ether

float theta, radius = 200, max=40, min=20;

void setup() {
  size(800, 600);
  background(255);
  rectMode(CENTER);
}

void draw() {
  float x = 400+cos(theta)*radius;
  float y = 320+sin(theta)*radius;
  float sz = map(sin(theta*3),-1,1,min,max);
  fill(20,10);
  stroke(220,150);
  noStroke();
  ellipse(x,y,sz,sz);
  theta += .0523;
  max += .5;
  min += .1;
  if (max>160) max = 160;
  if (min>40) min = 40;
}