In the history of astronomy, a handful of Solar System bodies other than Jupiter have been counted as the fifth planet from the Sun. Various hypotheses have also postulated the former existence of a fifth planet, now destroyed, to explain various characteristics of the inner Solar System.
There are three main ideas regarding hypothetical planets between Mars and Jupiter.
During the early 19th century, as asteroids were discovered, they were formerly considered planets. Jupiter became the sixth planet with the discovery of Ceres in 1801. Soon, three more asteroids, Pallas (1802), Juno (1804), and Vesta (1807) were discovered. They were counted as separate planets, despite the fact that they share a single orbital spacing given by Titius–Bode law. Between 1845 and 1851, eleven additional asteroids were discovered and Jupiter had become the twentieth planet. At this point, astronomers began to classify asteroids as minor planets. [1] Following the reclassification of the asteroids in their own group, Jupiter became the fifth planet once again. Following the International Astronomical Union's (IAU) redefinition of the term planet in August 2006, Ceres is now considered a dwarf planet. [2]
The disruption hypothesis suggests that a planet which was positioned between Mars and Jupiter was destroyed, creating the asteroid belt between these planets. First proposed by astronomer Heinrich Wilhelm Matthias Olbers, scientists in the 20th century dubbed this hypothetical planet "Phaeton". Astronomers proposed various properties of Phaeton, including masses ranging from 1–8 ML and an icy composition. However, the hypothesis faced criticisms due to difficulties in adequately explaining the mechanisms behind planetary breakup. [3] The Phaeton hypothesis was eventually superseded by the accretion model, as the observed properties of the asteroid belt did not fit an origin from a single, disrupted planet. [4]
Based on simulations, NASA space scientists John Chambers and Jack J. Lissauer have proposed the existence of a planet between Mars and the asteroid belt, going in a successively eccentric and unstable orbit, 4 billion years ago. They connect this planet, which they name Planet V, and its disappearance with the Late Heavy Bombardment episode of the Hadean era. [5] [6] Chambers and Lissauer also claim this Planet V most probably ended up crashing into the Sun. Unlike the disruption hypothesis's fifth planet, "Planet V" is not credited with creating the asteroid belt.
A hypothetical former fifth planet that has since been destroyed has been referenced in fiction since at least the late 1800s. [7] [8] In science fiction, the planet is often called "Bodia" after Johann Elert Bode. [8] [9] By the pulp era of science fiction, Bodia was a recurring theme. In these stories it is typically similar to Earth and inhabited by humans, often advanced humans and occasionally the ancestors of humans on Earth. [10] [9] [11] [12] Following the invention of the atomic bomb in 1945, stories of this planetary destruction became increasingly common, encouraged by the advent of a plausible-seeming means of disintegration. [13] Several works of the 1950s used the idea to warn of the dangers of nuclear weapons. [7] [8] [14] The concept has since largely been relegated to deliberately retro works. [15]
The "science" in science-fiction of the Gernsback period was not wholly borrowed from the outside world. Some concepts were created on a mythical level. [...] Particularly interesting is the establishment of "Bodia" (according to one cosmology of the day, a former fifth planet whose destruction formed the asteroids) as the ultimate origin of mankind and possessor of a supercivilization.
Bode's Fifth Planet, "Bodia." (A hypothetical planet between Mars and Jupiter that broke up to form the asteroid belt. It is usually fictionally considered as Earth-like, with a human population.)
An asteroid is a minor planet—an object that is neither a true planet nor an identified comet— that orbits within the inner Solar System. They are rocky, metallic, or icy bodies with no atmosphere, classified as C-type (carbonaceous), M-type (metallic), or S-type (silicaceous). The size and shape of asteroids vary significantly, ranging from small rubble piles under a kilometer across and larger than meteoroids, to Ceres, a dwarf planet almost 1000 km in diameter. A body is classified as a comet, not an asteroid, if it shows a coma (tail) when warmed by solar radiation, although recent observations suggest a continuum between these types of bodies.
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids or minor planets. The identified objects are of many sizes, but much smaller than planets, and, on average, are about one million kilometers apart. This asteroid belt is also called the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System.
The Counter-Earth is a hypothetical body of the Solar System that orbits on the other side of the Solar System from Earth. A Counter-Earth or Antichthon was hypothesized by the pre-Socratic Greek philosopher Philolaus to support his non-geocentric cosmology, in which all objects in the universe revolve around a "Central Fire".
Planet V is a hypothetical fifth terrestrial planet posited by NASA scientists John Chambers and Jack J. Lissauer to have once existed between Mars and the asteroid belt. In their hypothesis the Late Heavy Bombardment of the Hadean era began after perturbations from the other terrestrial planets caused Planet V's orbit to cross into the asteroid belt. Chambers and Lissauer presented the results of initial tests of this hypothesis during the 33rd Lunar and Planetary Science Conference, held from March 11 through 15, 2002.
Jupiter, the largest planet in the Solar System, has appeared in works of fiction across several centuries. The way the planet has been depicted has evolved as more has become known about its composition; it was initially portrayed as being entirely solid, later as having a high-pressure atmosphere with a solid surface underneath, and finally as being entirely gaseous. It was a popular setting during the pulp era of science fiction. Life on the planet has variously been depicted as identical to humans, larger versions of humans, and non-human. Non-human life on Jupiter has been portrayed as primitive in some works and more advanced than humans in others.
Pluto has appeared in fiction as a setting since shortly after its 1930 discovery, albeit infrequently. It was initially comparatively popular as it was newly discovered and thought to be the outermost object of the Solar System and made more fictional appearances than either Uranus or Neptune, though still far fewer than other planets. Alien life, sometimes intelligent life and occasionally an entire ecosphere, is a common motif in fictional depictions of Pluto. Human settlement appears only sporadically, but it is often either the starting or finishing point for a tour of the Solar System. It has variously been depicted as an originally extrasolar planet, the remnants of a destroyed planet, or entirely artificial. Its moon Charon has also appeared in a handful of works.
Asteroids have appeared in fiction since at least the late 1800s, the first one—Ceres—having been discovered in 1801. They were initially only used infrequently as writers preferred the planets as settings. The once-popular Phaëton hypothesis, which states that the asteroid belt consists of the remnants of the former fifth planet that existed in an orbit between Mars and Jupiter before somehow being destroyed, has been a recurring theme with various explanations for the planet's destruction proposed. This hypothetical former planet is in science fiction often called "Bodia" in reference to Johann Elert Bode, for whom the since-discredited Titius–Bode law that predicts the planet's existence is named.
Neptune has appeared in fiction since shortly after its 1846 discovery, albeit infrequently. It initially made appearances indirectly—e.g. through its inhabitants—rather than as a setting. The earliest stories set on Neptune itself portrayed it as a rocky planet rather than as having its actual gaseous composition; later works rectified this error. Extraterrestrial life on Neptune is uncommon in fiction, though the exceptions have ranged from humanoids to gaseous lifeforms. Neptune's largest moon Triton has also appeared in fiction, especially in the late 20th century onwards.
Uranus has been used as a setting in works of fiction since shortly after its 1781 discovery, albeit infrequently. The earliest depictions portrayed it as having a solid surface, whereas later stories portrayed it more accurately as a gaseous planet. Its moons have also appeared in a handful of works. Both the planet and its moons have experienced a slight trend of increased representation in fiction over time.
Fictional planets of the Solar System have been depicted since the 1700s—often but not always corresponding to 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 was a planet hypothesized to exist inside the orbit of Mercury between 1859 and 1915 to explain anomalies in Mercury's orbit until 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 Greek philosopher Philolaus in the fifth century BCE, and has appeared in fiction since at least the late 1800s. It is sometimes depicted as very similar to Earth and other times very different, often used as a vehicle for satire, and frequently inhabited by counterparts of the people of Earth.
Phaeton was the hypothetical planet hypothesized by the Titius–Bode law to have existed between the orbits of Mars and Jupiter, the destruction of which supposedly led to the formation of the asteroid belt. The hypothetical planet was named for Phaethon, the son of the sun god Helios in Greek mythology, who attempted to drive his father's solar chariot for a day with disastrous results and was ultimately destroyed by Zeus.
Fifth planet may refer to:
Supernovae, extremely powerful explosions of stars, have been featured in works of fiction since at least the early 1900s. The idea that the Sun could explode in this manner has served as the basis for many stories about disaster striking Earth, though it is now recognized that this cannot actually happen. Recurring themes in these stories include anticipating the inevitable destruction while being helpless and evacuating the planet, sometimes with the assistance of helpful aliens. The destruction of Earth in this manner occasionally serves as backstory explaining why humanity has started colonizing the cosmos. Another recurring scenario is radiation from more distant supernovae threatening Earth. Besides humans, alien civilizations are also occasionally subject to the dangers of supernovae. Supernovae are induced intentionally in several works, typically for use as weapons but sometimes for more peaceful purposes, and naturally occurring supernovae are likewise exploited in some stories.
Comets have appeared in works of fiction since at least the 1830s. They primarily appear in science fiction as literal objects, but also make occasional symbolical appearances in other genres. In keeping with their traditional cultural associations as omens, they often threaten destruction to Earth. This commonly comes in the form of looming impact events, and occasionally through more novel means such as affecting Earth's atmosphere in different ways. In other stories, humans seek out and visit comets for purposes of research or resource extraction. Comets are inhabited by various forms of life ranging from microbes to vampires in different depictions, and are themselves living beings in some stories.
The following outline is provided as an overview of and topical guide to the Solar System:
The Sun has appeared as a setting in fiction at least since classical antiquity, but for a long time it received relatively sporadic attention. Many of the early depictions viewed it as an essentially Earth-like and thus potentially habitable body—a once-common belief about celestial objects in general known as the plurality of worlds—and depicted various kinds of solar inhabitants. As more became known about the Sun through advances in astronomy, in particular its temperature, solar inhabitants fell out of favour save for the occasional more exotic alien lifeforms. Instead, many stories focused on the eventual death of the Sun and the havoc it would wreak upon life on Earth. Before it was understood that the Sun is powered by nuclear fusion, the prevailing assumption among writers was that combustion was the source of its heat and light, and it was expected to run out of fuel relatively soon. Even after the true source of the Sun's energy was determined in the 1920s, the dimming or extinction of the Sun remained a recurring theme in disaster stories, with occasional attempts at averting disaster by reigniting the Sun. Another common way for the Sun to cause destruction is by exploding, and other mechanisms such as solar flares also appear on occasion.
Impact events have been a recurring theme in fiction since the 1800s.
Solar System belts are asteroid and comet belts that orbit the Sun in the Solar System in interplanetary space. The Solar System belts' size and placement are mostly a result of the Solar System having four giant planets: Jupiter, Saturn, Uranus and Neptune far from the sun. The giant planets must be in the correct place, not too close or too far from the sun for a system to have Solar System belts.