_Pluto, but Lambda_Eris/Lambda_E > Lambda_Pluto/Lambda_E
Did the IAU ever get around to defining the term, "clearing the neighborhood", say at their 2009 meeting? As I recall, that was left undefined in 2006. -- KarlHallowell ( talk) 20:48, 8 December 2009 (UTC)
Consider the Saturnian moons Tethys, Telesto and Calypso. These moons share an orbit, where Telesto and Calypso lie in the 4th and 5th Lagrange points of Tethys. Now imagine we find a group of extrasolar planets of Earthlike (or even larger) size that orbit their star in a similar way, which we will almost certainly observe someday. Then doesn't this "clearing the neighborhood" business become a bunch of BS? ChessA4 ( talk) 03:12, 24 April 2010 (UTC)
What does "cheese" mean in the table? At first glance, this appears to be vandalism, as it's not explained elsewhere in the article, but it's been in the article now for a couple of years. - BilCat ( talk) 00:15, 12 May 2011 (UTC)
The planetary discriminant for Ceres is given as 0.33. Is this really the correct number? Ceres has about one third of the mass of the asteroid belt, but the definition of "planetary discriminant" has mu= mass(Ceres) / mass(Ceres-crossers). Which means if mu = 0.33, then the mass of Ceres-crossers would be 3 times that of Ceres, and not all of the asteroids in the belt cross Ceres either. So, was the discriminant actually computed (meaning there are many Ceres-crossers outside the belt), or just copied in? Ambi Valent ( talk) 09:53, 7 October 2012 (UTC)
Can someone get rid of the garbage about überplanet and unterplanet? — Preceding unsigned comment added by 112.118.143.28 ( talk) 08:19, 15 December 2013 (UTC)
The article said Most planetary scientists understand "clearing the neighborhood" to refer to an object being the dominant mass in its vicinity, for instance Earth being many times more massive than all of the NEAs combined, and Neptune "dwarfing" Pluto and the rest of the KBOs.
Neptune has not cleared its neighborhood because it dwarfs Pluto and the KBOs. Pluto is disregarded because its orbit prevents it from colliding with Neptune, and Neptune is not a KBO in any case. Saros136 ( talk) 15:12, 5 October 2014 (UTC)
How do you define orbital period if say the Sun is moving around the Galaxy, the Galaxy it self is moving and even where the Earth moves away from the Sun is completely different during each "orbital period."
You would say dominate body in its orbit, but is it? The dominate thing in any planet's orbit is not the planet, but the dark energy and dark matter in its orbit.
And wouldn't it make more sense to have true definition rather than arbitrary ones for the convenience of the market place, rather than actual science? Hmm?
Think about this? Is the sun, the center of our universe? It is not, then we do we morph our understanding of space to fit the criteria as though it is for an untrue view of our cosmos as a simple means to satisfy our market? Science and the market should be two separate things. We shouldn't be morphing our understanding of reality just to make a quick buck. — Preceding unsigned comment added by 70.160.104.223 ( talk) 17:47, 7 November 2014 (UTC)
Stupid laypersons question. As I understand it, Trojans (masses at Lagrange points 4 & 5) share the same orbit with the body under consideration for planethood, yet are stable so would not be cleared. So clearing the neighborhood, as I understand the definition, would mean Jupiter was a dwarf planet as it has a shared orbit (co-orbital configuration). Could the article be made clearer so I can see where my thinking is going wrong, please? — Preceding unsigned comment added by 31.50.82.206 ( talk) 12:53, 15 July 2015 (UTC)
Would someone be able to add the physical units to this equation, so that the result becomes dimensionless, as seen in the remainder of the article. Alternatively, what is the approximate value (including dimensions) of k. Tomeasy T C 05:50, 16 September 2015 (UTC)
Astronomer Margot proposed a planet discriminant Π which is proportional to M/(a^(9/8)), which means it falls steeper towards 1 with growing distance than Stern-Levison's scattering parameter. Margot discussed a looser variant (planets needs to clear just its feeding area) and a stricter variant (stability criteria, observed spacing of exoplanets). For Mercury, these would mean it could only successfully clear an orbit up to 29 AU from the Sun (loose) or 18 AU (strict); for Mars, the values would be 53 AU (loose) and 32 AU (strict). Should Margot's discriminant be added to the article and the table? Ambi Valent ( talk) 04:13, 1 December 2015 (UTC)
I think Planet Nine should be added.
I have placed an unbalanced tag on the Disagreement section of the article as it is plainly written from the point of view of someone opposed to the IAU definition; it gives no arguments in favour of that definition and gives little weight to the views of its proponents.
I question whether this section should be in the article at all. It has no bearing on the meaning of 'clearing the neighbourhood' but instead is concerned with whether or not 'clearing the neighbourhood' should be a criteria in the definition of a planet. This should really be covered in articles relating to such a definition. All that is needed here is a paragraph noting the dispute and linking to the relevant pages. Cuddlyopedia ( talk) 02:53, 27 January 2016 (UTC)
Hello everybody,
I see your point that it overwhelmed the article, but I spent a whole day researching it and I tried to write it from a neutral perspective, so it was not a "rant". I gave arguments for the other side, though apparently not with balance so I will try to improve that. I also agree it probably should be a separate article.
However, the current section is itself not neutral and needs improvement. The main problem is that it mischaracterizes the disagreement and I was trying to fix that. The article brings up Stern's disagreement with declassifying Pluto, so it already puts the disagreement into the context of the planet definition. I didn't add that, I only tried to balance it. A more substantial part of the disagreement focuses on how "clearing the neighborhood" is an extrinsic property whereas some people say we should use only intrinsic properties for classification. That disagreement is completely relevant to an article about clearing neighborhoods, especially one that has a "disagreement" section, doubly so when that section puts it into the context of planet definitions. Per the neutral POV policy on balancing aspects: "An article should not give undue weight to any aspects of the subject but should strive to treat each aspect with a weight appropriate to the weight of that aspect in the body of reliable sources on the subject." I provided many references from reliable sources to show that this other issue is part of the disagreement on "clearing neighborhoods". The article should at least name all of the disagreements (or else it should name none of them) and then it should provide a link to an article that deals with all of them in full.
Also, since this section cites only Stern, it communicates the unbalanced idea that only one significant person is disagreeing, which undermines that perspective (in reality 400 planetary scientists signed a petition in 2006 to protest it, and the leadership of the AAS Division of Planetary Sciences criticized it, as did other significant scientists). And BTW, the reason it hasn't been brought up in later IAU meetings is only because planetary scientists know it would fail in another vote because the non-geoscience astronomers favor the present definition, in part out of a desire to move on. The fact that it hasn't been raised in another IAU meeting isn't relevant to this discussion. I gave references for all these people disagreeing with various aspects of clearing the neighborhood.
The article also violates neutral perspective in the way Stern's statements are uncharitably characterized. When Stern said that not even Earth has cleared its orbit and therefore fails the IAU definition, that isn't a "shift" from his 2001 paper in the least, since the whole point of that paper was to propose a specific metric that the Earth does not fail. By interpreting Stern in this uncharitable way, making it sound as though he shifted his arguments after Pluto was declassified (which suggests to the average reader that Stern's arguments derive from bias rather than from reasoning), the article is taking sides.
I agree in retrospect that some of the other disagreements I had included are better in an article on the overall planet/DP controversy since they are not specifically about the efficacy of clearing orbits or the valid application of clearing orbits.
If my edit failed to achieve balance then then it should have been corrected (and made smaller), not removed. Reverting it violates the intent of this policy:
As a general rule, do not remove sourced information from the encyclopedia solely on the grounds that it seems biased. Instead, try to rewrite the passage or section to achieve a more neutral tone.
I provided sources for everything that I wrote and the text will give readers a much better understanding of the nature of the disagreements. Calling what I wrote a "rant" to justify deleting it wholesale violates the Wikipedia policy to assume good faith. Furthermore, I feel it violates the intent of the "do not bite the newcomers" guideline. Although I'm not a newbie to Wikipedia, I am a newbie in editing this article. Wholesale deletion of an entire day of research made to improve the article isn't very welcoming.
I request JeanLucMargot to let me know what he sees as factually incorrect. Everything I wrote was reporting what other scientists have said as part of their disagreement, and they were all sourced, so unless I misquoted them then it couldn't have been factually incorrect, by definition. Their opinions are what they are. If there is something I am missing here please let me know what it is so when I work on the sub-article (trying to achieve more balance) and on this article (keeping what you said above in mind) then I can avoid any factual errors. Sanddune777 ( talk) 01:46, 28 January 2016 (UTC)
Sanddune777: I'm sorry that a day's research got deleted; but the results of the research are simply in the wrong place. Hopefully, you can utilise the research somewhere more appropriate. What's needed here is a relatively short note that the controversy over 'clearing the neighbourhood' is not so much over the concept itself but the use of the concept in the definition of a planet and to the imprecision of the concept in the IAU definition. However, I do agree that the current section is itself somewhat not neutral and could be improved. If no-one objects, I'll give it a go in the next day or so. Cuddlyopedia ( talk) 07:42, 28 January 2016 (UTC)
The reporter then summarizes Stern's second argument where he says that major planets also fail to absolutely clear their zones, and it ends with another quote from Stern, "If Neptune had cleared its zone, Pluto wouldn't be there." It is this second argument (not the first one) that deals with the incompleteness of clearing zones, and Stern only says "the actual definition" (its wording) is "inconsistent" (not impossible). It is his first argument that contains the word "impossible", but there he is discussing the meaningfulness of intrinsic definitions, not the absoluteness of clearing zones. His illustration of separating classes of people makes this point. He isn't saying it is impossible to create sorting criteria that put people into groups; he is saying that people are intrinsically people despite how we group them, and it is impossible to make it otherwise with a definition. This is the thrust of the word "impossible" in context. Also, please looking at Stern's quote more carefully, because he didn't say it is impossible to put a dividing line between dwarf planets and major planets (unter- versus uber-). Rather, he said it is impossible to put a dividing line between dwarf planets and planets. He believes dwarf planets are still intrinsically planets, a subcategory of planets. He is saying it is impossible to make dwarf planets not be a subcategory of planets because they are still intrinsically the same types of objects. So here again there is no self-contradiction. I searched the web some months ago and found only one obscure bulletin board where somebody made a similar claim that Stern has contradicted himself. Today, I was unable to find anything making this claim. It certainly isn't in the news anywhere, and so it shouldn't be made into an issue here. We can report controversies but we can't create them where they don't exist, and Stern supposedly contradicting himself is not a notable controversy outside of this discussion. One way to change this article is to take the focus off Stern and instead quote several people saying the IAU's current definition is vague and should be changed or should not be changed based upon how we apply it in light of these discriminants. I think that would be a more meaningful summary of the public discussion related to this concept of "Clearing the Neighbourhood". Sanddune777 ( talk) 19:20, 20 March 2016 (UTC)It's an awful definition; it's sloppy science and it would never pass peer review - for two reasons. Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets. It's as if we declared people not people for some arbitrary reason, like 'they tend to live in groups'. Secondly, the actual definition is even worse, because it's inconsistent.
Notice that he directly acknowledges that orbit clearing is accomplished for six of these bodies but not for the other three, and that we can tell which bodies fall into each of the two categories, that we can even predict it ahead of time, and that we could form a classification system based on it (although he argues it would be an unhelpful classification system for people who study the bodies themselves). If Alan had indeed switched his views since his 2000 paper then he could not have given this recent quote. On the other hand, when he says at other times that not even Earth has "cleared its orbit", he isn't contradicting what he said in the above, recent quote; he is just lampooning the IAU's vague wording because taken literally it implies an absoluteness that no planet ever accomplishes. (By the way, Mike Brown has also used lampooning to make an argument opposing Alan.)Suppose that in your mind, you created a solar system exactly like ours, except at each of the orbits of the nine classical planets, you put an Earth. As you go further outward in the solar system, you cross a boundary where Earth is no longer able to clear its zone, because the zone is too big. It turns out that happens around the orbit of Neptune, maybe Uranus. So you would have nine identical objects, six of which you would call a planet and three of which you would not. They're identical in every respect except where they are.( http://www.space.com/12710-pluto-defender-alan-stern-dwarf-planet-interview.html)
I see your point that the resolution's footnote implies clearing isn't absolute and therefore Alan's lampooning (where he criticizes the lack of a specific metric by saying its absence implies absolute clearing) can be criticized for that reason. But putting this in Wikipedia would still be synthesis because there are no sources that go through that argument as you have done here. I don't see any sources saying, "The IAU's definition as-worded is adequate because the footnote clears up the vagueness." If there were, then that could be placed against Alan's argument as a disagreement. The IAU resolution is a citeable source about itself, but it is not a source for the derivative arguments. Presently I see several people (including yourself JeanLucMargot) saying to the press that the definition as-worded is not adequate, but I don't see anybody saying to the press or in published papers that Alan's particular way of criticizing its inadequacy is wrong.
Note that Mike Brown has also used lampooning when he criticized an alternative proposal, the one supported by the AAU's DPS. Mike says it would have included more than 53 bodies as planets, and thus it would have been a "no ice ball left behind" policy. This is not technically correct and could have been criticized since the geophysical definition of a planet leaves the vast majority of ice balls behind, those that aren't in hydrostatic equilibrium. The point of lampooning is not to be technically perfect, but to bring some inadequacy into sharp focus so people can grasp it, perhaps using hyperbole as Mike did. Attacking Mike Brown's "no ice ball left behind" statement on grounds that it technically misrepresented the DPS proposal would miss the point. Similarly, attacking this one of Alan's arguments that it isn't technically correct or complete for whatever reason is missing the point. The point is that the IAU definition fails to provide a measurable criterion, something everybody agrees with. Sanddune777 ( talk) 15:42, 4 April 2016 (UTC)
I asked Alan to respond to the criticism that he contradicted himself and I just got his response. Here is my question to him.
When you point out that not even Earth or Neptune have cleared their orbits, does that mean you no longer believe it’s possible to define orbit clearing in a precise way as you did in 2001? Or are you simply pointing out that the IAU definition failed to be specific?
Here is his response:
Fair question. About the point below, I am saying as I have long said, that the IAU’s statement on orbit clearing was sloppy. It speaks to cleared zones, not the ability to clear zones, and as we know, no planet’s orbit in this solar system is cleared (else there would be no NEAs, no trojans of Mars or the giant planets, no Plutinos in MMRs that cross Neptune’s orbit, etc.), this is in part because there are stable niches (1:1 librators as one example) and because there are always new sources of objects injected once a zone clears. The point of this particular criticism is to highlight the rushed and sloppy nature of the IAU definition, adopted in violation of its own rules, in the rush to get out of Prague. Science should not be sloppy, and scientists should not respect definitions with such clearly sloppy, flawed language.
This does not contradict his 2001 paper, and it does not imply that orbit clearing must be impeccable to be part of a dynamical definition. He is just criticizing the sloppy language that resulted from a rushed and flawed process. Obviously he knows we can define dwarf planets. Sanddune777 ( talk) 18:27, 4 April 2016 (UTC)
In the Margot's Π section it is stated: "Using Solar masses for the unit of mass for the star, Earth masses for the unit of mass for the planet-candidate, and AU for the unit of distance for the semi-major axis, k = 833." For Earth, these are all 1, so the formula for Π given reduces to Π=k and therefore Π should be 833 for Earth. However, in the table, taken from Margot's paper, the value for Earth is given as 810. Thus suggests the figure for k given in the article is incorrect. Comments? Cuddlyopedia ( talk) 08:04, 30 January 2016 (UTC)
Glad I wasn't seeing things! Great work on the table by the way. :) Whilst writing: In the table, I notice that for all the planets Λ>Π whereas for all the dwarf planets Λ<Π. Does this always hold, or at least when either/both value is not close to 1? If so, might be worth noting that unless the object is near the boundary it's only necessary to work out one of these, as the other follows. Cuddlyopedia ( talk) 13:41, 31 January 2016 (UTC)
While I am not arrogant enough to change the spelling to the American form (which appears several times both in the article and on this talk page), is there some historical basis for including the superfluous British 'u' in the title? Is that naming (and other) history worth mentioning in the article?
I wonder how the IAU defined the "neighbourhood" or "region" of a planet. Is it half an astronomical unit within the planet's center? Or 10.000 miles? 100.000 miles? 100.000 nautical miles? Since the IAU didn't concretize that the definition of "clearing the neighbourhood" is too vague to be taken seriously. And if Pluto and Eris were no planets according to that definition, so wouldn't be Earth, Mars or Jupiter. Complete nonsense which has nothing to do with whether a body is a planet or not. 212.186.7.232 ( talk) 09:18, 31 March 2019 (UTC)