In astronomy, a double planet is a binary satellite system where both objects are planets, or planetary-mass objects, and whose joint barycenter is external to both planetary bodies.
Foundation's Edge (1982) is a science fiction novel by American writer Isaac Asimov, the fourth book in the Foundation Series. It was written more than thirty years after the stories of the original Foundation trilogy, due to years of pressure by fans and editors on Asimov to write another, and, according to Asimov himself, the amount of the payment offered by the publisher. It was his first novel to ever land on The New York Times best-seller list, after 262 books and 44 years of writing.
Foundation and Earth is a science fiction novel by American writer Isaac Asimov, the fifth novel of the Foundation series and chronologically the last in the series. It was published in 1986, four years after the first sequel to the Foundation trilogy, which is titled Foundation's Edge.
The Foundation series is a science fiction book series written by American author Isaac Asimov. First published as a series of short stories and novellas in 1942–50, and subsequently in three collections in 1951–53, for nearly thirty years the series was a trilogy: Foundation (1951); Foundation and Empire (1952); and Second Foundation (1953). It won the one-time Hugo Award for "Best All-Time Series" in 1966. Asimov later added new volumes, with two sequels: Foundation's Edge (1982) and Foundation and Earth (1986), and two prequels: Prelude to Foundation (1988) and Forward the Foundation (1993).
Nemesis is a hypothetical red dwarf or brown dwarf, originally postulated in 1984 to be orbiting the Sun at a distance of about 95,000 AU, somewhat beyond the Oort cloud, to explain a perceived cycle of mass extinctions in the geological record, which seem to occur more often at intervals of 26 million years. In a 2017 paper, Sarah Sadavoy and Steven Stahler argued that the Sun was probably part of a binary system at the time of its formation, leading them to suggest "there probably was a Nemesis, a long time ago". Such a star would have separated from this binary system over four billion years ago, meaning it could not be responsible for the more recent perceived cycle of mass extinctions.
Hari Seldon is a fictional character in the Foundation series of novels by Isaac Asimov. In his capacity as mathematics professor at Streeling University on the planet Trantor, Seldon develops psychohistory, an algorithmic science that allows him to predict the future in probabilistic terms. On the basis of his psychohistory he is able to predict the eventual fall of the Galactic Empire and to develop a means to shorten the millennia of chaos to follow.
Robots and Empire is a science fiction novel by the American author Isaac Asimov, published by Doubleday Books in 1985. It is part of Asimov's Robot series, which consists of many short stories and five novels.
Foundation's Triumph (1999) is a science fiction novel by American writer David Brin, set in Isaac Asimov's Foundation universe. It is the third book of the Second Foundation trilogy, which was written after Asimov's death by three authors, authorized by the Asimov estate. Brin synthesizes dozens of Foundation-Empire-Robots novels and short stories by Isaac Asimov, Roger MacBride Allen, and authorized others into a consistent framework. Foundation's Triumph includes an appendix chronology compiled by Attila Torkos.
The Galactic Empire is an interstellar empire featured in Isaac Asimov's Robot, Galactic Empire, and Foundation series. The Empire is spread across the Milky Way galaxy and consists of almost 25 million planets settled exclusively by humans. For over 12 millennia the seat of imperial authority was located on the ecumenopolis of Trantor, whose population exceeded 40 billion, until it was sacked in the year 12,328. The official symbol of the empire is the Spaceship-and-Sun. Cleon II was the last Emperor to hold significant authority. The fall of the empire, modelled on the fall of the Roman Empire, is the subject of many of Asimov's novels.
This is a bibliography of the books written or edited by Isaac Asimov, arranged alphabetically. Asimov was a prolific author, and he engaged in many collaborations with other authors. This list may not yet be complete. The total number of books listed here is over 500. Asimov died in 1992 at age 72; a small number of his books were published posthumously.
"Nightfall" is a 1941 science fiction short story by the American writer Isaac Asimov about the coming of darkness to the people of a planet ordinarily illuminated by sunlight at all times. It was adapted into a novel with Robert Silverberg in 1990. The short story has appeared in many anthologies and six collections of Asimov stories. In 1968, the Science Fiction Writers of America voted "Nightfall" the best science fiction short story written prior to the 1965 establishment of the Nebula Awards and included it in The Science Fiction Hall of Fame, Volume One, 1929–1964.
Gliese 876 is a red dwarf star 15.2 light-years away from Earth in the constellation of Aquarius. It is one of the closest known stars to the Sun confirmed to possess a planetary system with more than two planets, after GJ 1061, YZ Ceti, Tau Ceti, and Wolf 1061; as of 2018, four extrasolar planets have been found to orbit the star. The planetary system is also notable for the orbital properties of its planets. It is the only known system of orbital companions to exhibit a near-triple conjunction in the rare phenomenon of Laplace resonance. It is also the first extrasolar system around a normal star with measured coplanarity. While planets b and c are located in the system's habitable zone, they are giant planets believed to be analogous to Jupiter.
Gliese 581 is a red dwarf star of spectral type M3V which hosts a planetary system, 20.5 light-years away from Earth in the Libra constellation. Its estimated mass is about a third of that of the Sun, and it is the 101st closest known star system to the Sun. Gliese 581 is one of the oldest, least active M dwarfs known. Its low stellar activity improves the likelihood of its planets retaining significant atmospheres, and lessens the sterilizing impact of stellar flares.
OGLE-2005-BLG-390Lb is a super-Earth exoplanet orbiting OGLE-2005-BLG-390L, a star 21,500 ± 3,300 light-years from Earth near the center of the Milky Way, making it one of the most distant planets known. On January 25, 2006, Probing Lensing Anomalies NETwork/Robotic Telescope Network (PLANET/Robonet), Optical Gravitational Lensing Experiment (OGLE), and Microlensing Observations in Astrophysics (MOA) made a joint announcement of the discovery. The planet does not appear to meet conditions presumed necessary to support life.
Gliese 581b or Gl 581b is an exoplanet orbiting within the Gliese 581 system, located 20.5 light-years away from Earth in the Libra constellation. It is the first planet discovered of three confirmed in the system so far, and the second in order from the star.
Gliese 876 b is an exoplanet orbiting the red dwarf Gliese 876. It completes one orbit in approximately 61 days. Discovered in June 1998, Gliese 876 b was the first planet to be discovered orbiting a red dwarf.
Planets outside of the Solar System have appeared in fiction since at least the 1850s, long before the first real ones were discovered in the 1990s. Most of these fictional planets do not differ significantly from the Earth, and serve only as settings for the narrative. The majority host native lifeforms, sometimes with humans integrated into the ecosystems. Fictional planets that are not Earth-like vary in many different ways. They may have significantly stronger or weaker gravity on their surfaces, or have a particularly hot or cold climate. Both desert planets and ocean planets appear, as do planets with unusual chemical conditions. Various peculiar planetary shapes have been depicted, including flattened, cubic, and toroidal. Some fictional planets exist in in multiple-star systems where the orbital mechanics can lead to exotic day–night or seasonal cycles, while others do not orbit any star at all. More fancifully, planets are occasionally portrayed as having sentience, though this is less common than stars receiving the same treatment or a planet's lifeforms having a collective consciousness.
A Super-Earth is a type of exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term.
The Foundation universe is the future history of humanity's colonization of the galaxy, spanning nearly 25,000 years, created through the gradual fusion of the Robot, Galactic Empire, and Foundation book series written by American author Isaac Asimov.
In a writing career spanning 53 years (1939–1992), science fiction and popular science author Isaac Asimov (1920–1992) wrote and published 40 novels, 383 short stories, over 280 non-fiction books, and edited about 147 others.
