P luto's average distance from the Sun is 5.9 billion km (3.66 billion miles). But because of a high orbital eccentricity (0.249), it comes as near as 4.42 billion km (2.75 billion miles) and travels as far as 7.40 billion km (4.60 billion miles) from the Sun. This unusual orbit brings Pluto inside the orbit of planet Neptune during its close approach to the Sun. The actual orbital paths do not cross, however. The planet revolves around the Sun once every 248.4 Earth years. In 1988 a computer simulation revealed that the orbit of Pluto is chaotic which means that it is not completely predictable.