Gustav Holst's "The Planets" is a suite of seven orchestral movements, each representing a planet in the solar system (except for Earth). Holst did not include Earth in his work.

Here's why:

* Holst's focus: Holst was primarily interested in exploring the mythic and astrological interpretations of the planets, not their scientific aspects.

* Earth's lack of mythical association: In classical mythology, Earth (Gaia) was seen as a goddess, but she was not a prominent figure in the astrological interpretations that influenced Holst's work.

* Compositional balance: Holst felt that including Earth would have disrupted the overall balance and structure of the suite. He wanted to focus on the more prominent planets in astrology and mythology.

Although Earth isn't included, some argue that the seventh movement, "Neptune", could be interpreted as representing the earth's atmosphere and the vastness of space, but this is purely a personal interpretation.