var angle = 0;
var radius_x = 120;
var radius_y = 50;
var ang_velocity = 5;

var y = 0;
var x = 0;

moveTo(Stage.width/2 + radius_x, Stage.height/2);
lineStyle(2,0xFF0000,100);

onEnterFrame = function (){
x = Stage.width/2 + radius_x*Math.cos((angle*Math.PI)/180);
y = Stage.height/2 + radius_y*Math.sin((angle*Math.PI)/180);

angle += ang_velocity;
lineTo(x,y);
}