The Planets dedication notwithstanding, Imogen Holst "would have been both amused and dismayed by the venture." On 24 August 2006, the International Astronomical Union (IAU) defined what it means to be a "planet" within the Solar System. This definition excluded Pluto as a planet and added it as a member of the new category of "dwarf planets", along with Eris and Ceres. Following the IAU decision, Kenyon D. Wilson composed a trombone quintet piece titled "Songs of Distant Earth". The title comes from Arthur C. Clarke's novel of the same name. The composition contains five movements, each named after one of the
Inferior and superior planets Interior planet now seems to be the preferred term for astronomers. Inferior/interior and superior are different from the terms inner planet and outer planet, which designate those planets which lie inside the asteroid belt and those that lie outside it, respectively. Inferior planet is also different from minor planet or dwarf planet. Superior planet is also different from gas giant. Inferior and superior planets In the Solar System, a planet is said to be inferior or interior with respect to another planet if its orbit lies inside the other planet's orbit around the Sun. In this situation, the latter planet