Solar System bodies are of many kinds. Planets and comets are certainly very different, but there may well be a link between comets and small asteroids; it is widely believed that some small asteroids are the cores of old comets which have lost all their volatiles, and that one of these, Phaethon, may be the parent of the Geminid meteor stream. There are a few bodies which have “dual nationality” and the distinction is not so clear-cut as used to be thought. The Deep Impact probe to Tempel 1 was immensely informative. One surprise was the abundance of organic material. As expected, the comet was made up chiefly of ices, with water dominant and plenty of ices such as methanol and carbon dioxide; assembling it must have been a gentle process. But what about more massive bodies which in some ways behave like comets? Chiron, which spends most of its time between the orbits of Saturn and Uranus, is well over 50 miles in diameter and has been given an asteroid number (2060), but when it draws into perihelion, it develops what may be called either an atmosphere or a coma and has also been given a cometary number, though to me this seems irrational. And then what about Pluto, way out in the Kuiper Belt?