Talk:Tychonic system

message: I was puzzled by the references to the scientist as "Tycho" rather than "Brahe," so it seems worth noting the reason for this (according to the Tycho_Brahe page, anyway).  Supposedly this was the convention of the time in his native Scandia, and has become convention.
--Stellmach 01:14, 16 July 2006 (UTC)
thread_title: "Brahe"

message: The current following last para obviously a blunder on Bessell and Henderson who discovered stellar parallax in the 1830s, not stellar aberration in early 18th.
"The discovery of stellar aberration in the early 18th century by Bessel, Henderson and James Bradley established that the Earth did in fact move around the Sun, after which Tycho's system fell out of use among scientists. In the modern era, the few who still subscribe to geocentrism use a Tychonic system with elliptical orbits."
Will correct --Logicus (talk) 19:07, 10 January 2008 (UTC)
thread_title: Blunder on Bessell and Henderson

message: Based on the theory of a Tychonic system, the sun and moon orbit the earth, and the other planets in the solar system orbit the sun.  But what about stars (other than the sun)?  I assume that they orbit the earth in this theory, but the article should probably state that explicitly.  And what about the comets in the solar system?  Or moons of other planets in the solar system?  There's also the issue of planets in other planetary systems, but I suspect that they weren't known at the time. - Shaheenjim (talk) 07:39, 10 February 2009 (UTC)
replies: text: When Tycho published there were no other moons known in the solar system (not until Galileo's discovery of the moons of Jupiter in 1610). But those can be accounted for quite easily in this model (vs. the Ptolemaic) as the idea of multiple sources of rotation is accepted. As with the Ptolemaic system, the sphere of stars itself rotates around the Earth (I doubt the difference of them rotating around the sun would be detectable?). And "other planetary systems" were totally out of the question (they've barely really entered the question today!).  --98.217.14.211 (talk) 01:14, 11 March 2009 (UTC)

text: One of Brahe's primary objections to the Copernican model was the immense distance and size of the stars required.  He contended that the stars were much closer and of a comparable size to our Sun. JoshuaLibrarian (talk) 20:57, 11 April 2022 (UTC)
thread_title:  Stars 

message: This page says it is essentially equivalent to the Copernican system, which seems fair enough: you just have to shift your fixed point from the sun to the earth.
However, that clearly means that the Tychonic system uses epicycles (hence I removed "and eliminated all need for epicycles"). That also means the lede picture is flawed/simplifed, since it shows things going round in circles William M. Connolley (talk) 21:15, 21 October 2011 (UTC)
replies: text: I changed it to being equivalent to a heliocentric system, but you changed it back, saying that it was not equivalent to all heliocentric system. That's right, but I did not say that it was equivalent to "all" heliocentric system. Saying that it was equivalent to the Copernican system can be misleading because of the epicycle issue you noted. Roger (talk) 21:03, 22 October 2011 (UTC)
replies: text:  I'm trying to find a good source for this, but I think that the T system really is *exactly* equivalent to the C system, but shifted of course. It can, obviously, only be equivalent to one sun-centered system. I *think* T just took C's system (epicycles and all) and shifted the earth to the center. One of the other pages about geocentrism - but I can't find it now - asserts that the two systems are exactly equivalent William M. Connolley (talk) 21:10, 22 October 2011 (UTC)
replies: text:  So you changed a correct statement into a dubious one that you are unable to substantiate. I suggest that you change it back, and leave it that way until you find a source that backs up your claim. Roger (talk) 22:37, 22 October 2011 (UTC)
replies: text:  No. The correct statement is that it is Copernican (assuming it really is - I still don't have a good source for this, I admit.  is a source,  another, but may not be good). Your version is wrong - it must be. There are many heliocentric systems: Keplers, Copernicus's, ours. They cannot all be equivalent to the Tychonic system, obviously William M. Connolley (talk) 21:00, 23 October 2011 (UTC)
thread_title:  Epicycles 

message: Don't like this . Tycho died in 1601 William M. Connolley (talk) 08:15, 23 November 2011 (UTC)
thread_title:  This was, of course, alse 

message: Apparently this point may have been previously discussed.  Also, this is not my area of expertise.  Still, I am troubled by a statement in the article:  "It can be shown that the motions of the planets and the Sun relative to the Earth in the Tychonic system are equivalent to the motions in a heliocentric system."
Is this statement  completely accurate?  I do not think so.  Perhaps the term "heliocentric system" must be qualified in some way, e.g., so as to eliminate Keplerian elliptical orbits with varying orbital speeds.  Absent an infinite number of, e.g., epicycles, can a circular orbit constant velocity Tychonic system be rendered completely mathematically equivalent to an elliptical orbit variable velocity heliocentric system?  I do not think so.  Also, as noted in the previous discussion, at the very least the terms "Tychonic system" and "heliocentric system" need further specification.  Otherwise it is unclear what is even being asserted.
So, in short, the cited problematic statement needs more work.  — Wsjacobs (talk) 03:05, 18 August 2013 (UTC)
replies: text: Shirley the key point is the (mathemeatical, not physical) equivalence of the Tychoian and Heliocentric systems. It doesn't matter exactly *which* heliocentric system, you get an entire family of Tychoian ones, each corresponding to a heliocentric one. The pix we show here in the article clearly don't correspond to a Copernican one, since the Tychoian orbits are shown as circles, but Copernicus throws in epicycles and all that antique hangover crap William M. Connolley (talk) 07:19, 31 August 2013 (UTC)
replies: text:  Thank you for your post.  In order to clarify the matter further I re-edited the problematic sentence to read:  "It can be shown that the motions of the planets and the Sun relative to the Earth in Brahe's system are mathematically equivalent to the motions in Copernicus' heliocentric system."  In this way, both intended referents are adequately specified, as well as making explicit the asserted equivalence.Wsjacobs (talk) 00:51, 1 September 2013 (UTC)
thread_title:  Possible error in the relation of the Tychonic and heliocentric systems 

message: It is not possible for a Tychonic system to "fit" better than a Copernican system.  The two are clearly fully dual in that they are transformable to each other, with the except of the observation of the stars.  Longomontanus et al, (the Tychonics) may have fit a better system to Tycho's more accurate data (they were within a factor of 2 of Tycho's margin of observational error), but that just meant that there was corresponding heliocentric system that was just as well fit.
In support of Tycho's system it just be limited to saying that, unlike the Copernican system, it removed the parallax problem and retained a non-moving earth, which most people favored at the time (even at this time, this was already widely debated.)  One should not give the reader a false impression that Tycho's system was in any way better than the Copernican system, on data fitting or otherwise.
Remember, that in parallel to the Tychonic's work, Kepler was working on his own Copernican system and at pretty much the same time produced a system whose fit with Tycho's data was less or equal to the margin of error of his observations.  My only point of this being that Tycho's system would not have been correctly and widely considered "more accurate" since it was not.  So we should probably not say that in the article.  Removing the parallax and maintaining geocentrism were its primary and only trumps at this time.
Qed (talk) 23:22, 4 December 2014 (UTC)
thread_title:  Fit "better" than the Copernican system. 

message: The first picture in this article is 
 (the one shown here.) 
The caption [the one in the article -- (not here on the "Talk:" page)] for that first picture says:In this depiction of the Tychonic system, the objects on blue orbits (the moon and the sun) rotate around the earth. The objects on orange orbits (Mercury, Venus, Mars, Jupiter, and Saturn) rotate around the sun. Around all is a sphere of stars, which rotates.
IMHO that use of the verb [the word] "rotate" is incorrect (it should say "revolve" instead).  
I did check wikt:rotate, the Wiktionary entry ("s.v.") for the word "rotate", and wikt:revolve, the Wiktionary s.v. for the word "revolve".  
Yes, I am aware that it does say that "rotate" can mean "revolve", and "revolve" can mean "rotate".  However, IMHO that does not mean that using one to mean the other, is a good idea, or is advisable in an encyclopedia like this (where, IMHO, it is preferable [advisable] to use language carefully, and to set a good example for readers, of the correct [or, "the more correct"] way to use such verbs). 
Even though Wiktionary does say that "rotate" can mean "revolve", and "revolve" can mean "rotate", this can be explained by the fact that  Wiktionary (or any similar dictionary) sometimes backslides from being prescriptive) and instead lapses into a tendency to describe (or reflect) current usage.  (...along with the fact that, "current usage" might be full of mistakes made, by those who are ignorant of the "best practices" for using these verbs.) 
So, even if we like to be nice and kind and forgiving here, IMHO it is not advisable to completely forget about setting a good example!  I suggest that, -- (without offending anyone) -- this article[well, the caption of the first picture, in this article] could improve its use of the verbs "rotate" and/or "revolve".  
Notice:  The Wiktionary entry for the word "revolve", (see wikt:revolve#Verb) does show, as an example sentence -- the first example sentence! -- this sentence:The Earth revolves around the sun.while the Wiktionary entry for the word "rotate", (see wikt:rotate#Verb) shows, as its first example sentence -- this sentence:He rotated in his chair to face me.  
These examples can serve as a hint as to what the "best practices" are, here.  That is, [set a good example by doing this:] use "revolve" for sentences like "The Earth revolves around the sun.", and use "rotate" for sentences like "He rotated in his chair to face me.". 
I intend to edit that caption, in accordance with this philosophy.  The proposed edit would probably consist of: 
* changing "rotate" to "revolve" 3 places; and  
* adding "around the earth" at the end of the last sentence
If anyone has any objections (or advice, or other comments), then please [feel free to] chime in. 
If there are no responses -- after some reasonable time, to wait for comments, "if any" -- then I intend to go ahead with this edit. 
Sorry this was so long.  Thanks for listening. --Mike Schwartz (talk) 07:21, 19 February 2015 (UTC)
thread_title:  "Room for improvement" in the caption of the first picture  

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