Outer solar system planets. Computer artwork and diagram of the orbits of the outermost four planets, and also the asteroids. This overhead angle looks down on the planets, which are: Neptune (lower right), Uranus (upper centre), Saturn (upper left), and Jupiter (upper right). The asteroids are seen inside the orbit of Jupiter. These four planets are known as the gas giant planets, as opposed to the smaller, rocky inner planets (not shown). The outer solar system (from Jupiter to Neptune) covers a radial distance of around 3.6 billion kilometres.