Pluto and Charon. Illustration of the surface of Pluto with its moon Charon in the sky at upper left. An ice volcano is erupting at centre left. Pluto orbits some 6 billion kilometres from the Sun (centre right). In 2015, it will be visited for the first time by a spacecraft from Earth, with the New Horizons spacecraft flyby due to take place on 14 July 2015. Pluto is just 2300 kilometres is diameter, far smaller than the Moon. Charon is about 1200 kilometres in diameter and less than 20,000 kilometres from Pluto. Pluto, a dwarf planet, is considered to be a Kuiper Belt Object, not a true planet.