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
Gustav Holst likens to "unresolved timelessness ... never ending, since space does not end, but drifting away into eternal silence". Apart from his concession with "I Vow to Thee..."', Holst insisted on the unity of the whole work, and opposed the performance of individual movements. Nevertheless, Imogen wrote that the piece had "suffered from being quoted in snippets as background music". During and after the composition of "The Planets", Holst wrote or arranged numerous vocal and choral works, many of them for the wartime Thaxted Whitsun Festivals, 1916–18. They include the "Six Choral Folksongs" of 1916, based on West Country tunes, of