.a {
	width:400px;
	height:400px;
	border:1px solid red;
	border-radius:50%;
	background-color:red;
	position:relative;
	margin:200px auto;
}
.b {
	width:100px;
	height:100px;
	border:1px solid blue;
	background-color:blue;
	border-radius:50%;
	position:absolute;
	top:-50px;
	left:150px;
	animation:one 3s  infinite;
	transform-origin:50px 250px;
	position:relative;
}
.c {
	width:50px;
	height:50px;
	border:1px solid green;
	background-color:green;
	border-radius:50%;
	position:absolute;
	top:-55px;
	left:25px;
	animation:one 3s  infinite;
	transform-origin:25px 105px;
}
@keyframes one {
	100% {
	transform:rotate(360deg);
}
}