"The Planets" is a piece for orchestra with seven movements - each named after a planet in the Solar System with the exception of Earth. Holst was interested in astrology and said that the music portrays the astrological significance of each planet. Each one has a title that gives an idea of what the music is about. Holst described the work as "a series of mood pictures".
Holst started writing the work as a piano duet in 1914 with the exception of Neptune which he wrote for organ because he did not think the piano sounded mysterious enough. He then changed the work to be for a large orchestra. The first full performance was in 1920 and presented by the London Symphony Orchestra. It was a huge success all over the world.

1. Mars, The Bringer of War
This movement begins with a dark repeated rhythm in an unusual meter that drives on and on. The strings play the rhythm by tapping the wood part of the bow against the strings. Then loud, powerful bass solos enter. The movement has a massive sound with many instruments playing at once, sometimes merging into a flurry of sound.
Holst composed "The Planets" when Europe was fighting WWI, and he supposedly once said that he wanted to express the stupidity of war in this movement. The "Imperial March" in Star Wars is probably inspired somewhat by this movement.

2. Venus, The Bringer of Peace
The mood of the second movement is the opposite of the first. The storm has passed and a new day is dawning. Instead of the full orchestra playing together, the music is delicate, soft, and slow with beautiful solos.

3. Mercury, The Winged Messenger
This is another delicate movement but much faster than Venus with bouncy, light scales running up and down. It is the shortest movement in the work (about 4 minutes) and features the strings and woodwinds. The music is playful and quick and switches from one instrument section to the next.

4. Jupiter, The Bringer of Jollity
Holst thought of a jolly person who enjoyed life when he wrote this music. Jupiter is probably the most famous movement. It may have been inspired in part by Holst's love of English folk dances.

5. Saturn, The Bringer of Old Age
This was apparently Holst's favorite movement. It is very different from the big, bouncy Jupiter. Saturn is a low, slow movement that begins in the strings and gradually adds instruments. It builds to a peak halfway through. Then it gradually slows down and becomes peaceful again.

6. Uranus, The Magician
This movement uses the entire orchestra. Imagine the magician as a giant walking through the sky. The trombones announce his entrance, followed by the heavy sound of the tubas. The music is bouncy and fast in places and loud in others.

7. Neptune, The Mystic
Here the music is soft and eerie and seems to glide along in the strings and woodwinds. One interesting effect is the wordless part sung by two choirs made up of female singers. Their parts blend in with the orchestra. Holst wrote that the choirs "are to be placed in an adjoining room, the door of which is to be left open until the last bar of the piece when it is to be slowly and silently closed." This fade-away effect was unusual at the time and fascinated audiences.