Talk:Roche limit/Archive 1

message: The third of the series of images might be more instructive if the view was down the normal to the orbial plane, rather than in the orbital plane. That way in the destruction shot pieces in inner orbits can be seen to move more rapidly than pieces in outer orbits. This might (possibly) help with people's mis-perceptions regarding centrifugal force, etc. -- Kop 21:57, 2 Sep 2004 (UTC)
thread_title: Figure viewpoint

message: I reverted this sentence: "However, an object resting on the surface of such a body and held in place only by that body's gravity could find itself pulled away by tidal forces." (emphasis mine).  It had been changed to say "would" which is incorrect.  If the object is on the limb of the body as viewed from the planet, then tidal forces will actually tend to hold it on the body's surface.  --Doradus 18:18, 30 Aug 2004 (UTC)
replies: text: I'm not exactly sure what you mean by a limb, but you're right that the position on the moon is relevant.  On a rigid, tidally locked prolate spheroid moon in a circular orbit within the Roche limit, an object placed on the axis would "find itself pulled away"  but one placed on that moon's equator would not. --Noren 22:05, 30 Aug 2004 (UTC)
replies: text:  The limb of a celestial body is the edge of its apparent disk.  For a spherical body, this is (roughly) the great circle normal to the line of sight passing through the body's center.  This is not the same as the equator, which is the great circle normal to the axis of rotation.  --Doradus 03:23, 31 Aug 2004 (UTC)
replies: text: Urhixidur is taking this article in a very verbose direction.  This "sub-primary pole" part is tangential and distracting, and still doesn't warrant changing the "could" to a "would".  I'm sure if I try I can think of other reasons that an object on the surface would not be pulled away, even at the sub-primary pole (say, local gravitational anomalies).  I'd rather just keep it simple and leave it as "could".  --Doradus 16:42, 31 Aug 2004 (UTC)
thread_title:  Objects on the planets surface don't necessarily fly away 

message: I have changed the last table to make it (what I consider) more legible.  If people don't like it, I'll revert it (or you can :-). --Doradus 18:23, 1 Sep 2004 (UTC)
thread_title:  Orbit to Roche limit ratios 

message: We don't discuss at all in the non-heavy-math sections that the radius changes linearly based on the density.  Perhaps a line somewhere stating that the denser the moon, the greater the self-attraction is, resulting in a smaller Roche limit? --Noren 23:52, 1 Sep 2004 (UTC)
thread_title:  Roche limit dependancy on density discussion? 

message: Please, Noren and William, quit reverting each other.  You clearly disagree on which version is best, but until we resolve that question, neither version is so superior as to justify the continual reversions.  Both of you just please leave the article alone until we reach a concensus. --Doradus 02:27, 5 Sep 2004 (UTC)
replies: text: (William M. Connolley 13:24, 5 Sep 2004 (UTC)

text: Well it's not really my place comment extensively since you both know far more about the subject than I do. However  I did not assume the body was orbiting when I drew the first set of images, nor when i started the derivation. The web sites I looked at all said that to calculate the limit, balance the tidal forces with the self gravity. There was no mention of any other forces. I suppose it depends on how you define ther Roche limit - is it the point at which tidal forces break up a sattalite, or is it the point at which a true sattelite would actually break up? How did Roche define it himself? Theresa Knott  (Nate the Stork) 14:38, 5 Sep 2004 (UTC)
replies: text:  I agree with the jist of your point: that we should find some kind of existing authoratative definition.  Often scientists don't define the terms that bear their names.  For instance, you couldn't ask Newton what the term "newtonian physics" means; it's a term defined by later generations of scientists that differentiates Newton's views from those that came before and after.  So don't be surprised if you can't find a good answer from Roche's own pen, and you must look elsewhere.  Encyclopedia Britannica is the most authoratative citation I have seen so far, for what that is worth. --Doradus 03:09, 7 Sep 2004 (UTC)

text: (Later)
Quote from  explaing the now out of favour James Jeans theory of the formation of the solar system.
 "Jeans theory doesn't involve the previously mentioned solar prominences. 
 Jeans Theory instead involves the star passing within the Roche limit 
 (The distance from the centre of a body, within which a second body would
  be broken up by gravitational distortion) to release solar material from the Sun.
 This theory had trouble in explaining the angular momentum difference
  between the Sun and planets."
In this example the star is not orbiting the sun, yet is passing with the Roche limit  of it and therefore breaking up. So I think it's reasonable to say that it's not necessary for a body to be in orbit for us to talk about a Roche limit. Theresa Knott  (Nate the Stork) 15:11, 5 Sep 2004 (UTC)
thread_title: The "orbit" edit war

message: I hate to critique such nice pictures, but I find the debris a little hard to see.  Particularly in the 4th picture and the reddish debris in all the images.  On a related note, I wonder whether the contrast in tone is enough that someone who's color blind could see the images.  (I'd guess that converting them to black and white and seeing how they look would be the appropriate test.)  Also, the rightmost arrow in the 4th picture does not seem to be pointing along a circular orbit.  None of these are big problems, but it seemed worth pointing them out while the images are fresh-on-the-mind.  -- kop 19:33, 5 Sep 2004 (UTC)
thread_title:  Debris a little dim? 

message: Great work on this article to those who have contributed.  I especially like how it explains everything thoughtfully, *BUT* also has advanced mathematical concepts at the end for more indepth look.  Many of the mathematics articles *ONLY* have the advanced stuff since explaining it thoughtfully in layman's terms is the hardest part :).  Good work everyone! --ShaunMacPherson 01:20, 17 Oct 2004 (UTC)
thread_title:  Great work comments 

message: All the drawings appear to make sense to me if we regard them as views from above the orbital plane. I think that choosing this single POV is less likely to confuse readers. Or am I missing something? -- Karada 12:15, 17 Oct 2004 (UTC)
thread_title:  Viewpoint for drawings 

message: Substituted at 15:41, 1 May 2016 (UTC)
thread_title: Assessment comment