Tomorrow marks the arrival of the New Horizons mission to Pluto mission to Pluto probe at Pluto, the largest dwarf-planet in the kuiper belt. It'll mark the end of a nine and half journey for the intrepid probe that was launched into space on January 19th, 2006. In the time its taken to get there, Pluto has been downgraded from being a planet to being a dwarf planet because its orbit round the sun isn't clear of objects. So far we have learnt is that Pluto is bigger than we thought it was, it is 2,370 Km in diameter. More details are coming out all the time and we should hopefully see some better photos. Here's a photo of Pluto with its bigger moon, Charon, not to scale and what we know of it at the moment.