Space-themed music is any music, from any genre or style, with lyrics or titles relating to outer space or space travel.
Songs or other musical forms influenced by the concept of outer space have appeared in music throughout history, both in instrumental and vocal pieces with lyrics. As early as Ancient Greece, Pythagoras believed in something called the "harmony of the spheres". He believed that since planets and the stars all moved in the universe according to mathematical equations that these mathematical equations could be translated into musical notes and thus produce a symphony. This idea was explored further throughout Western history under the theories of Musica universalis. Some more recent and widely different examples are The Planets by Gustav Holst, and the song "Space Oddity" by David Bowie. Outer space also appears as a theme in "space age" retro pop music, such as Stereolab's Space-Age Bachelor Pad Music.
Music about outer space attracts enthusiastic listeners from all walks of life. Some have created web pages to share their interests. NASA, JPL, and the US Governmental Centennial of Flight Commission even have a webpages showcasing and discussing music about outer space.   
Music about outer space
The same year, Tangerine Dream released their double album Zeit, featuring space-related track titles such as Birth of Liquid Plejades and Nebulous Dawn, as well as cover art depicting a solar eclipse. It is considered one of the first (possibly the first) Dark ambient albums.
Eduard Artemyev has made space-themed music, for example for a space film Solaris (1972), although his best known and successfully covered space-themed sounding piece might be the theme song for non-space film Siberiade (1979).
The Japanese musician Isao Tomita has produced many albums with space-based themes, such as The Planets (1976), his version of Holst's suite; Kosmos (1978); Bermuda Triangle (1979); Dawn Chorus (Canon of the Three Stars) (1984); Space Walk – Impressions Of An Astronaut (compilation, 1984); Mind of the Universe – Live at Linz (1985); Back to the Earth – Live in New York (1988); and Nasca Fantasy (supporting Kodo, 1994).
The Vangelis album Albedo 0.39 (1976) is entirely devoted to space, while a segment of Heaven and Hell (1975) was used as the theme to the PBS television series Cosmos by Carl Sagan. His work Mythodea: Music for NASA's Mars Odyssey Mission is reflective of his interest in space exploration. 
Mike Oldfield's 1994 album The Songs of Distant Earth was based on Arthur C. Clarke's SF novel Songs of Distant Earth. Pop songs also mention outer space, such as Chris de Burgh's "A Spaceman Came Travelling", the Bonzo Dog Band's "I'm the Urban Spaceman", David Bowie's "Space Oddity", Elton John's "Rocket Man", Major Tom by Peter Schilling, and Deep Purple's "Space Truckin'". To Our Children's Children's Children by The Moody Blues was a 1969 album inspired by spaceflight.
Several albums have featured music inspired by the Apollo space program. In 1983, Brian Eno with his brother Roger Eno and producer/recording artist Daniel Lanois, composed the score for the film For All Mankind, a documentary of NASA's Apollo program; an album of the music, Apollo: Atmospheres and Soundtracks, was later released. On The Orb's 1991 two-disc debut album, Adventures Beyond the Ultraworld, disc one of features an ambient musical simulation of the Apollo 11 moon journey, including excerpts of NASA recordings of the radio conversations between Mission Control and the astronauts in space.
Author and classical music critic David Hurwitz describes Joseph Haydn's choral and chamber orchestra piece, The Creation, composed in 1798, as space music, both in the sense of the sound of the music, ("a genuine piece of 'space music' featuring softly pulsating high violins and winds above low cellos and basses, with nothing at all in the middle ... The space music gradually drifts towards a return to the movement's opening gesture ... "); and in the manner of its composition, relating that Haydn conceived The Creation after discussing music and astronomy with William Herschel, oboist and astronomer (discoverer of the planet Uranus).
Another band to use space as musical inspiration is the Christian "Astro-Rock" group Brave Saint Saturn, whose three albums, So Far from Home, The Light of Things Hoped For, and Anti-Meridian, form a trilogy that chronicles the journey of the fictional spaceship, the USS Gloria, on a trip to survey the moons of Saturn. The music uses space narratives, lingo, samples and quotes to portray the journey.
Soundtracks for movies and TV shows about outer space
A Bach piece played by Italian thereminist Fabio Pesce on a Moog Etherwave theremin.
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Soundtracks of science fiction movies and television and radio series often feature music associated with outer space, such as Star Wars, Star Trek, Doctor Who, The Hitchhiker's Guide to the Galaxy, Red Dwarf, The X-Files, and others.
Music played in planetariums and observatories
Many forms of music are used Observatory and Planetarium shows, particularly genres such as Electronic music, classical music, Space music, and Space rock. Some artists, such as Geodesium, specialize in creating custom music for Planetariums.
During the 1970s, IMAX's OMNIMAX (now IMAX Dome) film system was conceived to operate on planetarium screens. More recently, some planetariums have re-branded themselves as "dome theaters," with broader offerings including wide-screen or "wraparound" films, fulldome video, and laser shows that combine music with laser-drawn patterns.
Music made with sounds of outer space
Objects in space – the Sun, planets, stars, quasars, pulsars, galaxies, and active galaxies – all produce signals that, if received (usually through radio astronomy dishes and processed), can be used by a musician as the basis for any kind of composition imaginable. 
Scientists with an interest in space-based sounds include:
- Don Gurnett.
- Stephen P. McGreevy.
- Alexander Kosovichev, a Stanford scientist whose researches into the Sun's oscillations (and who uploaded the sounds to the net) encouraged Stephen Taylor (see below) to create his album.
- Dr. Fiorella Terenzi has created several works that use sounds derived from celestial radio signals homepage, Space.com entry.
- NASA produced a CD in 1992 from Voyager 1 & 2 recordings of electromagnetic fields processed with digital sampling techniques.
Artists/bands who have included such sounds in their works include:
- Terry Riley, along with the Kronos Quartet, in their album Sun Rings, which used "sounds of the planets recorded by the Voyager mission on its journey to deep space" .
- Stephen Taylor, in the album The Heart of the Sun.
- Robert Schroeder's album Galaxie Cygnus-A used interstellar noise from the distant galaxy in the title 
- The Musical Sounds of Space – NPR Arts & Culture
- Music Space – Listening to the cosmos ...
- From outer space, music of peace – Providence Journal
- Outer space as a muse Milwaukee Journal Sentinel
- Lon Strickland's space-themed synth-pop album
- Mars Artists Community
- Riedweg, Christoph (2005). Pythagoras: His Life, Teaching, And Influence. Cornell University Press. pp. 29, 30, 116. ISBN 0-8014-4240-0.
- http://www.nasa.gov/home/hqnews/2003/dec/HQ_03396_Labelle.html ASA Song Soars To Grammy Nomination
- http://saturn.jpl.nasa.gov/news/press-releases-00/20001215-sn-a.cfm "Sounds" of Outer Space Near Jupiter Now Online – JPL/NASA website
- http://www.centennialofflight.net/essay/Social/music/SH16.htm Aviation and Space Music – U.S. Centennial of Flight Commission
- NASA Spotlight on Vangelis music for Mars Odyssey Mission
- Prendergast, Mark (2000). The Ambient Century: From Mahler to Trance – the Evolution of Sound in the Electronic Age. Bloomsbury Publishing, New York. p. 125. ISBN 1-58234-134-6.
- Hurwitz, David (2005). Exploring Haydn: A Listener's Guide to Music's Boldest Innovator. Amadeus Press Unlocking the Masters Series. Hal Leonard. pp. 78–81. ISBN 1-57467-116-2.
- Enthusiast's website with detailed information about music for Planetariums and generally about outer space
- space weather glossary sounds information
- NASA space-sound poetry page
- here Hobbysapce article on space sounds used in music
- NASA Voyager CD
- electromagnetic fields processed with digital sampling techniques
- report on Voyager music by Kronos Quartet
- Stanford – Stephen Taylor album info
- The Music of Robert Schroeder
- AmbientMusicGuide.com – Robert Schroeder
- Robert Schröder – Galaxie Cygnus-A