Extraterrestrial life, alien life, or colloquially simply aliens is life which does not originate from Earth. No extraterrestrial life has yet been conclusively detected. Such life might range from simple forms such as prokaryotes to intelligent beings, possibly bringing forth civilizations that might be far more advanced than humanity. The Drake equation speculates about the existence of sapient life elsewhere in the universe. The science of extraterrestrial life is known as astrobiology.
Known Space is the fictional setting of about a dozen science fiction novels and several collections of short stories by American writer Larry Niven. It has also become a shared universe in the spin-off Man-Kzin Wars anthologies. The Internet Speculative Fiction Database (ISFDB) catalogs all works set in the fictional universe that includes Known Space under the series name Tales of Known Space, which was the title of a 1975 collection of Niven's short stories. The first-published work in the series, which was Niven's first published piece, was "The Coldest Place", in the December 1964 issue of If magazine, edited by Frederik Pohl. This was the first-published work in the 1975 collection.
Space colonization is the use of outer space or celestial bodies other than Earth for permanent habitation or as extraterrestrial territory.
Terraforming or terraformation ("Earth-shaping") is the hypothetical process of deliberately modifying the atmosphere, temperature, surface topography or ecology of a planet, moon, or other body to be similar to the environment of Earth to make it habitable for humans to live on.
The Mars trilogy is a series of science fiction novels by Kim Stanley Robinson that chronicles the settlement and terraforming of the planet Mars through the personal and detailed viewpoints of a wide variety of characters spanning almost two centuries. Ultimately more utopian than dystopian, the story focuses on egalitarian, sociological, and scientific advances made on Mars, while Earth suffers from overpopulation and ecological disaster.
The Childe Cycle is an unfinished series of science fiction novels by Canadian writer Gordon R. Dickson. The name Childe Cycle is an allusion to "Childe Roland to the Dark Tower Came", a poem by Robert Browning, which provided inspiration for elements in the work. The series is sometimes referred to as the Dorsai series, after the Dorsai people who are central to it. The related short stories and novellas all center on the Dorsai, primarily members of the Graeme and Morgan families.
The Songs of Distant Earth is a 1986 science fiction novel by British writer Arthur C. Clarke, based upon his 1958 short story of the same title. Of all of his novels, Clarke stated that this was his favourite. Prior to the publishing of the novel, Clarke also wrote a short step outline with the same title, published in Omni magazine and anthologised in The Sentinel in 1983.
Exiles on Asperus is a collection of three science fiction novelettes/novellas by British writer John Wyndham, writing as John Beynon, published in 1979 after his death by Coronet Books.
Lucky Starr and the Oceans of Venus is the third novel in the Lucky Starr series, six juvenile science fiction novels by Isaac Asimov that originally appeared under the pseudonym Paul French. The novel was first published by Doubleday & Company in 1954. Since 1972, reprints have included a foreword by Asimov explaining that advancing knowledge of conditions on Venus have rendered the novel's descriptions of that world inaccurate.
The planet Venus has been used as a setting in fiction since before the 19th century. Its opaque cloud cover gave science fiction writers free rein to speculate on conditions at its surface—a "cosmic Rorschach test", in the words of science fiction author Stephen L. Gillett. The planet was often depicted as warmer than Earth but still habitable by humans. Depictions of Venus as a lush, verdant paradise, an oceanic planet, or fetid swampland, often inhabited by dinosaur-like beasts or other monsters, became common in early pulp science fiction, particularly between the 1930s and 1950s. Some other stories portrayed it as a desert, or invented more exotic settings. The absence of a common vision resulted in Venus not developing a coherent fictional mythology, in contrast to the image of Mars in fiction.
Inconstant Moon is a science fiction short story collection by American author Larry Niven that was published in 1973. "Inconstant Moon" is also a 1971 short story that is included in the collection. The title refers to "O, swear not by the moon, th' inconstant moon", a quote from the balcony scene in William Shakespeare's Romeo and Juliet. The collection was assembled from the US collections The Shape of Space and All the Myriad Ways.
The colonization of Venus has been a subject of many works of science fiction since before the dawn of spaceflight, and is still discussed from both a fictional and a scientific standpoint. However, with the discovery of Venus's extremely hostile surface environment, attention has largely shifted towards the colonization of the Moon and Mars instead, with proposals for Venus focused on habitats floating in the upper-middle atmosphere and on terraforming.
In science 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.
Farewell, Fantastic Venus is a 1968 American science fiction anthology edited by Brian Aldiss and Harry Harrison. An abridged version was published in the same year under the title All About Venus. It was first published as a direct response to the information returned from the first space probes sent to Venus, especially the first atmospheric probe to return data, Venera 4. The first data was not returned from the surface until Venera 7 successfully landed in 1970.
Saturn has made appearances in fiction since the 1752 novel Micromégas by Voltaire. In the earliest depictions, it was portrayed as having a solid surface rather than its actual gaseous composition. In many of these works, the planet is inhabited by aliens that are usually portrayed as being more advanced than humans. In modern science fiction, the Saturnian atmosphere sometimes hosts floating settlements. The planet is occasionally visited by humans and its rings are sometimes mined for resources.
The terraforming of Mars or the terraformation of Mars is a hypothetical procedure that would consist of a planetary engineering project or concurrent projects aspiring to transform Mars from a planet hostile to terrestrial life to one that could sustainably host humans and other lifeforms free of protection or mediation. The process would involve the modification of the planet's extant climate, atmosphere, and surface through a variety of resource-intensive initiatives, as well as the installation of a novel ecological system or systems.
The terraforming of Venus or the terraformation of Venus is the hypothetical process of engineering the global environment of the planet Venus in order to make it suitable for human habitation. Adjustments to the existing environment of Venus to support human life would require at least three major changes to the planet's atmosphere:
- Reducing Venus's surface temperature of 737 K
- Eliminating most of the planet's dense 9.2 MPa (91 atm) carbon dioxide and sulfur dioxide atmosphere via removal or conversion to some other form
- The addition of breathable oxygen to the atmosphere.
The Stars Are Ours! is a 1954 science fiction novel by American writer Andre Norton. It describes the first interstellar voyage, undertaken to escape the tyranny that rules the Earth. Norton wrote a sequel, Star Born, which was published in 1957.
The Sky People is an alternate history science fiction novel by American writer S. M. Stirling. It was first published by Tor Books in hardcover in November 2006, with a book club edition co-published with the Science Fiction Book Club following in December of the same year. Tor issued paperback, ebook, and trade paperback editions in October 2007, April 2010, and May 2010 respectively. Audiobook editions were published by Tantor Media in January 2007.
An Earth analog, also called an Earth analogue, Earth twin, or second Earth, is a planet or moon with environmental conditions similar to those found on Earth. The term Earth-like planet is also used, but this term may refer to any terrestrial planet.