* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
.system {
  display: flex;
  width: 100vw;
  height: 100vh;
  align-items: center;
  justify-content: center;
}
.planets {
  position: relative;
}
.planets:after,
.planets:before {
  content: "";
  position: absolute;
  border-radius: 50%;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  border: 1px solid rgba(0,0,0,0.1);
}
.planets:before {
  width: 220px;
  height: 220px;
}
.planets:after {
  width: 280px;
  height: 280px;
}
.sun {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  background: orange;
}
@keyframes orbit1 {
  from {
    transform: rotate(0deg) translateX(110px);
  }
  to {
    transform: rotate(360deg) translateX(110px);
  }
}
@keyframes orbit2 {
  from {
    transform: rotate(-90deg) translateX(140px);
  }
  to {
    transform: rotate(270deg) translateX(140px);
  }
}
.planet-1,
.planet-2 {
  position: absolute;
  z-index: 1;
  border-radius: 50%;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  margin: auto;
}
.planet-1 {
  width: 40px;
  height: 40px;
  background: green;
  animation: orbit1 10s linear infinite;
}
.planet-2 {
  width: 20px;
  height: 20px;
  background: brown;
  animation: orbit2 15s linear infinite;
}