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
Astrology suite "The Planets". Written by the British composer Gustav Holst (1874–1934), and first performed in 1918, the framework of "The Planets" is based upon the astrological symbolism of the planets. Each of the seven movements of the suite is based upon a different planet, though the movements are not in the order of the planets from the Sun. The composer Colin Matthews wrote an eighth movement entitled "Pluto, the Renewer", first performed in 2000. In 1937, another British composer, Constant Lambert, wrote a ballet on astrological themes, called "Horoscope". In 1974, the New Zealand composer Edwin Carr wrote "The Twelve