Any reference site for realistic orbital parameters ?

[Mutos]

Hi everybody,


I just wrote the first planetary system for my SF universe, it's the cradle star for a nonhuman spacegoing species. But i got a big problem : don't know wether my orbital parameters are physically realistic : for instance, i remember st about major semiaxis & revolution time being linked (maybe in Kepler's laws), whereas in Celestia they are independant.

So is there a site where i can find the relevant equations or examples of parameter sets. I'll also search the web on my own but i think i'm not alone & a few links here could help lots of newbies.

I intend to develop a simple VB app for this purpose. Just a few boxes to write down the desired parameters & a "Go" button to translate them into a Celestia parameters set, ready to be pasted into a SSC file. Should be in a month or so as i'm going tomorrow on holidays far from any 'puter ^-^


Thanks in advance,

[Malcolm]

>major semiaxis & revolution time being linked (maybe in Kepler's laws)

I am not an expert, I think it is Tsquared % K.Rcubed
where % represents the proportionality symbol
T is the period and R is the radius (or distance from the primary). I am unsure if the radius equates to the semi-major axis or the mean radius for an elliptical orbit
The proportionality constant K includes the mass of the primary

>Celestia they are independant

Yes,I found this when I made a mistake in one of my .ssc files, I had two planets in similar orbits, one going round at 50times the rate of the other , amusing but not practical !!

>but i think i'm not alone & a few links here could help lots of newbies.

Including me
here is one that I found a couple of days ago while I was constructing my own planetary system
http://www.planetarybiology.com/
in particular I found this page on the site interesting
http://www.planetarybiology.com/astrono ... onom12.htm
If I go back and re-read that page I might be able to determine the correct R/semi-major thing.
Of course that site will only apply to you if your non-humans are also carbon-oxygen-water based life-forms !!

[ogg]

For anyone interested in knowing about orbits and orbital mechanics, I'd recomend the NASA online tutorial/course that they requre their employees to study. It's called 'the basics of space flight' and it's at:

http://www.jpl.nasa.gov/basics/toc.html

I haven't checked specifically, but I'm 90% sure that the answer to your question would be in there somewhere...

actually if you just want the maths involved, you can find better sites then this just by googling "kepler's laws"
eg

http://plabpc.csustan.edu/astro/kepler/laws.htm

[Mutos]

Hi everybody,


A great thanks for ur answers, lots of helpful thinks around the links.

Formula is right & w/ units it gives :

Tsquared (Years) = Rsquared (UA)

T is revolution time
R is half the semimajor axis, if i understand well...


Best regards

[Malcolm]

>you can find better sites then this just by googling "kepler's laws"

That is true, but at the time I was heavily into trying to fathom Celestia and TheGIMP (sigh)Don't, Beeblbrot, don't talk to me about TheGIMP oh no,, ohhh dear,,, ohhhgroan, , ,ohhh stomp stomp(/sigh)
So I thought a quick post about the planetarybiology.com would get him started ! Well, he was asking in relation to habitable planets after all

PS Mutos-- you still did not tell us if you were contemplating carbon based non-humans ?!
Here are some more :-
http://www.sunspot.noao.edu/PR/answerbook/expl-2.html
that one also has stuff about Lagrangian points that were the subject of another thread somewhere,,
and this one has some neato applets :
http://apollo.spaceborn.dk/orbitmech.html

ogg-- When I have mastered TheGIMP, I'll go and do that jpl.nasa one,,
honest,,, just as soon as I sort TheGIMP,,, oh groan

[Mutos]

Hi everybody,


I'll try to built entire planetary systems, w/ habitable & non-habitable planets. Anyway, all my lifeforms (for now...) are carbon-based so the planetarybiology & other links WILL be useful ^_*

For now i'm delayed for 2 reasons : 1st, got an emergency at my office that called me back from holidays :-(( 2nd is better, a French gaming site/TV called me Tuesday to chronicle Hoshikaze. They have 3000 visits/day, if only 1% goes to see Hoshikaze, this quadruples my 10 hits/day !!!

But it also means some work & delay for planetary systems. Anyway i'm still thinking 'bout that little vb GUI for parameters. Didn't have time to get to it, though ! The principle is to enter independant & meaningful parameters & have the GUI spit a complete SSC parameters set...

[felixx]

World Builidng by Stephen Gillett may offer some support. Although it may be a little watered-down for all those techies out there who like doing a lot of math, it's a good read and has a lot to say about planet's, their atmospheres, and the possibilites of life on strange exo worlds. I think it's out of print so you may have to buy it used. Check Amazon.com, they may have gotten new ones in.

Anyway, check it out.

Alex

[Mutos]

Thanks, just returned from some holidays, now i'll get to it !