Talk:Orbital elements

message: This is overlapping Orbit#Orbital_parameters Kwantus 21:59, 2 Sep 2004 (UTC)
thread_title: Overlap

message: A discussion on the inspiration behind the selection of the orbital elements must be mentioned Iyer.arvind.sundaram (talk) 04:21, 11 June 2010 (UTC)
replies: text: Perhaps that would improve the article.  If you have a source, please do add such a discussion.  N2e (talk) 14:44, 28 December 2014 (UTC)
thread_title:  Inspiration 

message: The initial enumeration of orbital parameters lists the "true anomaly" as the parameter to determine where on the orbit the object is. However, the very next sentence explains the "mean anomaly" as if it was a term that was previously used. The section "alternative parameterization" goes on saying "instead of the mean anomaly, ...".  All of this makes it sound like someone wanted to write "mean anomaly" in the initial enumeration of parameters.  — Preceding unsigned comment added by 46.19.152.35 (talk) 13:09, 16 April 2017 (UTC)
thread_title:  True/mean anomaly in initial enumeration 

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thread_title:  External links modified 

message: I was curious about orbital elements of satellites, doesn't look like anything on Wikipedia. I found this Satellite Orbital Parameters which seems similar but adds some "Rate of change" of perigee, ascending node among others. If there's a standard, it would be good to add somewhere here. Tom Ruen (talk) 01:01, 8 September 2017 (UTC)
thread_title:  Satellites 

message: I wanted to test the math shown claiming that the generalized Rotator R can be composited by using 3 Euler angle (single-axis) transforms.
Just to be clear about assumptions:  I'm assuming that the orbit path begins abstractly as an elliptical path in 2D.  Periapsis is located on the +x-axis, the focus closest to it at the origin, and the apoapsis and more distant focus on the negative x-axis.  Also, I'm assuming the circulation direction is standardized in the abstract 2D coordinates -- with circulation of the orbiting body always circulating CCW wrt the +z-axis.
In testing the formulation given (to convert inclination angle, longitude of ascending node angle, and argument of periapsis angle into a 3 x 3 rotational matrix R), my assumptions held up for the case of positive inclination angles < 180, but failed for negative inclination angles.  
The article is vague and incomplete about the precise meanings of the 3 angles.  Each of these Keplerian angles should have a number range given, and indicate how the sign of the angular measure is defined.  For instance, let's take the "argument of periapsis".  Clearly, a value of 0 degrees indicates that periapsis coincides with the ascension node.  We might also infer that, for prograde orbits, the argument of periapsis increases in the direction of travel of the orbiting body, or CCW in the reference x-y axis system. In this case, both ways of defining positive angle increase agree.  However, what if the orbit is retrograde (CW circulation in the reference x-y frame)?  Does "argument of periapsis" increase positively in the direction of object travel?  Or, is the sign of the angle based on angular measure in the x-y frame?  These two definitions conflict.  So, the article is incomplete to fail to mention, for each angular element, how positivity is determined for measuring the angle. 
It's difficult to critique this article's math in words only.  When with complex 3D geometries, graphics are very helpful.
I'm wondering if people agree that the math in the article should be tested with software, and proven to "work" correctly with ALL possible cases of orbits?  My assertion is that, since an authoritative article will be taken as a software math spec, then it should address all possible cases of input (every possible elliptical orbit path).  — Preceding unsigned comment added by Pbierre (talk • contribs) 22:44, 11 December 2017 (UTC)
thread_title:  Euler Angle triplet --> Rotator Matrix R math only works correctly for positive inclinations < 180 degrees 

message: Is anyone planning on creating an article like this one but about rotational elements? ➧datumizer  ☎  20:39, 20 September 2018 (UTC)
thread_title:  Rotational elements? 

message: This article, Orbital_elements#Keplerian_elements and Orbital plane (astronomy), don't describe their definition in regards to stars like the stat table for Sirius. As best I can tell those coordinates are defined as if looking down Ecliptic south axis, so inclination 0 is orthogonal ccw, and inclination 90 is perpendicular to view, and 180 is orthogonal cw orbits. Tom Ruen (talk) 02:40, 18 February 2019 (UTC)
thread_title:  Stellar systems

message: Ω is commonly used for longitude of the ascending node, ν or θ is commonly used for true anomaly, and ω is commonly used for argument of periapsis.
My question is, how common is it for ι (iota) to be used for inclination?
There is evidence for this at  Greek letters used in mathematics, science, and engineering#Ιι (iota).  Maybe it should be mentioned in the Orbital Elements article.  214.6.80.22 (talk) 22:27, 29 October 2019 (UTC)
thread_title:  Greek letters