theModel.js

//Our global variables
let earth;
let moon;
let r = 225;

function setup() {
  createCanvas(640, 640);
  //Creating our Earth and Moon
  earth = new Planet(createVector(width/2, height/2), 1000, 100, 'blue');
  //Notice we're starting the moon directly 'east' to our Earth, so the initial velocity is straight upwards.
  //Feel free to experiment with this initial velocity to see how it affects the orbit
  moon = new Satellite(createVector(width/2 + r, height/2), 10, 50, 'white', createVector(0, -4));
}

function draw() {
  //Clear the canvas
  background(0);
  //Draw the Earth
  earth.show();
  //If the Moon is close enough to the Earth, apply the force
  if(getDistance(earth, moon) <= r) {
    moon.applyForce(centripetalForce(moon, earth.position));
  } 
  //Update the moon
  moon.update();
  //Render it to the canvas... and then loop back to the start
  moon.show();
}