<head><style>
#M {
position: absolute ;
background: black ;
left: 100 ;
top: 200 ;
width: 100px ;
height: 100px ;
background: url("http://javascript.ru/forum/image.php?u=21338&dateline=1344715033") no-repeat center ;
background-size: contain ;
}
</style><script>
window.onload = function() {
var M = document.querySelector("#M") ;
var PI = Math.PI, p = 0.05 ;
PI = +PI.toFixed(2) ;
setInterval(function() {
var y = -Math.sin(PI), x = Math.cos(PI) ;
M.style.left = x*100+200 ;
M.style.top = y*100+200 ;
PI = PI + p ;
PI = +PI.toFixed(2) ;
if(PI==3.14||PI==6.29) p = -p ;
}, 50) ;
} ;
</script></head><body>
<div id="M"></div>
</body>
