Talk:Mean motion

needs work[edit]

Mean motion is not, in most cases, a time average. In particular, mean motion as part of osculating elements is an instantaneous value - if it were averaged over an orbit, with all of the perturbations, it would be quite a different value. The article seems to be (Earth-) satellite-specific. Needs to be generalized for any orbiting bodies. Tfr000 (talk) 01:16, 28 October 2015 (UTC)[reply]

In the Very First Equation we introduce three different definitions for the same variable n (mean motion)? That's terrible. — Preceding unsigned comment added by 192.31.242.195 (talk) 15:38, 22 July 2016 (UTC)[reply]

The point is simply to show that there is no need to constrain ourselves to radians, degrees, or anything in particular... see below, for instance. Maybe that's a mathematician's pet peeve, but it explains things more clearly. We're not writing a mathematics text here. Tfr000 (talk) 22:01, 16 June 2017 (UTC)[reply]

Derivations are more confusing now[edit]

In the section Mean motion and Kepler's laws, user 2601:281:8000:aa8e:c007:8158:1472:7b4a claims we "Fixed the derivation of mu=a^3n^2. Kepler's 3rd law was quoted wrong. Also, n needs to be radians per unit time, not revolutions for this form to work out right." Or, we could just leave it in revolutions like it was in the first place. That way we don't have to insert radians and then "Convert n to radians per unit time" to balance the equation. A whole lot easier to follow. Also, considering that Kepler likely wrote his law in Latin text, and not in an equation at all, there is no "right" way to quote it.

I will be changing the text back eventually unless there are objections to this. Tfr000 (talk) 21:42, 16 June 2017 (UTC)[reply]

Done. Tfr000 (talk) 00:35, 4 July 2017 (UTC)[reply]

I'm even more confused now. I suggest picking a system of angular measurement, I don't care which, making it explicit, and keeping it consistent throughout the article. --Ipatrol (talk) 02:28, 25 December 2018 (UTC)[reply]

Please verify the equations[edit]

When substituting the mean motion into Kepler's 3rd law, I believe you should use the radians per time form, not the frequency form. I guess you could use the frequency form, but then you can't call the proportionality constant μ, which is the Standard gravitational parameter. Also, the first equation is different from the text, and its use of proportionality is weird. I've changed the first 2 equations to correct those mistakes, but I don't have a book on celestial mechanics, so I request some further verification. Frlara (talk) 19:48, 24 April 2019 (UTC)[reply]