Talk:Nutation

message: I just think it's hilarious that an explanatory article on nutation doesn't mention frisbees.  — Preceding unsigned comment added by 205.153.180.229 (talk) 16:43, 8 November 2011 (UTC)
thread_title:  Frisbee 

message: The precessing North pole of the earth should follow a clockwise path around the axis of the ecliptic when viewed from above the ecliptic, which is the opposite of what we see in the illustration that accompanies this article  —Preceding unsigned comment added by 188.118.69.232 (talk) 11:17, 24 October 2010 (UTC)
replies: text: You are, of course, correct.  However, the direction of precession is entirely correct for the direction of rotation of the hypothetical planet illustrated.  It is not an illustration of the earth looking at the north pole because the direction of rotation of the earth is anticlockwise (looking toward the north pole). 86.144.90.137 (talk) 12:32, 12 September 2012 (UTC)
replies: text:  Opposite? I think that just not all of celestial IPs look to the Earth from Polaris and Ursa Major constellation. Possibly, there are users on Proxima Centauri too – why their PoV should not be represented? Incnis Mrsi (talk) 14:10, 12 September 2012 (UTC)
replies: text: By convention, the north pole of a planet is the pole where the planet spins anticlockwise.  This is true even for Uranus which has a technically retrograde direction of spin in that its north pole is ~6 degrees below the orbital plane (relative to the remaining 7 planets).  Also by convention, the earth is generally depicted with the north pole at the top.  Even in Australia they don't sell up-side down globes! 86.144.90.137 (talk) 15:25, 12 September 2012 (UTC)
replies: text:  Remaining 7, you said? What about Venus? Incnis Mrsi (talk) 15:35, 12 September 2012 (UTC)

text:  You describe the right way to do it, but see Poles of astronomical bodies. —Tamfang (talk) 18:13, 12 September 2012 (UTC)
thread_title:  Wrong Orientation 

message: I am a bit concerned about the Nutation article. I wonder if a slight clarification might be added related to the difference between Nutation and Wobble/Polar motion.
The motion of the Earth's rotation axis on the celestial sphere is given by Precession, Nutation PLUS a smaller remainder called the "celestial pole offset". http://www.iers.org/MainDisp.csl?pid=95-93
It is very common to mix up "celestial pole offset" with the geographic motion of the pole on the surface of the earth, known as "Polar Motion" or "wobble". 
The IERS monitors both Polar Motion (GPS & VLBI) and the celestial pole offset (VLBI).
Imagine that polaris is exactly at the north celestial pole and we experience 1m of Polar Motion/Wobble. This would mean that: 
- My apparent latitude and longitude would change as I view the stars. Polaris would be at a slightly different position in the sky at a fixed location. 
- Polaris would remain at exactly at the north celestial pole. 
Now imagine that polaris is exactly at the north celestial pole and we experience a 1m offset of the celestial pole. This would mean that: 
- My apparent latitude and longitude would be unchange as I view the stars. The north rotation pole would be unchanged. 
- Polaris would no longer be exactly at the north celestial pole. 
132.156.28.88 (talk) 19:54, 6 August 2008 (UTC)
thread_title:  Nutation / Wobble/Polar motion 

message: This starts to be a real mess. I've tried to get a grip of what different kinds of polar motions we have all together, by doing research here on Wikipedia, and here's what I've got so far:
* True polar wander
* One of the Milankovitch cycles of about 40 000 years
* Several nutations of the Earth, the largest to have a period of about 18 years
* Polar motions, one of those the Chandler wobble with a period of 433 days
* Celestial pole offset, mentioned above
Could the differences between these concepts be clarified? And maybe a summarization of these different kinds of polar motion, could be written in the main article?
Mårten Berglund (talk) 23:37, 14 October 2008 (UTC)
thread_title:  Different kinds of polar motion 

message: What's the maximum angle of the Earth's nutation? The nutated axis is shifted how many arc seconds from its mean position? That info ought to be here somewhere.
Seems like it should be 10+ seconds-- but can that maximum occur at any time in the 18.6-year cycle? If it can, nutation in longitude would sometimes exceed 23 arc seconds-- which it never does? Tim Zukas (talk) 23:05, 5 August 2011 (UTC)
thread_title:  Maximum nutation (angle on celestial sphere)? 

message: I had to edit this article from the top, to add a new section ("Physiology"), and my computer displayed the following as word-salad:
ml:അക്ഷഭ്രംശം
Would someone with the proper character sets be so kind as to check the article's history and, if need be, replace these characters? Thanks! Jonah Winters (talk) 16:31, 12 October 2011 (UTC)
thread_title:  Did I mess up the Malayan characters? 

message: I just discovered that there is an article on Free nutation with nothing more than a dictionary definition. Seems pointless. I propose merging it with Nutation. If the material on free nutation grows enough, it could always be split off again. RockMagnetist (talk) 18:14, 9 August 2012 (UTC)
replies: text: Nothing to merge. First, a material object cannot be a sphere. It may be a ball, though (it is a very common confusion among English-speakers). Second, these are the inertia tensor, as well as mechanical properties, which do matter, not the form. Just redirect and forget. Incnis Mrsi (talk) 19:09, 9 August 2012 (UTC)
replies: text:  I agree with your proposed action. Globbet (talk) 23:28, 9 August 2012 (UTC)
replies: text: Same here. Maschen (talk) 10:28, 16 August 2012 (UTC)

text: Given the triviality of the merge - I just did it now. Maschen (talk) 10:36, 16 August 2012 (UTC)
replies: text: Thanks. Having allowed a week for responses, I had forgotten about it! RockMagnetist (talk) 16:18, 16 August 2012 (UTC)
replies: text: I reverted it; you created a redirect to an article that does not include the term. One of the most annoying things on Wikipedia from a reader's perspective, enter a search term, get redirected to an article that doesn't use that term. -68.107.137.178 (talk) 10:36, 8 May 2013 (UTC)
replies: text: Although I agree that it is annoying, please don't undo consensus changes without discussion. The proper solution is to mention free nutation in this article. Apparently the merge wasn't done correctly. RockMagnetist (talk) 16:35, 8 May 2013 (UTC)

text: I have added the definition of free nutation to the lead. RockMagnetist (talk) 16:40, 8 May 2013 (UTC)
replies: text: Actually, the consensus was to delete any mention of free nutation and just redirect the page titled free nutation to this article without adding any information about free nutation to this article; which, since the definition appeared to be wrong, might have been a good idea; however, having a redirect to nothing here, was useless. And, nutation is used differently from free nutation, and free nutation is still not developed in this article, which is itself, disorganized and fails to offer a general understanding of what nutation is, much less free nutation, and where it is used in the introduction. But, I am used to this, "Get away from my article! we already decided how to fix it based on faulty evidence and without doing what we said we were doing and without knowing what we did" Wikipedia syndrome. I was okay with writing an article on free nutation, but, since nobody wants a definition of free nutation, whatever. -68.107.137.178 (talk) 16:56, 8 May 2013 (UTC)
replies: text: If you don't make it clear what you are trying to do, how can you expect to get cooperation? If you want to write an article, and not just restore a dictionary definition, I'm all for it. However, it might be better to improve this article first (I agree that it needs plenty of work). RockMagnetist (talk) 17:08, 8 May 2013 (UTC)
replies: text: It's not as if anyone here is clear; we have a disagreement about an incorrect definition that got turned into a merge that was just a redirect to an article that doesn't mention the topic. What's clear about that? What I did was an improvement, and since it is hard to figure out what was done here (not what you think was done, by the way), there's a limited amount of conversation I can have without spending an extensive amount of time trying to figure out what the consensus really was. I am not the least interested in nutation, only free nutation. -68.107.137.178 (talk) 17:44, 8 May 2013 (UTC)
replies: text: I don't think you have read the above consensus correctly, but does it really matter? There is now exactly as much information on free nutation in this article as there was in your last non-direct version of Free nutation. Even if there were a separate article on free nutation, this article should include a summary of it. So why not  start by adding a section on free nutation in this article? Then, if it grows long enough, split it. No one would object to that. RockMagnetist (talk) 18:03, 8 May 2013 (UTC)
thread_title:  Merger proposal 

message: I think the section on Physiology should remain here because there needs to be a note that it is a different concept, and that is all there is here. Does anyone have any objections to me removing the tag? Op47 (talk) 19:13, 9 February 2013 (UTC)
replies: text: Removing what? The Nutation #Physiology is a part of an entire problem. Possibly, this section has some relevance to Nutation (engineering), but not to the rest of "article". Incnis Mrsi (talk) 22:16, 9 February 2013 (UTC)
thread_title:  Split (Sacrum) 

message: I think the formula for kinetic energy T in Rigid body dynamics got an extra term. Should be just 
﻿T =... + \frac{1}{2}I_3\left(\dot{\psi})^2, 
no \dot{\phi}\cos\theta\right)^2.﻿  — Preceding unsigned comment added by David Gurarie (talk • contribs) 06:09, 24 August 2013 (UTC)
thread_title:  Correction 

message: Please only vote in the survey section and use the section "threaded discussion" for any discussion that may be required.
*Support option 1, I think this option is best; if somebody can demonstrate that the engineering and physics definitions are of equal precedence, I would be willing to change my vote. Of course, a hatnote would be needed at the top of this article. StringTheory11 (t • c) 05:38, 26 December 2013 (UTC)
thread_title: Survey

message: called for consistent approach for the articles. IMHO we now moving towards it.
* Precession is a WP:CONCEPTDAB (one said: covers multiple definitions) about several types of “rotation superposed with another rotation”. Namely:
** Axial precession;
** Nodal precession (similar thing, but for an orbital motion);
** Apsidal precession (two “rotations” in the same plane: an elliptic Keplerian orbit rotates itself).
*: Note that each of three types has its own article.
* Nutation has to be an article about changes in the axis of rotation that are not another rotation. There aren’t so many flavours of nutation, so  articles are not needed.
* All other types of rotational motion should require more articles, or be merged with appropriate context articles and be navigable from dab pages.
In short: the precession article does not appear to be such a mess. Incnis Mrsi (talk) 10:09, 29 December 2013 (UTC)
thread_title: Analogies with precession