JavaScript - Sistema solar en javascript

var sun = new Image();

var moon = new Image();

var earth = new Image();

var mars = new Image();

function init(){

  sun.src = 'https://mdn.mozillademos.org/files/1456/Canvas_sun.png';

  moon.src = 'https://mdn.mozillademos.org/files/1443/Canvas_moon.png';

  earth.src = 'https://images.vexels.com/media/users/3/152418/isolated/preview/098366e6994dd75ab46b47cd27b2c9d4-icono-de-planeta-tierra-by-vexels.png';

  mars.src = "https://i.dlpng.com/static/png/1817849_thumb.png";

  window.requestAnimationFrame(draw);

}

function draw() {

  var ctx = document.getElementById('canvas').getContext('2d');

  ctx.globalCompositeOperation = 'destination-over';

  ctx.clearRect(0,0,600,600); // limpiar canvas

  ctx.fillStyle = 'rgba(0,0,0,0.4)';

  ctx.strokeStyle = 'rgba(0,153,255,0.4)';

  ctx.save();

  ctx.translate(300,300);

  // Marte

  var time = new Date();

  ctx.rotate (((2*Math.PI)/60)*time.getSeconds() + ((2*Math.PI)/60000)*time.getMilliseconds() );

  ctx.translate(150,0);

  ctx.fillRect(0,-12,50,24);// Sombra

  ctx.drawImage(mars,-12,-12,20,20);

  // La tierra

  var time = new Date();

  ctx.rotate( ((2*Math.PI)/60)*time.getSeconds() + ((2*Math.PI)/60000)*time.getMilliseconds() );

  ctx.translate(255,0);

  ctx.fillRect(0,-12,50,24); // Sombra

  ctx.drawImage(earth,-12,-12,30,30);

  // La luna

  ctx.save();

  ctx.rotate( ((2*Math.PI)/6)*time.getSeconds() + ((2*Math.PI)/6000)*time.getMilliseconds() );

  ctx.translate(0,28.5);

  ctx.drawImage(moon,-3.5,-3.5);

  ctx.restore();

  ctx.restore();

  ctx.beginPath();

  ctx.arc(300,300,255,0,Math.PI*2,false); // Órbita terrestre

  ctx.stroke();

  ctx.closePath();

  ctx.beginPath();

  ctx.arc(300,300,150,0,Math.PI*2,false); // Órbita marciana

  ctx.stroke();

  ctx.drawImage(sun,0,0,600,600);

  window.requestAnimationFrame(draw);

}

init();