Gidday , First time here.

I just wanted to share this example of a solar system with planets and comets.

While it uses some real world data, its not accurate....may be later.  Regards Alan.

 

// new orbit example
//  nplanets and ncomets
import processing.opengl.*;
//

float timestep = 200.0 ;
float theta = 0.0;
int scl = 1;

// array of orbital info
String[] pname = {"SUN", "MER", "VEN", "STA", "EAR", "STB", "MAR", "P/2012 A3\nSOHO", "C/2012 S1\nISON", "C/2011 W3\nLovejoy"};
float[] pnum = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
float[] ecc =  {0, 0.206, 0.007, 0.009562656, 0.017, 0.004440, 0.093, 0.776, 0.995, 0.995}; // eccenticity
float[] au =  {0, 0.39, 0.72, 0.95539896, 1.0, 1.051887, 1.52, 2.568, 10.0, 78.68 }; // mean distance 1au
float[] rot = {0, 0.24, 0.62, 0.93326171, 1, 1.078152, 1.88, 4.12, 10.0, 10.0}; // period of rotation 1yr
float[] eqtr = {3.0, 0.382, 0.949, 0.1, 1, 0.1, 0.532, 0.1, 0.1, 0.1};   // 1 earth diam
float[] angl = {0.0, 29.124, 55.186, 259.41452171, 114.20783, 18.37796930629710, 286.537, 217.6673, 295.7576, 332.02321}; // perri

//
PFont fontA = createFont("SanSerif", 12);
PFont fontB = createFont("SanSerif", 16);
//

//  
void setup() {
  size(1024, 1024, OPENGL);
}

void draw()
{
 background(0);
 
 // Translate the origin point to the center of the screen
  translate(width/2, height/2)  ;
 
  ellipseMode(RADIUS);

  nplanets();  // draw planets
  ncomets() ;  // draw comets

    theta +=(0.00004109*(1+timestep));
  
}

void keyReleased() {
  //
  if (key =='x') { exit(); }
  if (key =='c') { background(0); }
  if (key =='[') { scl-=1 ; if (scl <= 0) {scl = 1;}}
  if (key ==']') { scl+=1 ; if (scl >= 100) { scl = 100;}}
  if (key =='-') { timestep-=100 ; if (timestep <= -1000) {timestep = -1000;}}
  if (key =='=') { timestep+=100 ; if (timestep >= 1000) { timestep = 1000;}}
}

void nplanets() {
  // draw planets
  for ( int np = 6 ; np > -1 ; np-=1 ) {  
    float e1 = ecc[np];
    float a1 = (au[np]*300  );
    float b1 = a1*sqrt(1-(e1*e1))  ;
    float c1 = a1*e1  ;
    float  l1 = (b1*b1)/a1  ;

    float r1 = l1/(1.0+(e1*cos(angl[np]+theta/rot[np])));
    float x1 = r1*cos(angl[np]+theta/rot[np]);
    float y1 = -r1*sin(angl[np]+theta/rot[np]);

    //draw orbit
    stroke(32); fill(255/(np+1),255/(np+1),16/(np+1),16);strokeWeight(2);  // transparent orbit plane
    ellipse(0, 0, r1/scl, r1/scl);

    // draw planet at orbit angle
    stroke(200, 200, 200);  fill(36*(np+1),36*(np+1),16*(np+1),255);
    ellipse(int(x1)/scl, int(y1)/scl, (3*eqtr[np])/scl, (3*eqtr[np])/scl);
    //sphere((3*eqtr[np])/scl );
    stroke(255);  fill(255);
    textFont(fontA, 12); textAlign(LEFT);
    text( np+" "+pname[np], (1+int(x1)/scl), (-1+int(y1)/scl));
  }
}

void ncomets() {
  // draw comets
  for ( int nc = 9 ; nc > 6 ; nc-=1 ) {
    float ec = ecc[nc];
    float ac = (au[nc]*300 );
    float bc = (ac*sqrt(1-(ec*ec)))  ;
    float cc = ac*ec  ;
    float  lc = (bc*bc)/ac  ;

    float rc = lc/(1.0+(ec*cos(angl[nc]+theta/rot[nc])));
    float xc = (rc*cos(angl[nc]+theta/rot[nc]))+(2*cc);
    float yc = (-rc*sin(angl[nc]+theta/rot[nc]));
    // draw at orbit angles
    stroke(200, 200, 200); fill(200, 200, 200);
    ellipse(int(xc)/scl, int(yc)/scl, (3*eqtr[nc]), (3*eqtr[nc]));
    stroke(255); fill(255);
    textFont(fontA, 12); textAlign(LEFT);
    text( pname[nc], (1+int(xc)/scl), (-1+int(yc)/scl));
  }
}