Talk:Figure of the Earth

message: Since figure of the earth is an expression, shouldn't the name if this article be Figure of the earth? Kingturtle 03:12, 13 Dec 2003 (UTC)
replies: text: I don't understand the title. Why isn't it called "Shape and size of the Earth"? This would be a more normal English expression. Borock (talk) 13:21, 1 December 2009 (UTC)
replies: text: We must use the term most often used in the references, which is "figure of the Earth". This figure is indeed its shape and size. — Joe Kress (talk) 19:32, 1 December 2009 (UTC)
replies: text: Cool. You learn something every day. Which is one reason to visit WP. :-) Borock (talk) 05:07, 15 December 2009 (UTC)
thread_title:  article name 

message: * Figure of the Earth - This has been lifted from a public domain web page .  No problem there, but it refers to a number of non-existent diagrams.  These could probably be borrowed from the same source, but they are of poor quality. --Heron 17:01, 27 Nov 2004 (UTC)
thread_title:  from PNA/Geology 

message: The article describes many ways of approximating the shape of the earth, but other than the triaxial bit or the pear shape thing, the article doesn't mention what the figure of the earth is to any appreciable degree. Where are the relative high and low points of the geoid. —Preceding unsigned comment added by 71.102.144.27 (talk • contribs) 03:00, 14 March 2007
According to NASA (http://www.nasa.gov/worldbook/earth_worldbook.html) the earth is pear-shaped. ig 12.110.164.222 (talk) 21:49, 10 December 2010 (UTC)
thread_title:  The ''actual'' figure of the earth 

message: "The angle between the plumb line  which is perpendicular to the geoid (sometimes called "the vertical") and the perpendicular to the ellipsoid (sometimes called "the ellipsoidal normal") is defined as the deflection of the vertical."  
But what is the sign convention?  I believe the deflection is the angle from the vertical to the ellipsoid normal.  Right?  Jrvz (talk) 20:41, 19 October 2010 (UTC)
replies: text: The reference direction is usually the ellipsoidal normal, hence from the ellipsoidal normal to the plumb line. In addition, the deflection of the vertical relative to the ellipsoidal normal has a north-south component ξ and an east-west component η, where north and east are positive. See Geodesy pages 218–219. — Joe Kress (talk) 08:35, 20 October 2010 (UTC)
thread_title:  Deflection of the vertical 

message: Who knew; the Earth really is flat!JoelDick (talk) 13:22, 26 May 2014 (UTC)
thread_title:  Flat Earth 

message: The Image of an Oblate Spheroid on this page is a gross exaggeration of the oblateness of Earth. Its a bad example, misleading and confusing and it should be removed from this page.  — Preceding unsigned comment added by Steveengelhardt (talk • contribs) 16:15, 24 September 2016 (UTC)
thread_title:  Remove Oblate Spheroid 

message: User:Bobbie73, please restore this article to its name Figure of the Earth, which is a term of art. Figure of Earth is not idiomatic; nor does it appear in the technical literature. The article's name is now broken and does not mean what the article was written about. Thanks, by the way, for your other edits in related articles. Strebe (talk) 17:50, 3 June 2017 (UTC)
replies: text: Since User:Bobbie73 has not reversed the inappropriate move, I have done so. Jc3s5h (talk) 12:33, 4 June 2017 (UTC)
thread_title: Restore article name

message: Neil Degrasse Tyson is some sort of US TV chap. Apparently he's described the Earth as a "pear-shaped oblate spheroid".  Is there a source for this? Is it accurate?  I understand why the Earth would be oblate, but why "pear-shaped"?  What's the mechanism for that? Andy Dingley (talk) 23:24, 20 July 2017 (UTC)
replies: text: This is explained in this very article in “More complicated shapes”. Strebe (talk) 00:35, 21 July 2017 (UTC)
replies: text:  I've just added more sources to Figure_of_the_Earth#Pear_shape. fgnievinski (talk) 17:18, 27 August 2019 (UTC)
thread_title:  Pear? 

message: User:GliderMaven has twice copied a pile of material from the Flat earth article. This material has several problems.
*The term figure of the earth is a geodetic term. It does not, and never has, referred to a flat earth model.
*At the top of the page, the article already states, For the historical development of the concept, see Spherical Earth and Flat Earth, in order to distinguish cognitive models from the topic of this article.
*We do not copy sections between articles. The Flat earth article exists to talk about the history of the flat earth model. This copy/paste adds nothing to the topic and risks getting out of sync with the material it was copied from.
*The article already mentioned that small parcels can be treated as flat; it does not need a digression into archaic conceptions of a flat earth.
*Although flat earth models are often used for small areas a far more accurate model for the shape of the entire Earth is clunky English and misleading in content. There is no relationship between "flat earth models" and ignoring earth's curvature for purposes in which the curvature is irrelevant. They're two entirely different concepts.
I have reverted this edit again and will challenge its inclusion if attempted again. Strebe (talk) 18:06, 11 September 2017 (UTC)
replies: text: You have not addressed any of my points. And no, mappa mundi are not maps founded on a flat earth model. Pre-scientific societies have nothing to do with the geodetic term of art "figure of the earth". These concepts are addressed in other articles as noted at the top of the page already. The fact of "two paragraphs" is not relevant. Strebe (talk) 18:27, 11 September 2017 (UTC)

text: The geometry of mappae mundi and their flat/spherical basis is a topic of modern dispute. Speaking for myself, I see the earlier T-O form, where the border is oceanic rather than antipodean, as still fundamentally flat. They're not some Aristotelian hemispherical earth, nor are they Crates' divided uncrossable sphere. Andy Dingley (talk) 21:16, 11 September 2017 (UTC)
replies: text: It is not our place to debate the cosmography of mappa mundi; claims of ambiguity only disqualify their relevance here, not enhance it. Despite the sphere’s simplicity, it is •still used• as a model, and reasonably so: not because we mistakenly believe the earth to be a sphere, but because the sphere is a useful model for the entire earth. A plane is not a useful model for the entire earth and is not included in the geodetic term of art “figure of the earth”. This article is not about the history and development of humanity’s conception of the earth’s shape. The plane isn’t even a unique precursor to the spherical model, so injecting it into the article as if it were special and as if the models represent some historical, logical progression, would be wrong. Strebe (talk) 01:07, 12 September 2017 (UTC)
thread_title:  Flat earth material 

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thread_title:  External links modified (January 2018) 

message: This subsection: Figure_of_the_Earth#More_complicated_shapes
I have one question: is it still a matter of controversy? When was the controversy settled if not at all? I'm certain that the Earth's shape is well documented.
--Foia req (talk) 02:52, 7 October 2018 (UTC)
thread_title:  More complicated shapes subsection 

message: There is a move discussion in progress on Talk:Earth's circumference which affects this page. Please participate on that page and not in this talk page section. Thank you.  —RMCD bot 23:03, 6 January 2019 (UTC)
thread_title:  Move discussion in progress 

message: The cited reference apparently says Columbus speculated the Earth was pear shaped, it is not possible for him to have known this. The Earth is indeed pear-shaped (discovered by exquisitely precise satellite observations), but at a level of one part in a MILLION, tens of meters at distances and lengths of millions of meters. Columbus was on a heaving ship with plumb-bob on the end of a string, thousands of kilometers from the place where it deviates from a sphere. The cited reference information flies in the face of physics, the history of science, mathematics and logic; authors have been know to be wrong. Columbus could not have measured this ppm effect in his time with his equipment and his situation, if he claimed to, he was guessing/just-wrong/misunderstood.  How would he even measure it, he was millions of meters from the point of deviation?  His speculation was just that, unsubstantiated speculation, just random noise that meaning can be read into, like the predictions of Nostradamus. This does not belong in Wikipedia.  — Preceding unsigned comment added by Dr.gregory.retzlaff (talk • contribs) 22:00, 25 February 2022 (UTC)
replies: text: if he claimed to, he was guessing/just-wrong/misunderstood.  How would he even measure it, he was millions of meters from the point of deviation?  His speculation was just that, unsubstantiated speculation, just random noise that meaning can be read into, like the predictions of Nostradamus. That part is true. This does not belong in Wikipedia. That part is false. Columbus is robustly documented to have speculated that the earth was pear-shaped, even if his his methods were inaccurate and his beliefs superstitious. The article shouldn’t give the impression that Columbus’s belief was competent, but it is wrong not to note the first documentation of the belief. Strebe (talk) 23:07, 25 February 2022 (UTC)

text: The insignificance of the deviation is a technicality which could use more focus in the article. How many meters of variation  from a perfect sphere does this imply, for instance? Then the reader will be able to see/interpret for themselves how impossible it was for Columbus to actually observe. UpdateNerd (talk) 23:46, 25 February 2022 (UTC)

text: The current text, Making observations with a quadrant, he "regularly saw the plumb line fall to the same point," instead of moving respectively to his ship, and subsequently hypothesized (ludicrously) that the planet is pear-shaped, is nothing I can document. If it appears in the cited work, it’s the author’s invention, as far as I can tell. All the references I find have Columbus speculating on religious/cosmological/confused grounds, not from measurements. A mention should remain, for the reasons given, but not this business about measurements. Strebe (talk) 01:49, 26 February 2022 (UTC)
replies: text: I wouldn't mind it being shortened somewhat, but I don't think it's the author's "invention". I believe other sources mention his use of a quadrant in the matter. Not every source discusses every last detail of his voyages. UpdateNerd (talk) 02:37, 26 February 2022 (UTC)
replies: text: The current text must go. It's meaningless gibberish, which gives no insight, not even a false insight, as to what Columbus was thinking. Jc3s5h (talk) 02:39, 26 February 2022 (UTC)
replies: text:  I think you're correct, the author put this into Columbus's mouth (as far as I can tell), rather than quoting his journals as I assumed. My bad. We should definitely ditch the quote. UpdateNerd (talk) 03:15, 26 February 2022 (UTC)

text: Well it avoided citing the inventive author and cleaned up a bunch of confusing word salad. If you think you can improve it, feel free to make the improvement. Why do you assume his model was "perpendicular"? UpdateNerd (talk) 22:01, 28 February 2022 (UTC)
replies: text: I don’t “assume”; I looked into it. He posited a pear shape because he couldn’t figure out where all these new lands he was finding fit into his conception of a spherical world. So, he decided that the new lands were a continent hanging off of China on a bulbous lobe, making the earth pear-shaped with the stem, if it were present pointing away from the equator. He rationalized this by saying that the earthly paradise is closer to the sky than the rest of the world, and that biblical sources say that the earthly paradise is in Asia. The modern understanding of the (extremely faint) pear shape is that the stem would rise from the north pole. Strebe (talk) 22:18, 28 February 2022 (UTC)
replies: text: I think that's very interesting, but it's difficult to make any sense of Columbus's model. He only said it pointed towards Heaven, and he's entirely inconsistent about whether he talking about Eden (which he already said was in South America, which he believed was Asia), or the celestial "heavens" above. The simplest interpretation is that it would be at one of two poles (since he based his model on the apparent difference of Polaris's diurnal motion). But there's too much ambiguity to assume anything. A primary source would be helpful, since authors clearly like to editorialize upon the subject. UpdateNerd (talk) 22:25, 28 February 2022 (UTC)

text: What kind of mess would Wikipedia be if it were based on people’s undocumented assertions? Because I know something about geodesy and something about 15th century instruments and something about Wikipedia, it was clear to me that Columbus didn’t credibly measure his way into a belief about a pear-shaped earth. So, when you called attention to the offending passage, it was obvious to me that (a) you were right about the measurement; and (b) you weren’t right that the mention needs to be deleted. Thank you for calling attention to the problem. We’ll get it fixed properly. Strebe (talk) 04:05, 1 March 2022 (UTC)
thread_title:  Columbus and the pear shaped earth