In order to get the real picture of an orbit, we have to see it in three-dimensional coordinate space.  The most common reference system for the earth orbiting bodies is the geocentric-equatorial earth coordinate system (see Basics).  For this system, there are six orbital variables that can produce a vast number of orbits with different shape, size, position and orientation.  I wrote a MatLAB program that will enable the user to visualize the orbit in three dimensions and hopefully be useful as a tool in developing a better understanding the effects of each one of the orbital elements. 

     The program begins by prompting the user for the six orbital elements described in the Basics.  As in the 2D program, the user can choose the default values by just pressing the enter key.  After the user enters the orbital elements, they are given the option of displaying the IJK vectors on the earth (bottom right figure).  The figures below both contain the earth (copper sphere), the 'P' (red), 'Q' (green), 'h' (yellow) vectors, and the path and position of the orbit as in the 2D program.

 
a:1.5, e:0.3, n:222, W:33, w:66, i:-33 
a:1.5, e:0.3, n:222, W:33, w:55, i:22
 
     These are just a couple of examples, if you would like to try some of your own cases, click here to download the file: 'orbit3d.m'  A helpful way to begin to understand what each orbital element does is to change one element at a time and observe the effects.  To use this program, simply copy the file into your MatLAB directory and type 'orbit3d' at the MatLAB prompt. 

     To see an orbiting body in motion, click here: 'animation.'  You can also type in the command 'comet3(ri,rj,rz)' at the MatLAB prompt after using 'orbit3d' to see the path of the orbit traced out. 
 

 


 
Introduction Background Basics 2D Viz 3D Viz Tracking Conclusions