Celestia Forums

Just wanted to know if anyone knew what any of these items do in the scc file:

Period =
SemiMajorAxis =
Eccentricity =
Inclination =
AscendingNode =
ArgOfPericenter =
MeanAnomaly =
Epoch =
Obliquity =
Albedo =
RotationPeriod =

Need to know to continue working on my starwars addon.

Simple run down

Period = time it takes to revolve around an object
SemiMajorAxis = distance from the object it revolves around
Eccentricity = offset it gets closer or further from an object
Inclination = orbit is tilted this much
AscendingNode = think it has to do with position on the z axis...up and down relative to the object it faces
ArgOfPericenter = not sure
MeanAnomaly = not sure
Epoch = not sure
Obliquity = not sure
Albedo = brightness of the object...amount of sunlight it reflects
RotationPeriod = period of rotation on its axis

I would mess around with the variables and see what you come up with...best way to learn...

Thanks soo much, this will help a lot when i start to work on the orbital positions of the ships in the starwars addon. as for anyone else who may know about the other items:

AscendingNode =
ArgOfPericenter =
MeanAnomaly =
Epoch =
Obliquity =

let me know what they are. By the way, how are the 3ds files goung?

I am sure Obliquity is the degree and object or plannet is tilted on its axis while in orbit around the sun. Earths Obliquity of Ecliptic, meaning the angle of tilt in comparison to the ecliptic is 23.45 degrees as seen in the solarsystem.ssc file and Uranus' almost has a 97 degree obliquity.
I think MeanAnomaly is how out of round a planets orbit is. Can't be sure about that one. Epoch is a mesure of time or a placment in time as far as I can tell. Anyone got a better idea?

http://www.bdl.fr/solarsys/projet/glossaire_eng.html

AscendingNode= longitude of the intersection point of the orbital plane (node line) with the equatorial plane
ArgOfPericenter= longitude of the perigee with respect to the line of node

MeanAnomaly= position of the object in its orbit (from 0 to 360 degree with respect to perigee)

Epoch= date of these orbital elements (by default 1st jan 2000)

Obliquity= inclination of the rotation axis of the object (for this see :
[url]http://members/fortunecity.com/guilpain/images/Rep?re3d3.jpg[/url]
[url]http://members/fortunecity.com/guilpain/images/Rep?re3d3.jpg[/url])

Don't know if this is grammaticaly correct but it is a translation of the french site I made about the ssc file :
[url]http://members.fortunecity.com/guilpain[/url]

Sorry, this message didn't display very well and the links don't seems to be working, so just go to my website and I will add these images very soon !

AscendingNode, ArgOfPericenter, MeanAnomaly, and Epoch are all used for describing elliptical orbits. Here's a decent introduction to orbital elements.

http://spaceflight.nasa.gov/realdata/elements/

Obliquity is the angle between a planet's rotation axis and the ecliptic plane of the solar system (which in our solar system is defined to be the plane of Earth's orbit)

--Chris

Many thanks to everyone!