Floating cities and islands in fiction


In speculative fiction, floating cities and islands are a common trope, which range 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. While very large floating structures have been constructed or proposed in real life, aerial cities and islands remain in the realm of fiction.

Seaborne cities and islands

Seaborne floating islands have been found in literature since Homer's Odyssey, written near the end of the 8th century BC, described the island of Aeolia. They reappear in Pliny the Elder's Natural History of the 1st century AD.
Richard Head‘s 1673 novel The Floating Island describes a fictional island named Scotia Moria. In the DC comics story of Wonder Woman, Themyscira is a group of floating islands. In Jules Verne‘s Propeller Island, the characters are on an artificial floating island that is actually a huge ship. In Yann Martel‘s novel Life of Pi, there is a floating island.

Airborne cities and islands

Earth

In the novel Gulliver's Travels by Jonathan Swift, it depicted Laputa, an island city that floated in the sky. Laputa purportedly levitated through use of artificial magnetism. It was primarily a fictional device that was intended to satirize far-fetched pseudo-scientific proposals.
During the 1920s, science fiction author Hugo Gernsback speculated 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 architects Buckminster Fuller and Shoji Sadao proposed the construction of a thermal airship, which they called Cloud Nine. This megastructure would be a geodesic sphere that, 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.
The "Triton City" was the work of the Triton Foundation whose principal members were Buckminster Fuller and Shoji Sadao, was commissioned by HUD, a federal agency, by its director, Charles Haar, a Harvard professor, to design a floating city to provide housing in urban areas located near the ocean. A tetrahedron shaped module holding 5,000 inhabitants was designed and a comprehensive engineering report was submitted together with a large model which is on display in the lobby of the Lyndon B. Johnson Center in Austin, Texas.

Venus

A design similar to Fuller's Cloud Nine might permit habitation in the upper atmosphere of Venus, where at ground level the temperature is too high and the atmospheric pressure too great. As proposed by Geoffrey A. Landis, the easiest planet to place floating cities at this point would appear to be Venus. Because the thick carbon dioxide atmosphere is 50% denser than air, breathable air is a lifting gas in the dense Venerean atmosphere, with over 60% of the lifting power that helium has on Earth. In effect, a balloon full of human-breathable air would sustain itself and extra weight in midair. This means that any large structure filled with air would float on the carbon dioxide, with the air's natural buoyancy counteracting the weight of the structure itself.
At an altitude of 50 km above the Venerean surface, the environment is the "most Earthlike in the solar system", with a pressure of approximately 1 bar and temperatures in the 0°C-50°C range. Because there is not a significant pressure difference between the inside and the outside of the breathable-air balloon, any rips or tears would cause gases to diffuse at normal atmospheric mixing rates, giving time to repair any such damage. In addition, humans would not require pressurized suits when outside, merely air to breathe and a protection from the acidic rain.
Since such colonies would be viable in current Venerean conditions, this allows a dynamic approach to colonization instead of requiring extensive terraforming measures in advance. The main challenge would be using a substance resistant to sulfuric acid to serve as the structure's outer layer; ceramics or metal sulfates could possibly serve in this role.

Other planets

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 three gas giants, as the gas giants lack solid surfaces. Jupiter is not promising for habitation due to its high gravity, escape velocity and radiation, but the solar system's other gas giants may be more practical. In 1978, the British Interplanetary Society's Project Daedalus envisioned floating factories in the atmospheres of Jupiter refining helium-3 to produce fuel for an interstellar probe. Michael McCollum notes that the "surface" gravity of Saturn is very close to that of Earth, and in his novel The Clouds of Saturn, he envisioned cities floating in the Saturnian atmosphere, where the buoyancy is provided by envelopes of hydrogen heated by fusion reactors. Uranus and Neptune also have upper atmosphere gravities comparable to Earth's, and even lower escape velocities than Saturn. Cecelia Holland populated Jupiter, Saturn and Uranus with mutant humans, the Styth, in floating cities in her only SF novel, Floating Worlds.

Fictional examples

Literature