Small, dark, extremely cold and utterly lifeless, Pluto has always been considered the furthest planet from the Sun. But it is no longer defined as a planet, but rather a Plutonic object. It is best understood as the largest known member of the Kuiper belt, a band of rocky, icy miniplanets that orbit the sun in a swath stretching from beyond Neptune to a distance of nearly 5 billion miles. It takes 247 years to travel once around the Sun, and all material on it, rock, metal gas, or liquid is frozen solid. From its surface the Sun will appear only as a largish star, providing neither warmth nor comfort. It is a world of awesome desolation.

Artist's rendition of the Pluto surface, courtesy NASA