The Tenth Planet of malevolent cyborgs that became a recurring adversary in later "Doctor Who" stories. The "tenth planet" in the title makes reference to a fictional lost planet in Earth's Solar System; at the time of production, the Solar System was generally held to consist of nine planets, prior to the redesignation of Pluto as a minor planet. "The Tenth Planet" is an incomplete "Doctor Who" serial – one of many serials that were affected by the BBC's policy of wiping archived programmes in the 1960s and 70s. Only three of the four episodes are currently held in the BBC archives; the
The Planets before Holst's death, and was hailed by astronomers as the ninth planet. Holst, however, expressed no interest in writing a movement for the new planet. He had become disillusioned by the popularity of the suite, believing that it took too much attention away from his other works. In the final broadcast of his Young People's Concerts series in March, 1972, the conductor Leonard Bernstein led the New York Philharmonic through a fairly straight interpretation of the suite, though he discarded the Saturn movement because he thought the theme of old age was irrelevant to a concert for children. The broadcast