Before Galileo turned his telescope to the heavens, the planets of the Solar System were not widely recognized as worlds, or places where a person could potentially set foot; they were visible to observers merely as bright points of light, distinguishable from stars only by their motion.
In the system of Claudius Ptolemy (fl. c. 150), the Alexandrian astronomer whose works were the basis of all European astronomy throughout the Middle Ages and Renaissance, the planets were lights set into a series of transparent spheres turning around the Earth, which was the center of the one and only universe. Dante (1265–1321), in his Paradiso, describes the ascent of his narrator through the spheres of the Moon, the planets from Mercury to Saturn, and thence to the sphere of the fixed stars and the heavens of the angels. Dante implies that the light of the planets is a combination of light imparted by Divine will and the radiance of the blessed souls that inhabit the spheres. These planets are, however, entirely ethereal; they have light but no physical form and no geography.
Ludovico Ariosto, in his epic Orlando Furioso (1513), jestingly sent his hero Astolfo to a Moon where everything lost on Earth eventually turns up, guarded by Saint Peter; but it was not until Galileo discovered (1609–1610) that the Moon had surface features, and that the other planets could, at least, be resolved into disks, that the concept that the planets were physical places came to be taken seriously. In 1543, Nicolaus Copernicus had already posited that the planets orbited the Sun as the Earth does; combined, these two concepts led to the thought that the planets might be "worlds" similar to the Earth. Public expression of such concepts could be dangerous, however; Giordano Bruno was martyred in 1600 for, among other things, imagining an infinite number of other worlds, and claiming that "Innumerable suns exist; innumerable Earths revolve about these suns ... Living beings inhabit these worlds" in De l'infinito universo e mondi ("Concerning the Infinite Universe and Worlds", 1584).
At the time, such speculation was of a rather rarefied sort, and was limited to astronomers like Christiaan Huygens who wrote a book, Cosmotheoros (1698) considering the possibility of life on other planets; or to philosophers like Campanella, who wrote in defense of Galileo. The concept of life on distant planets was not, however, much utilized in fiction. The most popular target of 17th century "science fiction" was the Moon ("visited" in fiction by Kepler, Godwin, Cyrano, and Defoe). Oddly, none of these fictions made use of the lunar maps contemporaneously created by Hevelius, Riccioli and others.
It was quite some time before such "extraordinary voyages" went beyond the lunar sphere. Eberhard Kindermann sent an airship to the planets in 1744 in Die Geschwinde Reise auf dem Lufft-schiff nach der obern Welt ("The Airship's Speedy Journey to the Upper World"); while a traveller from the star Sirius passes inward through the Solar System, stopping at various planets in Voltaire's Micromégas (1752); followed by another outward voyage in Marie-Anne de Roumier-Robert's Voyage de Milord Céton dans les Sept Planètes ("Lord Seton's Voyage Among the Seven Planets", 1765). These stories were generally unscientific and tended towards the satirical rather than the purely entertaining; their subject-matter was probably inspired by the popular writings of Fontenelle, notably his Entretiens sur la pluralité des mondes ("Conversations on the Multiplicity of Worlds", 1686).
With the rapid developments in the magnifying and resolving power of telescopes in the course of the 19th century, it finally became possible to distinguish surface features on other planets and even to draw maps of some of them, notably Mars. In 1877, Asaph Hall reported two moons of Mars and Giovanni Schiaparelli found the surface of Mars to be adorned with continents, seas, and channels, and a very suitable habitat for life. From the beginning of the 1880s, fictions – some more, some less scientific – involving travels to and from Mars began to be produced in great quantities, even though the observations of Percival Lowell required reassessment of Mars as a more marginal desert planet. Mars remained a favored destination for fictional travellers down to the early 1960s (see Mars in fiction). Since probes revealed the absence of any indications of intelligent life on Mars, the science fictional Mars has changed to a possible future home for the human race, e.g. through terraforming.
Venus was never quite so popular as Mars, probably because it obdurately refused to display any surface features (it is covered with sulfuric acid clouds only dimly translucent to visible light), making any statement about its nature disturbingly speculative. In 1918, chemist Svante Arrhenius, deciding that Venus' cloud cover was necessarily water, decreed in The Destinies of the Stars that "A very great part of the surface of Venus is no doubt covered with swamps" and compared Venus' humidity to the tropical rain forests of the Congo. Venus thus became, until the early 1960s, a place for science fiction writers to place all manner of unusual life forms, from quasi-dinosaurs to intelligent carnivorous plants, and where hostile interactions with Venusian natives were reminiscent of European colonial projects in Africa and Asia (see Venus in fiction). In fact Venus's surface is hot enough to melt lead, and it is extremely hostile to life.
Various planets of the Solar System were used as settings for science fiction stories in the first half of the 20th century; but dissatisfaction with the limits imposed by science led many writers early on to forsake the Solar System for fictional planets around distant stars. As increasing knowledge of the Solar System made the prospects of life in the vicinity of Earth marginal at best, the extrasolar planet has become almost the only venue for contemporary science fiction.
In many works of science fiction, planets are only described casually, as points of origin and departure, or as interchangeable backdrops for space battles. This is particularly true of space opera. In other works, the planet is the center stage, the primary scene of events, and particular attention is paid to its environment and any culture that may exist there. Adventure stories that stick to a single, well-described planet are sometimes called planetary romances; some of these planets are not very realistic and are effectively fantasy worlds.
Planets may be treated in different ways depending both on the interests of the author and the genre they are writing in. In some stories, a planet is mainly considered as an object in space: the interest of the fiction depends upon its astronomical characteristics, such as its mass, its geological composition, its atmosphere, how many moons it has and what size they are, how close it is to its sun (or suns) and how hot they are. Such considerations are found prominently though not exclusively in the hard science fiction genre.
In other stories, a planet is considered as a world or setting. Such a planet will be described from the point of view of a person dwelling on it, rather than from the point of view of an outside observer: the fiction may describe its geography, its history, and the social and cultural characteristics of its civilizations. Since authors usually adopt human protagonists, such planets are typically described as very hospitable to human life and, other than in geography, nearly indistinguishable from Earth; Brian Stableford calls such planets "Earth-Clones". Conversely some fictional worlds are never more than marginally habitable, which has a profound effect on societies that developed or moved there. Numerous examples of this are to be found in the Known Space stories of Larry Niven.
In some works of fiction, such as Pournelle's CoDominium or Card's Ender's Game series, certain planets are settled by specific ethnic groups. However, in novels set in distant futures, e.g. Dune, the inhabitants have usually forgotten about the original settlers.
While some authors choose to treat a planet in depth, considering it to have a wide diversity of geography, climate, politics and culture, others prefer to characterize their planets by some single global characteristic. Many of these uniform settings have become stereotypes, used in a variety of science fictional works. Such stereotypes include: the planet covered by a single city; the planet whose surface is entirely desert; the planet covered by ocean, with no landmasses; the planet on which it is perpetually winter; the planet that is self-aware; and the planet which has been artificially constructed.
Other planets appear in humorous or comical settings, sometimes spoofing more conventional science fiction. Such planets are often described with no pretense to scientific accuracy; their strange characteristics are primarily intended to amuse.
For the Star Trek universe, a detailed planetary classification system has been devised; it is not actually used by scientists.
For planets from specific fictional milieux, use the following lists and categories:
For a more scientific approach to classifying planet types from Orion's Arm
Ice planets have figured prominently in science fiction, such as Hoth, an ice planet featured in The Empire Strikes Back, or Gethen, an ice planet in the novel The Left Hand of Darkness by Ursula K. Le Guin.
An ice planet named Fichina is featured in the Star Fox video game series.
Ancient Mesa (Ancient Mare in the Japanese version) is a venue in F-Zero Maximum Velocity. Its tracks includes the Split and Skating Circuits. Another ice planet appears in the name of White Land in every other F-Zero games. Described as covered in crystals in the first game, its appearance in the anime F-Zero: Falcon Densetsu and the games based on this media shows ice and snow as the dominant features of this venue.
Lava worlds can be seen occasionally in science fiction. In Star Wars, one such planet is Mustafar, with its heat caused by tidal forces from nearby gas giants. Mustafar scenes take place in Star Wars: Episode III – Revenge of the Sith.
A lava world called Solar is also featured in Star Fox 64.
A venue named Fire Field appears in the F-Zero franchise, where it is the last track of the King League in the first game. It is also notable for being one of the few venues to appear in every game of the franchise.
Excalbia is a planet with a mostly molten lava surface, featured in Star Trek: The Original Series (episode The Savage Curtain). Silicon-based beings native to the planet (Excalbians) create a habitable earthlike area on the surface. There, Kirk and Spock, along with replicas of Abraham Lincoln and Surak are pitted against replicas of four historical figures considered "evil" by the Federation. Ostensibly this is so that they can gain an understanding of the concept of "good vs. evil"
Other desert planets have been used as story motifs in fictional works:
|Abydos||Stargate and later in the TV series Stargate SG-1||1994||Film|
|Altair IV||Forbidden Planet||1956||Film|||
|Anarres||The Dispossessed by Ursula K. Le Guin||1974||Novel||Not strictly a desert planet; has oceans and is predominantly steppe|
|Arrakis (aka Dune)||Dune by Frank Herbert, and subsequent works in the Dune universe||1965||Novel||Homeworld of the Fremen and source of the valuable spice melange|||
|Athas||Dark Sun setting for Dungeons & Dragons||1991||Role-playing game|
|Bara Magna||Bionicle||2009||Toy line||Large utopian planet struck by a cataclysm 100,000 years previous|
|Barrayar||Shards of Honor by Lois McMaster Bujold and subsequent works in the Vorkosigan Saga||1986||Novel||Lead planet of the Barrayaran Empire. Originally colonized by humans 400 years prior to the start of Shards of Honor, Barrayar is then cut off after a wormhole collapse and regresses to a feudal system. After fighting off human invaders centuries in the future, Barrayar becomes a space-faring empire but remains backwards in several respects.|||
|Beachworld||"Beachworld" by Stephen King||1985||Short story|
|Byss||Star Wars: Dark Empire||1991–1992||Comic book|
|Canopus III||Star Trek: The Animated Series episode "The Eye of the Beholder"||1974||Animated TV series|
|Cardassia IV||Star Trek: Deep Space Nine episode "The Homecoming"||1993||TV series|
|Ceti Alpha V||Star Trek: The Original Series episode "Space Seed", Star Trek II: The Wrath of Khan||1967, 1982||TV series, film||Became the home of dictator Khan Noonien Singh and his followers following the events of Space Seed. Became a desert planet six months later when neighbouring Ceti Alpha VI exploded, with the loss of nearly all life on Ceti Alpha V|
|Dorvan V||Star Trek: The Next Generation episode "Journey's End"||1994||TV series|
|Dozaria||Star Trek: Deep Space Nine episode "Indiscretion"||1995||TV series|
|Fire||Lexx season 3||1999||TV series||An afterlife planet for the souls of deceased people, who made unvirtuous choices when they were alive. The inhabitants build their cities high above the ground to avoid the deadly heat emanating from the planet's core.|
|Fyrine IV||Enemy Mine||1985||Film|
|Gamma X||Les Maîtres du temps||1982||Animated film|
|Geonosis||Star Wars: Episode II – Attack of the Clones||2002||Film||Formerly populated by Insectoid Geonosians, a key system in the Confederacy of Independent systems during the Clone Wars, the Specters found evidence that the Geonosians had been exterminated by the Galactic Empire. This was done in an effort to cover up the origins of the Death Star Plans.|
|Hellywood||Now and Then, Here and There||1999-2000||Anime series|
|Home||Worldwar||1994-2004||book series||The homeworld of the reptilian Race. The human designation is Tau Ceti II.|
|Jakku||Star Wars: The Force Awakens||2015||Film||It was the location of an Observatory run by the Galactic Empire to chart a safe route through the Unknown Regions. Information provided by this facility and other Imperial sources led the First Order to the original location of Starkiller Base.|||
|Katina||Star Fox 64 and Star Fox Assault||
Video game || ||
|Kerona||Space Quest: The Sarien Encounter||1986||Computer game|
|Kharak||Homeworld||1999||Real-time strategy video game||Planet bombed by the Taiidan Empire|
|Khoros||Ben 10||2005–2008||Animated TV series||Homeworld of the Tetramands, species to which the alien Fourarms belongs|
|Klendathu||Starship Troopers by Robert A. Heinlein, and subsequent works||1959||Novel||Homeworld of the Arachnids|
|Kolarus III||Star Trek Nemesis||2002||Film|
|Korhal||StarCraft and subsequent games in the StarCraft franchise||1998||Real-time strategy video game||Once-lush throne world of the Terran Dominion|
|Korriban||Star Wars: Knights of the Old Republic||2003||Computer game||Birthplace of the Sith Order. Later appears in Star Wars: The Clone Wars under the name Moraband.|
|M6-117||Pitch Black||2000||Film||Gas giant's moon|
|Marak's World||Hammerfall (and later 2004's Forge of Heaven) by C. J. Cherryh||2001||Novel|
|Motavia||Phantasy Star||1987||Video game||Terraformed into a forest planet in Phantasy Star II|
|Ocampa||Star Trek: Voyager||1994–1997||TV series||Devastated homeworld of Kes and the Ocampa|
|Osiris IV||Futurama episode "A Pharaoh to Remember"||2002||Animated TV series|
|Perdide||Les Maîtres du temps||1982||Animated film|
|Resurgam||Revelation Space by Alastair Reynolds||2000||Novel|
|Rock Star||Kirby 64: The Crystal Shards||2000||Video Game|
|Salt||Salt by Adam Roberts||2000||Novel|
|Sand Ocean||F-Zero||1991||Video Game||Featured in the first game as the third track of the Knight League|
|Socorro||Star Wars: The Roleplaying Game adventure The Black Sands of Socorro||1997||Role-playing game|
|Starbuck||Galactica 1980 episode "The Return of Starbuck"||1980||TV series|
|Tallarn and other planets||Warhammer 40,000 universe||Miniature wargame|
|Tatooine||Star Wars, Return of the Jedi, all the Star Wars prequel trilogy films and Star Wars: The Rise of Skywalker||1977 - 2019||Film||Gangster-controlled desert planet home to Jabba the Hutt and Anakin and Luke Skywalker, despite neither of the three being born there. Also location of Obi-Wan Kenobi's exile.|
|Titania||Star Fox 64 for Nintendo 64||1997||Video game|
|Tophet||Roughnecks: Starship Troopers Chronicles||1999||Animated TV series|
|Torga IV||Star Trek: Deep Space Nine episode "The Ship"||1996||TV series|
|Toroth||Star Trek: Enterprise episode "Desert Crossing"||2002||TV series|
|Trisol||Futurama episode "My Three Suns"||1999||Animated TV series|
|Tyree||Star Trek: Deep Space Nine episodes "Image in the Sand" and "Shadows and Symbols"||1998||TV series|
|Unnamed planet||Snare by Katharine Kerr||2003||Novel|
|Unnamed planet||Star Trek episode "Arena"||1967||TV series|
|Vega||Spaceballs||1987||Film||Home planet to Schwartz-master Yogurt|
|Vulcan||Star Trek: The Original Series and subsequent works in the Star Trek universe||1966||TV series||Homeworld of the Vulcan race||
Yulin (planet in Sentinels of the galaxy) one of the 64 warrior planets
Contains planets not found in the preceding list
These planets are identical or nearly identical to Earth physically, but have a history that differs to some degree from that of our Earth.
Some writers, scientists and artists have speculated about artificial worlds or planet-equivalents; these planets include:
Some invented planets have physically impossible shapes, and may be regarded as fantasy worlds:
These planets are not so much carefully constructed worlds as they are humorous backgrounds or gag references in various comedy shows and games: