One of the most popular works of 20th-century orchestral music, "The Planets" by Gustav Holst, had its first performance on this date in 1918. This was at a private concert at Queen's Hall, London, under the baton of Adrian Boult, who later became one of the most famous interpreters of this work. The first public performance of some excerpts from "The Planets" took place in February of 1919, after which the suite quickly became Holst's best-known composition. The great success of "The Planets" actually dismayed Holst, who feared it would create a demand for more orchestral works in the same vein, and Holst was always looking to do something new and different. He never considered "The Planets" anywhere near his best work, but none of his other works created anything like the sensation of "The Planets." This seven-movement orchestral suite is based on the symbolic astrological associations of the planets. There are only seven planets because Pluto had yet to be discovered when the music was written. This omission has recently been rectified by a contemporary English composer, Colin Matthews. At the request of conductor Kent Nagano, Matthews composed a "Pluto" movement, which had its premiere performance in England in May of the year 2000. Matthew's new piece has also been recorded, as you might expect, as a appendix to a new Hyperion recording of Holst's "Planets."