|
Fictional Planets Of The Solar System
Fictional planets of the Solar System have been depicted since the 1700s—often but not always corresponding to List of hypothetical Solar System objects, hypothetical planets that have at one point or another been seriously proposed by real-world astronomers, though commonly persisting in fiction long after the underlying scientific theories have been refuted. Vulcan (hypothetical planet), Vulcan was a planet hypothesized to exist inside the orbit of Mercury (planet), Mercury between 1859 and 1915 to explain Perihelion precession of Mercury, anomalies in Mercury's orbit until Albert Einstein, Einstein's theory of general relativity resolved the matter; it continued to appear in fiction as late as the 1960s. Counter-Earth—a planet diametrically opposite Earth in its orbit around the Sun—was originally proposed by the Ancient Greece, ancient Greek philosopher Philolaus in the fifth century BCE (albeit in a pre-Heliocentrism, heliocentric framework), and has appeared in fiction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, frost, larger polar regions of permafrost and ice caps (with seasonal snow), but no liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. It is half as wide as Earth or twice the Moon, with a diameter of , and has a surface area the size of all the dry land of Earth. Fine dust is prevalent across the surface and the atmosphere, being picked up and spread at the low Martian gravity even by the weak wind of the tenuous atmosphere. The terrain of Mars roughly follows a north-south ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dwarf Planet
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the eight classical planets of the Solar System. The prototypical dwarf planet is Pluto, which for decades was regarded as a planet before the "dwarf" concept was adopted in 2006. Dwarf planets are capable of being geologically active, an expectation that was borne out in 2015 by the ''Dawn (spacecraft), Dawn'' mission to and the ''New Horizons'' mission to Pluto. planetary geology, Planetary geologists are therefore particularly interested in them. Astronomers are in general agreement that at least the List of possible dwarf planets#Likeliest dwarf planets, nine largest candidates are dwarf planets – in rough order of diameter, , , , , , , , , and . A considerable uncertainty remains over the tenth largest candidate , which may thus be co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by the most restrictive definition of the term: the terrestrial planets Mercury (planet), Mercury, Venus, Earth, and Mars, and the giant planets Jupiter, Saturn, Uranus, and Neptune. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion (astrophysics), accretion. The word ''planet'' comes from the Greek () . In Classical antiquity, antiquity, this word referred to the Sun, Moon, and five points of light visible to the naked eye that moved across the background of the stars—namely, Me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reclassification Of Pluto
The International Astronomical Union (IAU) adopted in August 2006 the definition made by Uruguayan astronomers Julio Ángel Fernández and Gonzalo Tancredi that stated, that in the Solar System, a ''planet'' is a celestial body that: # is in orbit around the Sun, # has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and # has " cleared the neighbourhood" around its orbit. A non-satellite body fulfilling only the first two of these criteria (such as Pluto, which had hitherto been considered a planet) is classified as a ''dwarf planet''. According to the IAU, "planets and dwarf planets are two distinct classes of objects" – in other words, "dwarf planets" are not planets. A non-satellite body fulfilling only the first criterion is termed a ''small Solar System body'' (SSSB). An alternate proposal included dwarf planets as a subcategory of planets, but IAU members voted against this proposal. The decision was a controversial one, and has drawn both suppo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discovery Of Pluto
Following the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began in the mid-19th century and continued at the start of the 20th with Percival Lowell's quest for Planet X. Lowell proposed the Planet Nine, Planet X hypothesis to explain Discovery of Neptune#Irregularities in Uranus' orbit, apparent discrepancies in the orbits of the giant planets, particularly Uranus and Neptune, speculating that the gravity of a large unseen ninth planet could have gravitational perturbation, perturbed Uranus enough to account for the irregularities. Clyde Tombaugh's discovery of Pluto in 1930 appeared to validate Lowell's hypothesis, and Pluto was officially named the ninth planet. In 1978, Pluto was conclusively determined to be too small for its gravity to affect the giant planets, resulting in a brief search for a tenth planet. The search was largely abandoned in the early 1990s, when a study of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume by a small margin, but is less massive than Eris (dwarf planet), Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Pluto has roughly one-sixth the mass of the Moon and one-third its volume. Originally considered a planet, its classification was changed when astronomers adopted a new definition of planet, definition of ''planet''. Pluto has a moderately Orbital eccentricity, eccentric and Inclination, inclined orbit, ranging from from the Sun. Light from the Sun takes 5.5 hours to reach Pluto at its orbital distance of . Pluto's eccentric orbit periodically brings it closer to the Sun than Neptune, but a stabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neptune
Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth. Compared to Uranus, its neighbouring ice giant, Neptune is slightly smaller, but more massive and denser. Being composed primarily of gases and liquids, it has no well-defined solid surface. Neptune orbits the Sun once every 164.8 julian year (astronomy), years at an orbital distance of . It is named after Neptune (mythology), the Roman god of the sea and has the astronomical symbol representing Trident of Poseidon, Neptune's trident. Neptune is not visible to the unaided eye and is the only planet in the Solar System that was not initially observed by direct empirical observation. Rather, unexpected changes in the orbit of Uranus led Alexis Bouvard to hypothesise that its orbit was subject to gravitational Pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Bomb
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear explosion. Both bomb types release large quantities of energy from relatively small amounts of matter. Nuclear bombs have had yields between 10 tons (the W54) and 50 megatons for the Tsar Bomba (see TNT equivalent). Yields in the low kilotons can devastate cities. A thermonuclear weapon weighing as little as can release energy equal to more than 1.2 megatons of TNT (5.0 PJ). Apart from the blast, effects of nuclear weapons include firestorms, extreme heat and ionizing radiation, radioactive nuclear fallout, an electromagnetic pulse, and a radar blackout. The first nuclear weapons were developed by the Allied Manhattan Project during World War II. Their production continues to require a large scientific and industrial complex, primari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth Analog
An Earth analog, also called an Earth twin or second Earth, is a Exoplanet, planet or Exomoon, 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. The possibility is of particular interest to Astrobiology, astrobiologists and astronomers under reasoning that the more similar a planet is to Earth, the more likely it is to be capable of sustaining complex extraterrestrial life. As such, it has long been speculated and the subject expressed in science, philosophy, science fiction and popular culture. Advocates of space colonization and space and survival have long sought an Earth analog for settlement. In the far future, humans might artificially produce an Earth analog by terraforming. Before the scientific search for and study of exoplanet, extrasolar planets, the possibility was argued through philosophy and science fiction. Philosophers have suggested that the size of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulp Era Of Science Fiction
In the history of science fiction, the pulp era (occasionally pulp age) is a period subject to various definitions. It is commonly held to have begun in 1926, the year the first science fiction magazine—Hugo Gernsback's ''Amazing Stories''—was launched. The end point is usually placed in the 1950s, when the pulp magazines ceased publication. Various largely similar definitions exist that differ by a few years in either direction at the beginning or end of the period, though there are some outliers—by the broadest definition the era began in 1896 with the first (albeit genre-nonspecific) pulp magazine '' Argosy'', and by the narrowest it ended in 1937 with the onset of the Golden Age of Science Fiction. Background The first pulp magazine appeared in 1896 when Frank Munsey changed the format of '' Argosy'' and started printing it on pulp paper. ''Argosy'' and the magazines that followed in its wake carried general fiction, including science fiction; the first science ficti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science Fiction
Science fiction (often shortened to sci-fi or abbreviated SF) is a genre of speculative fiction that deals with imaginative and futuristic concepts. These concepts may include information technology and robotics, biological manipulations, space exploration, time travel, Parallel universes in fiction, parallel universes, and extraterrestrials in fiction, extraterrestrial life. The genre often explores human responses to the consequences of projected or imagined scientific advances. Science fiction is related to fantasy (together abbreviated wikt:SF&F, SF&F), Horror fiction, horror, and superhero fiction, and it contains many #Subgenres, subgenres. The genre's precise Definitions of science fiction, definition has long been disputed among authors, critics, scholars, and readers. Major subgenres include hard science fiction, ''hard'' science fiction, which emphasizes scientific accuracy, and soft science fiction, ''soft'' science fiction, which focuses on social sciences. Other no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
