float r = 200;
float a = 0;
float a1 = 360;
void setup()
{
background(122,122,122);
size(600,600); 
}

void draw()
{
fill(int(random(255)),int(random(255)),int(random(255)));
ellipse(250+r*sin(a*(PI/180)),250+r*cos(a*(PI/180)),10,10);

a+=5;

if (a > 360)
{
r = 200;
a = 0;
}

}