"Neptune, the Mystic," was the seventh and last planet he featured as a movement of his work (Earth was excluded for astrological reasons and Pluto was not yet discovered to even be considered a planet). Holst saw Neptune as the most transcendent and distant planet of all. He captured that mysticism with long, lyrical phrases featuring various winds and an eight-part women's chorus.
Listen to a recording of "Neptune" below, performed by the BBC Philharmonic, and then hear the BYU Women's Chorus and the BYU Philharmonic Orchestra present the full suite on Nov. 17 in the deJong concert hall (http://www.byuarts.com/).
FYI: The female chorus begins singing at about 4:27 in the video and breaks into the eight-part harmonies at about 5:05.