Floating cities and islands in fiction

Inscience fictionandfantasy,floating cities and islandsare a commontrope, ranging from cities and islands that float on water to ones that float in the atmosphere of a planet by purported scientific technologies or by magical means. Whilevery large floating structureshave been constructed or proposed in real life, aerial cities and islands remain in the realm of fiction.
Seabornefloating islandshave been found in literature sinceHomer'sOdyssey, written near the end of the 8th century BCE, described the island ofAeolia.They reappear inPliny the Elder'sNatural Historyof the 1st century CE.
Richard Head‘s 1673 novelThe Floating Islanddescribes a fictional island named Scotia Moria. InThe Voyages of Doctor Dolittle, the characters sail to a floating island, which later becomes fixed in place. In the DC comics story ofWonder Woman, Themyscira is a group of floating islands. In Jules Verne‘sPropeller Island, the characters are on an artificial floating island that is actually a huge ship. In Yann Martel‘s novelLife of Pi, there is a floating island.
In the treatiseDe Grandine et Tonitruis("On Hail and Thunder", 815),CarolingianbishopAgobardofLyondescribesMagonia,a cloud realm populated by felonious aerial sailors.
In thenovelGulliver's Travels(1726) byJonathan Swift, the island city ofLaputawas revealed to be floating in the sky. Laputa purportedly levitated through use of artificialmagnetism. It was primarily afictional devicethat was intended tosatirizefar-fetchedpseudo-scientificproposals:
During the 1920s, science fiction authorHugo Gernsbackspeculated about floating cities of the future, suggesting that 10,000 years hence "the city the size of New York will float several miles above the surface of the earth, where the air is cleaner and purer and free from disease carrying bacteria." To stay in the air, "four gigantic generators will shoot earthward electric rays which by reaction with the earth produce the force to keep the city aloft."
In 1960, the architectsBuckminster FullerandShoji Sadaoproposed the construction of a 1-mile-diameter (1.6 km)thermal airship, which they calledCloud Nine. Thismegastructurewould be ageodesic spherethat, once it was sufficiently heated by sunlight, would become airborne.Fuller and Sadao envisioned that Cloud Nine would float freely in the Earth's atmosphere, giving residents and passengers a migratory lifestyle. They believed that it might be a partial solution to the depletion of non-renewable resources.
A team including Buckminster Fuller andShoji Sadaowas commissioned byUnited States Department of Housing and Urban Developmentto design the Triton City, a floating city intended to provide housing nearTokyoorBaltimore. The proposal called fortetrahedron–shaped modules supporting large housing blocks of 5,000 inhabitants each, and which would be anchored to the ground. A large model of the habitat is on display in the lobby of theJohnson Presidential LibraryinAustin, Texas.
InIsaac Asimov's story "Shah Guido G.", the hereditarySecretary-General of the United Nations("Sekjen") is a tyrant who rules theEarthfrom a flying island calledAtlantis.
A design similar to Fuller'sCloud Ninemight permit habitation in the upper atmosphere ofVenus, where at ground level the temperature is too high and theatmospheric pressuretoo great. As scientifically and fictionally described byGeoffrey A. Landis, the easiest planet (other than Earth) to place floating cities at this point would appear to beVenus.Becausethe thick carbon dioxide atmosphereis 50% denser thanEarth's atmosphere, breathable air with a composition similar to the latter is a lifting gas in the dense Venerean atmosphere, with over 60% of the lifting power thatheliumhas on Earth.At an altitude of 50 km above the Venerean surface, the environment is the "most Earthlike in the solar system", according to Landis,with a pressure of approximately 1 bar and temperatures ranging between 0–50 °C (32–122 °F).
In addition to Venus, floating cities have been proposed in science fiction on several other planets. For example, floating cities might also permit settlement of the outer threegas giants, as the gas giants lack solid surfaces.Jupiteris not promising for habitation due to its highgravity,escape velocityandradiation, but theSolar System's other gas giants (Saturn,Uranus, andNeptune) may be more practical. In 1978, theBritish Interplanetary Society'sProject Daedalusenvisioned floating factories in the atmospheres of Jupiter refininghelium-3to produce fuel for aninterstellar probe.Michael McCollumnotes that the "surface" gravity of Saturn (that is, at the visible cloud layer, where the atmospheric pressure is about the same as Earth's) is very close to that of Earth, and in his novelThe Clouds of Saturn, he envisioned cities floating in the Saturnian atmosphere, where the buoyancy is provided by envelopes ofhydrogenheated byfusion reactors. Uranus and Neptune also have upper atmosphere gravities comparable to Earth's, and even lower escape velocities than Saturn.Cecelia Hollandpopulated Jupiter, Saturn and Uranus with mutant humans, the Styth, in floating cities in her only SF novel,Floating Worlds(1975).Donald Moffitt's novelJovian(2003) features floating cities forever floating in the Jovian atmosphere, a worthwhile enterprise due to their ability to extract useful gases. The book concentrates on the cultural differences (and political tensions) developing between "Jovian" humans and Earthbound ones.