Talk:Clearing the neighbourhood

message: 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)
thread_title: Programmatic Issue

message: 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)
replies: text: Yes, the Stern/Levison paper from 2002 used four slightly different versions of the phrase.  All four were quoted in an earlier version of this article.  Perhaps they should be put back in.  See /Archive 1#Origin of the phrase, and what to do about Stern, above.  64.122.41.167 05:58, 17 October 2006 (UTC)
thread_title: Stern's use of "clearing the neighbourhood"

message: 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)
thread_title:  graffiti 

message: 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)
replies: text: I'm taking out the confusing and expert tags, in that case. As for generalizing, I'm still not sure what can be done about that. The subject isn't a general one. Bryan Derksen 17:40, 28 April 2007 (UTC)
replies: text: Probably not clear from the first few sentences of the intro what it was about; I have rewritten. I hope you also don't mind that I've renamed this to cleared the neighbourhood - this is the far more common term, it's what the definition refers to; the process of "clearing the neighbourhood" is not really given much discussion in the article anyway. —The preceding unsigned comment was added by Abu-Fool Danyal ibn Amir al-Makhiri (talk • contribs) 16:44, 16 May 2007 (UTC)
thread_title:  What are the cleanup tags actually asking for? 

message: 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)
replies: text: But the only point of the parameter Λ for the casual reader (who only knows about Λ from this article) is the Λ > 1 vs. Λ < 1 distinction - the frame of reference is "cleared the orbit or not". Unless I'm mistaken, that's the whole point of the Λ parameter. This is an arbitrary parameter created for that purpose, and isn't something like mass or orbital period where the reader has at least a vague sense of Earth's value. If someone really wants to know what the values are compared to Earth, we'll still have the Earth value in the table. -- 76.204.102.226 (talk) 15:23, 24 August 2008 (UTC)
replies: text: I agree, so I added in a column for Λ. I also added a column for where Λ=1 for that body, saying how far out it could be to be a planet, since some have claimed that Mercury wouldn't be a planet if it was in Pluto's orbit. I used k=0.0043, with units in Yg and AU. Tbayboy (talk) 17:07, 21 February 2009 (UTC)
replies: text: What values are you using for the materials within the orbits? Jupiter would not dominate its orbit if it was surrounded by Jupiter-sized objects. Serendipodous 19:53, 21 February 2009 (UTC)
replies: text: Λ doesn't depend on the co-orbital materials, only the semi-major axis (or the period), the mass, and the approximately constant K (taken from the paper). One of Stern-Levison's goals with Λ was that it could be used outside the solar system, without needing to know unknowable (for the foreseeable future) data, i.e., small bodies. Soter's planetary discriminant is the one that needs the material estimate. Λ is a theoretical value indicating whether a body will clear it's orbit of small bodies, and μ is an observational value of how much a body has already cleared its orbit. Λ=1 is just kinda cool since it shows that Mercury would eventually clear out the Kuiper belt (if it was in, say, Quaoar's orbit), and that Pluto wouldn't clear out the main asteroid belt (if it was in Ceres' orbit). It's all just plugging the numbers into the equation shown on the page. Tbayboy (talk) 23:58, 21 February 2009 (UTC)

text: There's not much more to it than what is stated in this article, other than a bunch of math. They wrote an equation to figure out the probability of clearing a particular small body of given orbital parameters, then applied it to the numbers they had for the main belt objects to get the K. Is that value applicable to the trans-Neptunian domain? For Wiki purposes, have you seen many other papers refer to and use this parameter? Tbayboy (talk) 04:03, 2 October 2013 (UTC)
replies: text:  Well, there is an article on Mass–energy_equivalence, so one equation can have an article. What are the parameters, conceptually how do they lead to the probability, and so forth? For me, the ‘conceptually’ is the most important. I’m imagining a ten-minute lecture to keen undergraduates. JDAWiseman (talk) 17:27, 23 November 2013 (UTC)

text:  Request added to Requested_articles/Natural_sciences#Astronomy JDAWiseman (talk) 14:08, 26 November 2013 (UTC)
thread_title: Use of Λ<sub>E</sub>

message: 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)
replies: text: Well, now when you pinpoint it: true. Who (or what) clears which neighborhood? It's not possible to guess from the title what topic is treated. Maybe "Clearing the neighbourhood (planet dynamics)"? ... said: Rursus (bork²) 09:53, 12 March 2009 (UTC)
replies: text: I agree that the current  title of this article ("Clearing the neighbourhood") is awkward. A decent encyclopedia deserves more fitting titles for its articles. In the article I added the definition that "clearing the neigbourhood" is a "criterion" (adopted by IAU). An article named The criterion of "clearing the neigborhood"' may be too long, or is it OK? Any better suggestions? Or how about moving it as a section of IAU definition of planet? --HYC (talk) 22:13, 23 October 2009 (UTC)
replies: text: That article is quite long already. It's a phrase, and the most common one at that (or perhaps "cleared the neighbourhood", since we aren't really talking about the process but the fact of having done so). It's not obvious from the title who feeds what multitude either, but specifiers are for when there are other notable uses of the phrase. --99.245.206.188 (talk) 23:22, 20 February 2010 (UTC)
thread_title: Naming

message: Okay, this article has now been around a while.  Re this part:
:where k is approximately constant
...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)
replies: text: Don't expect the IAU to be self consistent. It's constantly contradicting itself. Every time they gather to meet, Zombie Feynman heads the other way in search of brains. 24.254.163.150 (talk) 17:40, 14 June 2008 (UTC)
replies: text: Oh, also, the reasoni t's "approximately constant" without an actual definition is so that they can adjust the value if need be to keep Pluto on the non-planet side of the line. Really, none of this had any kind of scientific motivation behind it, just arbitrary prejudice. I ridicule them for being rediculous. Did you know that their definition passed resolution with a 4% vote? That's not 4% more, that's 4% of the society voted to pass the resolution. The rest went home in disgust before the vote happened. 24.254.163.150 (talk) 17:58, 14 June 2008 (UTC)
replies: text: ROTFL! Shouldn't we consider deleting this Hype-advertizing article? It's probably just designed to inflate the egos of the planetary dynamicists - kind of blatant self-advertizing, maybe? Said: Rursus ☻ 20:28, 28 July 2008 (UTC)
replies: text: Well, since Alan Stern is one of those being "hyped", I can't say that only the dynamicists egos are being massaged here. Serendipodous 13:19, 12 March 2009 (UTC)
thread_title: K?

message: 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)
thread_title:  Suggest adding information in table for [[Makemake (dwarf planet)]] 

message: 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)
replies: text: Wow. Thanks. Missed that one. Serendipodous 18:38, 23 September 2008 (UTC)
thread_title:  Need to add Haumea 

message: According to the table, Lambda_Eris < Lambda_Pluto,  but Lambda_Eris/Lambda_E > Lambda_Pluto/Lambda_E
:It looks like the Eris/Earth ratio here is wrong. According to Soter's paper (the reference for that column), it should be 1.33e-8 (.002 / 1.5e5, versus the 1.41e-8 you would get from using the numbers in the lambda column, since Soter probably used slightly different Eris mass/AU numbers as his paper was published in 2006). Note that Soter didn't publish the ratio, so it looks like whoever calculated it here twitched a finger. Either sets of numbers (lambda columns or Soter's with lambda_Pluto = .003) will give reasonably similar results with the Pluto ratio being greater than the Eris ratio. Tbayboy (talk) 23:28, 8 June 2009 (UTC)
replies: text: Since whoever made the Lambda/Lambda_Earth column hasn't appeared, I fixed the entry using Soter's numbers. Tbayboy (talk) 21:09, 21 June 2009 (UTC)
thread_title:  Either Eris or Pluto is wrong in the table 

message: 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)
replies: text: Where do you see the word "cheese"? --Ckatzchatspy 04:52, 12 May 2011 (UTC)
replies: text: The problem was vandalism to Template:Esp, per this diff, but it's been fixed now. I should have thought to check the templates! - BilCat (talk) 09:00, 12 May 2011 (UTC)
thread_title: Speaking of food

message: 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)
replies: text: Not just the mass of the crossers (and grazers), but all objects sharing its orbital zone. --JorisvS (talk) 14:02, 8 October 2012 (UTC)
replies: text: Orbital zone IS the crossers (as explained in the article). The 0.33 is taken from the paper, so we can't do anything about it here. I think Ambi Valent's concern is valid in principle, but doesn't really have any practical effect: Vesta, Pallas, and Ceres all mutually cross, and each alone is enough to disqualify any other (the threshold is 100). Similarly, in the trans-Neptunian belt, Eris and Pluto range far enough to disqualify each other and everything else short of Neptune. The true value of any particular discriminant won't be exactly Soter's values, but, since they all fall short by orders of magnitude, a ballpark estimate is good enough. Tbayboy (talk) 17:24, 8 October 2012 (UTC)
replies: text: Not exactly, think of just-not-grazing minor planets. Planets would clear those too. In fact, crossing per se does not do it. Consider, for example, two Jupiter-mass exoplanets in exchange orbits or in moderately eccentric crossing orbits stabilized by a 2:1 resonance. Logically, this would then also apply to Neptune and Pluto (this still means Pluto is a dwarf planet, but for a somewhat different reason: the Kuiper belt). --JorisvS (talk) 17:56, 8 October 2012 (UTC)
replies: text: Just to be clear, the paper defines the orbital zone as if they share a common radial distance at some point in their orbits. I.e., the perihelion of the outer object is within the aphelion of the inner. Soter also excludes resonant objects and "comets". (I was interpretting Ambi Valent's "cross" to mean that, but I think you're interpretting it to mean one object crossing another's semi-major axis, and "grazing" as overlapping but not crossing the semi-major axis. I like your definition better.) Tbayboy (talk) 19:37, 8 October 2012 (UTC)
replies: text: I had meant "Ceres-crossers" as objects with a perihel distance smaller than Ceres' aphel distance and an aphel distance greater than Ceres' perihel distance. Anyway, I prefer the Stern-Levison parameter Λ when it comes to determine which object is a full planet and which isn't.Ambi Valent (talk) 21:47, 10 October 2012 (UTC)

text:  The real objection to the new planet definition is that it takes into account not only the mass or physical size of the planetary body...but its location (i.e. orbit).  This doesn't matter (too much) for very massive bodies, but for objects at the very boundary of the definition it matters a lot.   Look at the table in the article -- if Pluto is moved from the Kuiper Belt to the orbit of Venus (0.8 AU or less), its "clearing the orbit" ratio becomes greater than 1.00 and it qualifies as a planet.  For Eris, the qualifying orbit is roughly 1 AU (Earth's orbit).  Many astronomers are uneasy with a definition that depends on *where* the object is in the Solar System...because that makes the definition look like it was finessed to include just the eight most massive bodies (and to exclude the next 10 or so qualifying bodies).  It has the appearance of being scientific...without being so at all.  Imagine if a college had a qualifying formula that took into account your GPA *and* how many miles away you were from the university (i.e. a particular score would get you in *if* you were 300 miles away, but not if you were 1,500 miles away, etc.).  It would be clear that the formula discriminates against those with borderline GPA scores.  The union could have achieved its goal with a simple definition that said "are you rounded by gravity?  are you in orbit around the sun -- and only the sun?  are you 1,000 miles in diameter (or more)?   If yes-yes-yes you are a planet.  That would put Pluto and Eris in the group (and probably 10 more Kuiper Belt objects) and keep all the lesser stuff out.  But they didn't want to do that.  Thus, a Mars-sized body at 150 AU is not a planet...but at 90 AU it is a planet...which is nonsensical.  The article needs more content on the opposition to the formula  66.19.84.4 (talk) 00:50, 24 August 2013 (UTC)
replies: text:  That's a real concern.  I remember some comments around the time of the definition debate, which said that there are two main bodies of opinion - that of people such as plantary geologists, who consider the body in isolation, and are therefore interested in whether it is in hydrostatic equalibrium etc; and that of people who are interested in solar system dynamics, and are therefore interested in interaction between different bodies.  In my view, the IAU was quite wise in realising that the planet/not-planet boundaries are significantly different, depending on the type of science under consideration, and that we therefore need a 3-way classification.  Planetary scientists would therefore be interested in the boundary between (planet + dwarf planet) and (other objects), while solar-system scientists would be interested in the boundary between (planet) and (dwarf planet + other objects). Bluap (talk) 02:25, 24 August 2013 (UTC)
replies: text: It's not really a concern. There was (and is) little call (although non-zero) for making Mimas and Ganymede planets. If Earth was where Ganymede is, it wouldn't be a planet. Location matters. As Mike Brown pointed out, cleave nature at the joints. There's no joint between round and non-round, but there's a huge one in orbital dominance. Tbayboy (talk) 04:57, 24 August 2013 (UTC)

text: Yes, satellites, even those that are the size of (small) planets, are seldom considered "planets". This means that location clearly does matter! --JorisvS (talk) 14:34, 1 September 2013 (UTC)

text: Where have you seen opposition to the formula? Or even mention of it? There is some opposition to the concept of using clearing as the discriminant, but I haven't heard of any complaints of either of these specific formulae. Tbayboy (talk) 05:04, 24 August 2013 (UTC)

text:  I agree with editor "chesspride" on the Mars-sized body aspect of this.  The obvious flaw in the new planetary definition from the start has been that we can't be certain how objects got to be where they are.  (Did they form as planets within the solar system...or as something else or somewhere else?)  Essentially the current "clearing" definition serves as a mass cut-off for non-satellites.  As Stern has noted, this was done in reverse order to obtain a given a lower object count.  This contrived cut-off works at the moment because of the ~20 fold difference in mass between the largest known dwarf planets and the smallest inner planets.  However, who is to say that a relatively large (e.g. half the mass of Mercury or greater) but distant object won't be discovered?  The object will easily fail this "clearing" criteria.  For this and other reasons, the definition doesn't seem scientific...particularly when it states that "dwarf planets are not planets."  That's like saying short humans are not humans.  (The IAU shouldn't have called them "dwarf planets" if they weren't planets at all...something about subsets that I learned way back in early elementary school.)  Good luck with rationalizing the IAU's present definition, it falls short--yes, pun intended. Red Harvest (talk) 07:25, 4 April 2014 (UTC)
replies: text: It is a common fallacy to require a mass or size criterion for planethood. Clearing the neighborhood is about dominance, not about size. Dwarf planets are usually smaller than planets, but need not be. It is quite scientific; in fact, a criterion based on size or mass will need an arbitrary (i.e. non-scientific) cutoff to lead to 8 (or 10) (known) planets. You could call dwarf planets 'planets', but that makes no difference: the major real-world difference between the dominant 8 and the other round bodies remains. --JorisvS (talk) 11:42, 4 April 2014 (UTC)
replies: text: That is a strawman argument as I didn't set the criteria, I'm observing it's effect.  It is largely about size, because the combination of mass and location is what sets "dominance."  But if you put any of the inner planets far enough out they are also no longer planets.  Furthermore, the current 3rd criteria was attained in a non-scientific manner:  to specifically exclude bodies, while at the same time still calling them planets with only a qualifier in front.  Creating a rigged test to get a specific result doesn't exactly inspire trust or confidence in the methodology.  I don't have a problem with the dwarf planet nomenclature for Pluto, Ceres, Eris, etc., but I do have a problem with the IAU claiming something they've named a planet is not a type of planet.  That's such obviously twisted logic that even elementary school kids start guffawing about it.   And why is that the IAU decided to create such a hilarious contradiction?  It appears that they were unwilling to take the next logical step at the obvious break point between the giant outer planets and the much less massive inner planets and create more defined subsets of planets.  (For illustration compare the mass ratio of Neptune and Earth: 17:1 with that of Mercury and Pluto: 25:1 or Mercury and Eris: 20:1.)  Stern does a very good job of breaking all of this down in the following article:  http://www.space.com/9594-fighting-pluto-planet-title-planetary-scientist-alan-stern.html  Dwarf planets are still merely a subset of planets, just as dwarf stars are still a subset of stars whether or not said stars have "dominance." Red Harvest (talk) 08:37, 5 April 2014 (UTC)
replies: text: It is quite common for an X Y not to be Y (i.e. a dwarf planet is not a kind of planet, nor is a minor planet; a sea lion is not a lion). --JorisvS (talk) 18:21, 5 April 2014 (UTC)

text: Orbital dominance was already something Alan Stern himself noted. He only gave different terms to the same categories as those formalized in the IAU definition; the awkward semi-German "überplanet" and "unterplanet" for the IAU's "planet" and "dwarf planet"; the only upside was that in his terminology there is a term for planet+dwarf planet ("planet"). In spite of different terminologies, the concepts are identical. --JorisvS (talk) 18:27, 5 April 2014 (UTC)

text: Where did Stern say that dominance was used to achieve the pre-determined number? I find that hard to believe, since it was Stern himself who made the division (uber/unterplanet) well before the IAU addressed the issue (and even then, the IAU started with roundness, not dominance!). The dominance gap is not just an idiosyncracy of our system but a consequence of the physics. As for "dwarf planet", there were few complaints about "minor planet" for well over a century. Similarly, for roundness, there were no petitions to reinstate Ceres to planethood. The previous silence on these issues shows that these objections to the IAU definition aren't about science, but the emotion of Pluto. Tbayboy (talk) 13:34, 4 April 2014 (UTC)
replies: text: I'll add that it is, of course, no coincidence that the planets are all much bigger than the known dwarf planets. The more massive an object, the more easily it can scattered other objects or sweep them up, and the more easily it clears its orbit. Stern talks about "dynamically important" objects or objects that "dynamically control" their surroundings. I'd say that's clearly the same thing as 'dominance'. --JorisvS (talk) 15:15, 4 April 2014 (UTC)
thread_title:  Ceres planetary discriminant 

message: 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)
replies: text: It's not garbage: it shows the development of the concepts leading to "dwarf planet". Tbayboy (talk) 17:58, 15 December 2013 (UTC)
thread_title:  überplanet 

message: 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)
replies: text: True, the relative masses do not matter. It has cleared Pluto from its orbit. Specifically, it has put Pluto into a resonant orbit so that Pluto never comes close to it. That Neptune does this shows it gravitationally dominates its orbit. As for Earth, though, NEAs are continually cleared and replenished; that the dominant body is Earth can be seen from the relative masses, but this is not the reason for the dominance. --JorisvS (talk) 15:24, 5 October 2014 (UTC)
thread_title:  Planetary scientist's understanding. 

message: 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)
replies: text: Simple: As seen from a co-moving reference frame. And dark matter and dark energy do not have a measurable effect within the Solar System. --JorisvS (talk) 19:02, 7 November 2014 (UTC)
thread_title:  Problem 

message: 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)
replies: text: Actually, resonant orbits, such as that of the trojans (1:1) with mostly Jupiter or Neptune, are a special case of clearing the orbit. They have been put in a very specific configuration that is only possible with a dominant object, i.e. a planet. Similarly, Neptune has the plutinos, with Pluto the most prominent example, in resonant (2:3) configuration, which can cross Neptune's orbit. Again, this is a special case of clearing the neighborhood. And even if it weren't, like in the case of the near-Earth objects, for example, the combined mass of the objects is so small that nearly all of the mass is still in the planet whose orbit they cross (see the μ in the table). --JorisvS (talk) 15:41, 15 July 2015 (UTC)
thread_title:  Trojans / L4, L5. 

message: 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)
replies: text: I have been considering it, too, but I'm a bit fuzzy on how he calculates the scattering. I was hoping to find some of his sources for that, but I haven't had time recently. Π seems cleaner than Λ, since it seems based on the physics of the situation rather than the statistics of a particular set of bodies (Λ's "approximately constant" k). His acknowledgements section mentions conversations with Levison, Soter, Lineweaver, and others, so it seems a good candidate for "best to date" characterisation of clearing. As you allude, it's not a fixed formula, but a template formula that can be parameterised by the size of the orbital zone to clear and the speed of clearance. Tbayboy (talk) 05:09, 1 December 2015 (UTC)
replies: text: In the paper he was using a template formula with different parameters, but in the proposal he published in the Astronomical Journal, he used the values that return the loosest requirement and rounded the result. See here: http://mel.epss.ucla.edu/jlm/  Ambi Valent (talk) 00:21, 2 December 2015 (UTC)
thread_title:  Add Jean-Luc Margot's planet discriminant? 

message: I think Planet Nine should be added.
: In case it's helpful, I uploaded a figure showing that Planet Nine would clear its orbit https://commons.wikimedia.org/wiki/File:Margot2015OrbitClearingCriterionWithPlanetNine.png JeanLucMargot (talk) 22:01, 23 January 2016 (UTC)
replies: text: Not here, until it's actually discovered. Should be okay in the Planet Nine page. The expected eccentricity is a problem here, too. Maybe P9 will spur work on that front (nudge nudge wink wink). Tbayboy (talk) 06:23, 24 January 2016 (UTC)
thread_title:  Need to add Planet Nine. 

message: 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?
:It's how the IAU spells it in the source for the term. It's a common and valid spelling, so it's not worth mentioning. That's not meant as an argument against changing it, just an explanation. Tbayboy (talk) 17:31, 10 February 2017 (UTC)
thread_title:  Spelling? 

message: 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)
replies: text: See Hill sphere. Ruslik_Zero 07:03, 1 April 2019 (UTC)
replies: text: Then the third point should've been called "clearing the Hill sphere". Still, some of the eight other planets wouldn't be planets according to that definition. The nonsense with this is also that a planet that hasn't cleared whatever is considered a "dwarf planet" which presumptively assumes that the body is very small but that's not the case with Jupiter for example (a giant planet that would have to count as dwarf planet according to the IAU). But the IAU's definition is anyway wrong because planets don't have to orbit a star. A planet is any celestial body in hydrostatic equilibrium that's neither a star (including L- and T-type stars) nor a moon. 212.186.7.232 (talk) 05:52, 2 April 2019 (UTC)
thread_title:  Totally vague