float r = 200;
float a = 0;
float a1 = 360;
float r2 = 0;
void setup()
{
background(122,122,122);
size(600,600); 
}

void draw()
{

noFill();
arc(250,250,450,450,0,2*PI);

a+=5;

r2 = int(random(200));
fill(int(random(255)),int(random(255)),int(random(255)));
ellipse(250+r2*sin(a*(PI/180)),250+r2*cos(a*(PI/180)),10,10);

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

}