submission by jtoy
function setup(){
  var myCanvas = createCanvas(windowWidth,windowHeight); //you must keep this line unmodified
  strokeWeight(5)
 r = 5
 colors=[color(255,0,0),color(255,127,0),color(255,255,0),color(0,255,0),color(0,0,255),color(75,0,130),color(139,0,255)]
  background(0)
  rt=0
}

function draw() {
  t=millis()/10
  translate(width/2,height/2)
  strokeWeight(random(3,8))
  var c = colors[rt%colors.length];
  stroke(c)
   x= cos(t)*r
   y = sin(t)*r
   point(x,y)
   r+=0.1
  rt+=1
}