Talk:Celestial mechanics

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Please update this rating as the article progresses, or if the rating is inaccurate. Click to show/hide comments. Please add to or update the comments to suggest improvements to the article. Please add useful comments here--Cronholm144 10:20, 23 May 2007 (UTC)

Contents 1 Merging 2 Category consensus 3 Open Problems 4 Expansion 5 Circular Orbit Assumption 6 Neat little law:

[edit] Merging

Should this page be merged with Astrodynamics? [[User:Sverdrup|❝Sverdrup❞]] 10:06, 12 Sep 2004 (UTC)

Probably; the other celestial Mechanics page is just a older copy of it. --Ben Standeven

Reading the rules of the Wiki, Celestial mechanics is the preferred title, (as opposed to Celestial Mechanics) using the lowercase name of all but the first word in the title. The subjects of Celestial mechancis and Astrodynamcs are clearly separated: the former is the science; the latter engineering. The former, objects in free flight: gravity. The latter, the addition of non-gravitational forces such as drag and propulsion. -- Marty McGowan Nov 26, 2004.

[edit] Category consensus

The categorization shows that astrodynamics is a sub-cat of celestial mechanics; astrodynamics uses the principles of celestial mechanics, as its article states. This suggests that the notice be taken down. Ancheta Wis 09:56, 20 Apr 2005 (UTC)

I absolutely agree that the notice should be taken down, for reasons already mentioned (propelled vs unpropelled flight, engineering vs science) and others. Celestial mechanics is a highly mathematical subject, which includes questions such as: (1) is the solar system stable? (2) Are other planetary systems stable? (3) How do star clusters evolve (they cast out a few members and contract, but the details are important)? (4) If you have a binary system and a new member enters, can it be captured without ejecting one of the existing ones? (I think the answer is "no"). (5) under what circumstances will one find limited chaotic motion or unlimited chaotic motion in a multibody system? All this needs to be added or linked in here and would be a bore to engineers. Pdn 19:36, 24 Apr 2005 (UTC)

The notice should most definitely be removed. Celestial mechanics and astrodynamics are two distinct subjects, the one science, as has been said, the other engineering (as in spaceflight, for example). Having said, that, this page is not a good entry for Celestial mechanics. It comes at the subject too much from the point of view of astrodynamics. It's not good. Eilthireach 20:56, 19 May 2005 (UTC)

I agree entirely. This article is very poor, and there's too much spacecraft stuff in it which should be at astrodynamics. Also, is it really necessary for both articles to duplicate material on Kepler's equation? -- 80.168.226.10 15:27, 20 May 2005 (UTC)

1. Hohmann transfer orbit
2. Gemini 11 flight
3. suborbital flights

belong in Astrodynamics, not here Pdn 01:39, 21 May 2005 (UTC)

I agree that those three belong in astrodynamics Dpu2002 15:02, 16 June 2006 (UTC)

[edit] Open Problems

Some unidentified person has put in a section on "open problems" (if you hit her/his talk page it is a group page). I thought that it was proven a long time ago that you can't get an analytic solution for even the three body problem (except very restricted cases like Lagrange points). So I suggest this be deleted or rephrased. Anyway, it does not say "analytic" so it is ambiguous, too. Computer solutions exist for very many orbits but may fail long-term, although recently "symplectic methods" seem to handle that (e.g. for the life of the solar system so far). Pdn 01:34, 15 Jun 2005 (UTC)

[edit] Expansion

Um, I'm a bit confused about the talk above regarding "taking down the notice." I'm assuming that the discussion is concerning a merge/catagory notice, and not the expansion notice that was at the top of this page. I personally think the article should be expanded -- right now it's mostly history. With that, I'm moving the expansion request to the article itself. MFago 03:26, 18 March 2006 (UTC)

I just compounded the problem by tidying up the history section. I agree that there is a need for someone who really knows modern celestial mechanics to provide a good readable introduction to its fundamental concepts, principles, and methods. The examples of problems section is too rapid a jump without a good grounding in the nature of the discipline. --SteveMcCluskey 18:57, 22 January 2007 (UTC)

[edit] Circular Orbit Assumption

The section in the article describing the circular orbit assumption seems misleading. When I read it, I get the idea that circular orbits are assumed very often, when this is far from the case. Maybe its just me sucking at reading today, does anyone else think that? Dpu2002 15:01, 16 June 2006 (UTC)

[edit] Neat little law:

This is something about orbits I read a little while back, that might be appropriate in this article:

In order to slow down, you speed up; to speed up, you slow down.

Slowing down puts you into a lower orbit, which is faster in relation to a point on the surface of the body you are orbiting around. Speeding up puts you into a higher orbit, which is slower in relation to the aforementioned point.

Can anyone think of a place to put this?

Phædrus 00:05, 20 March 2007 (UTC)