Interstellar planet

Interstellar planet

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A rogue planet is a planetary-mass object that has been ejected from its system and is no longer gravitationally bound to any star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

, brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...

 or other such object, and that therefore orbits the galaxy
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

 directly. Some astronomers have estimated that there may be twice as many Jupiter-sized rogue planets as there are stars.

Isolated planetary-mass objects which were not ejected, but have always been free-floating, are thought to have formed in a similar way to stars, and the IAU has proposed that those objects be called sub-brown dwarf
Sub-brown dwarf
A sub-brown dwarf is an astronomical object of planetary mass that is not orbiting a star and is not considered to be a brown dwarf because its mass is below the limiting mass for thermonuclear fusion of deuterium ....

s.

Cha 110913-773444
Cha 110913-773444
Cha 110913-773444 is an astronomical object surrounded by what appears to be a protoplanetary disk...

 may be an ejected rogue planet, or it may have formed on its own and be a sub-brown dwarf. Astronomers believe that either way, the definition of planet
Definition of planet
The definition of planet, since the word was coined by the ancient Greeks, has included within its scope a wide range of celestial bodies. Greek astronomers employed the term asteres planetai , "wandering stars", for objects which apparently move over the sky...

 should depend on current observable state, and not origin.

Retention of heat in interstellar space


In 1998, David J. Stevenson
David J. Stevenson
David John Stevenson is a professor of planetary science at Caltech. Originally from New Zealand, he received his Ph.D. from Cornell University in physics, where he proposed a model for the interior of Jupiter. He is well-known for applying fluid mechanics and magnetohydrodynamics to understand...

 theorized that some planet-sized objects drift in the vast expanses of cold interstellar space and could possibly sustain a thick atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

 which would not freeze out due to radiative heat loss. He proposes that atmospheres are preserved by the pressure-induced far-infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 radiation opacity of a thick hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

-containing atmosphere.

It is thought that during planetary system formation, several small protoplanetary bodies may be ejected from the forming system. With the reduced ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 light associated with its increasing distance from the parent star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

, the planet's predominantly hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

- and helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...

-containing atmosphere would be easily confined even by an Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

-sized body's gravity.

It is calculated that for an Earth-sized object at a kilobar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...

 hydrogen atmospheric pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...

s in which a convective gas adiabat
Adiabatic process
In thermodynamics, an adiabatic process or an isocaloric process is a thermodynamic process in which the net heat transfer to or from the working fluid is zero. Such a process can occur if the container of the system has thermally-insulated walls or the process happens in an extremely short time,...

 has formed, geothermal energy from residual core radioisotope decay will be sufficient to heat the surface to temperatures above the melting point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...

 of water. Thus, it is proposed that interstellar planetary bodies with extensive liquid water oceans may exist. It is further suggested that these planets are likely to remain geologically active for long periods, providing a geodynamo-created protective magnetosphere
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...

 and possible sea floor volcanism
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....

 which could provide an energy source for life. The author admits these bodies will be difficult to detect due to the intrinsically weak thermal microwave radiation emissions emanating from the lower reaches of the atmosphere, although later research suggests that reflected solar radiation and far-IR thermal emissions may be detected if one were to pass within 1000 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

 of Earth.

A study of simulated planet ejection scenarios has suggested that around five percent of Earth-sized planets with Moon-sized moons would retain their moons after ejection. A large moon would be a source of significant geological tidal heating.

Proplyds of planetars


Recently, it has been discovered that some extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...

s such as the planemo 2M1207b
2M1207b
2M1207b is a planetary-mass object orbiting the brown dwarf 2M1207, in the constellation Centaurus, approximately 170 light-years from Earth...

, orbiting the brown dwarf 2M1207, have debris discs. If some large interstellar objects are considered stars (sub-brown dwarfs), then the debris could coalesce into planets, meaning the disks are proplyds. If these are considered planets, then the debris would coalesce as moons. The term planetar
Planetar (astronomy)
Planetar is a term used in astronomy that refers to one of two things:* Brown dwarfs — objects intermediate in size between planets and stars — but having formed similarly to planets....

 exists for those accretion masses that seem to fall between stars and planets.

Interstellar planets in popular culture


In the novel When Worlds Collide
When Worlds Collide
When Worlds Collide is a 1933 science fiction novel co-written by Philip Wylie and Edwin Balmer; they both also co-authored the sequel After Worlds Collide...

(1933, serialisation began 1932) by Edwin Balmer
Edwin Balmer
Edwin Balmer was an American science fiction and mystery writer. He was born in Chicago to Helen Clark and Thomas Balmer. In 1909, he married Katharine MacHarg, sister of the writer William MacHarg. After her death, he married Grace A. Kee in 1927.He began as a reporter for the Chicago Tribune...

 and Phillip Wylie, Earth is first devastated, and then destroyed, by "Bronson Alpha", a gas-giant-sized rogue planet, orbited by "Bronson Beta", an Earth-sized satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

. Fortunately, advance warning enables several groups of survivors to escape to Bronson Beta, whose orbit maps onto that of the destroyed Earth, and is torn away from its former primary by the gravitational impact of the Bronson Alpha/Earth collision. A cinematic version of the book was produced in a 1951 film of the same name.

In the 1951 film, When Worlds Collide
When Worlds Collide (film)
When Worlds Collide is a 1951 science fiction film based on the 1933 novel co-written by Philip Gordon Wylie and Edwin Balmer. The film was shot in Technicolor, directed by Rudolph Maté and was the winner of the 1951 Academy Award for special effects....

, a cinematic incarnation of the 1933 book of the same name, Bronson Alpha was reimagined as a dwarf star and renamed "Bellus", while Bronson Beta was designated "Zyra."

The short story A Pail of Air
A Pail of Air
"A Pail of Air" is a science fiction short story by Fritz Leiber which appeared in the December 1951 issue of Galaxy Magazine and was dramatized on the radio show X Minus One in March 1956.-Plot:...

by Fritz Leiber
Fritz Leiber
Fritz Reuter Leiber, Jr. was an American writer of fantasy, horror and science fiction. He was also a poet, actor in theatre and films, playwright, expert chess player and a champion fencer. Possibly his greatest chess accomplishment was winning clear first in the 1958 Santa Monica Open.. With...

, which first appeared in the December 1951 issue of Galaxy Magazine and aired on the radio drama X Minus One
X Minus One
X Minus One was a half-hour science fiction radio drama series broadcast from April 24, 1955 to January 9, 1958 in various timeslots on NBC.-Overview:...

in March 1956, is narrated by a boy living on Earth after it has been torn from the Sun's gravity and captured by a passing "dark star". Although Earth now orbits this "dark star" (which might be a black hole
Black hole
A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...

 or cool brown dwarf), it shares many characteristics with an interstellar planet.

In the 1959 novel Wolfbane
Wolfbane (novel)
Wolfbane is a science fiction novel by Frederik Pohl and C. M. Kornbluth, published in 1959. It was serialized in Galaxy in 1957, with illustrations by Wally Wood....

by Frederik Pohl
Frederik Pohl
Frederik George Pohl, Jr. is an American science fiction writer, editor and fan, with a career spanning over seventy years — from his first published work, "Elegy to a Dead Planet: Luna" , to his most recent novel, All the Lives He Led .He won the National Book Award in 1980 for his novel Jem...

 and C. M. Kornbluth (originally serialised in Galaxy
Galaxy Science Fiction
Galaxy Science Fiction was an American digest-size science fiction magazine, published from 1950 to 1980. It was founded by an Italian company, World Editions, which was looking to break in to the American market. World Editions hired as editor H. L...

in 1957) a rogue planet, populated by strange machines known as Pyramids, steals the Earth from the Solar system, taking it off into interstellar space.

In The Wanderer (Fritz Leiber novel)
The Wanderer (Fritz Leiber novel)
The Wanderer is the title of a science fiction novel by Fritz Leiber about a wandering planet that enters the solar system...

, Earth encounters two ambulatory rogue planets. One, The Wanderer, is inhabited by nonconformist felinoid aliens, while The Stranger is a 'police world' that is pursuing the renegade felinoids. There are gravitational and tidal upheavals and the Moon is destroyed.

In the 1966 novel The Witches of Karres
The Witches of Karres
The Witches of Karres is a novel by James H. Schmitz. It is his best known book, and is considered a science fiction classic. It falls within the genre of space opera and features well-developed characters, a mix of both fantasy and hard science fiction as well as a sense of humor...

 by James H. Schmitz
James H. Schmitz
James Henry Schmitz was an American writer born in Hamburg, Germany of American parents.- Life :Aside from two years at business school in Chicago, Schmitz lived in Germany until 1938, leaving before World War II broke out in Europe in 1939.During World War II, Schmitz served as an aerial...

, expanded from a 1949 novelette, the rogue planet Karres can be moved through space by means of witchcraft
Witchcraft
Witchcraft, in historical, anthropological, religious, and mythological contexts, is the alleged use of supernatural or magical powers. A witch is a practitioner of witchcraft...

.

In the 1966 Doctor Who
Doctor Who
Doctor Who is a British science fiction television programme produced by the BBC. The programme depicts the adventures of a time-travelling humanoid alien known as the Doctor who explores the universe in a sentient time machine called the TARDIS that flies through time and space, whose exterior...

story The Tenth Planet
The Tenth Planet
The Tenth Planet is a serial in the British science fiction television series Doctor Who, which was first broadcast in four weekly parts from 8 October to 29 October 1966. It was William Hartnell's last regular appearance as the First Doctor, and the first story to feature the Cybermen...

, Mondas, home of the Cybermen, is said be Earth's twin which was knocked out of Solar orbit during prehistoric times, returning in 1986. In Revenge of the Cybermen
Revenge of the Cybermen
Revenge of the Cybermen is a serial in the British science fiction television series Doctor Who, which was first broadcast in four weekly parts from 19 April to 10 May 1975.-Synopsis:...

, the Cybermen waged war on the inhabitants of a rogue planetoid, the remnants of the destroyed planet Voga. The Star Trek: The Original Series
Star Trek: The Original Series
Star Trek is an American science fiction television series created by Gene Roddenberry, produced by Desilu Productions . Star Trek was telecast on NBC from September 8, 1966, through June 3, 1969...

episode "The Squire of Gothos" is set on a rogue planet, uninhabitable except for a small patch maintained by a superhuman being.

The first known use of "rogue planet" as term for such detached worlds occurred in Poul Anderson
Poul Anderson
Poul William Anderson was an American science fiction author who began his career during one of the Golden Ages of the genre and continued to write and remain popular into the 21st century. Anderson also authored several works of fantasy, historical novels, and a prodigious number of short stories...

's 1969 Polesotechnic League novel Satan's World.

In the British science-fiction television series, Space: 1999
Space: 1999
Space: 1999 is a British science-fiction television series that ran for two seasons and originally aired from 1975 to 1977. In the opening episode, nuclear waste from Earth stored on the Moon's far side explodes in a catastrophic accident on 13 September 1999, knocking the Moon out of orbit and...

, the Earth's Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 is knocked out of orbit by an explosion at its nuclear waste dump. The Moon then becomes a wandering planet.

The rogue planet of Worlorn is the scene of action in George R. R. Martin
George R. R. Martin
George Raymond Richard Martin , sometimes referred to as GRRM, is an American author and screenwriter of fantasy, horror, and science fiction. He is best known for A Song of Ice and Fire, his bestselling series of epic fantasy novels that HBO adapted for their dramatic pay-cable series Game of...

’s novel Dying of the Light
Dying of the Light
Dying of the Light is a 1977 science fiction novel by George R. R. Martin, his first. Martin's original title for the novel was "After the Festival" but was later changed before its first hardcover publication.; it was nominated for both the Hugo Award for Best Novel in 1978, and the British...

.

In the Warhammer 40,000
Warhammer 40,000
Warhammer 40,000 is a tabletop miniature wargame produced by Games Workshop, set in a dystopian science fantasy universe. Warhammer 40,000 was created by Rick Priestley in 1987 as the futuristic companion to Warhammer Fantasy Battle, sharing many game mechanics...

universe, the Temple of the Culexus Assassins of the Officio Assassinorum is located deep under the surface of a 'dead' rogue planet. In the Red Dwarf
Red Dwarf
Red Dwarf is a British comedy franchise which primarily comprises eight series of a television science fiction sitcom that aired on BBC Two between 1988 and 1999 and Dave from 2009–present. It gained cult following. It was created by Rob Grant and Doug Naylor, who also wrote the first six series...

 books, the Earth becomes a rogue planet when it is torn from its orbit by exploding sewage.

The homeworld of the Founders in Star Trek: Deep Space Nine
Star Trek: Deep Space Nine
Star Trek: Deep Space Nine is a science fiction television series set in the Star Trek universe...

is a rogue planet in a nebula; it has climatic conditions capable of supporting humanoid life.

From the 2nd season of Mainframe Entertainment
Mainframe Entertainment
Rainmaker Entertainment, Inc. is a Canadian computer animation and design company based in Vancouver, British Columbia and Los Angeles, California. It produces computer animation TV series and movies. They are best known for producing the first ever CGI animated series ReBoot, as well as the...

's War Planets cartoon onward, the titular planets were forced to become rogue planets in order to escape being consumed by the Beast Planet, which they achieved with colossal "World Engine" propulsion systems created by a lost civilization..

The planet Zonama Sekot in the Star Wars
Star Wars
Star Wars is an American epic space opera film series created by George Lucas. The first film in the series was originally released on May 25, 1977, under the title Star Wars, by 20th Century Fox, and became a worldwide pop culture phenomenon, followed by two sequels, released at three-year...

 fictional universe was first introduced in the novel Rogue Planet
Rogue Planet (novel)
Rogue Planet is a 2000 novel set in the Star Wars galaxy. It is a prequel novel occurring after the events of Star Wars Episode I: The Phantom Menace. The book was written by Greg Bear. The cover art was by David Stevenson...

and later expanded on in the New Jedi Order series. The planet, which is in fact a sentient life form itself, is home to life unlike any other in the galaxy, including organic spaceships.

Rogue planets feature in two of American science fiction author Jack McDevitt
Jack McDevitt
Jack McDevitt is an American science fiction author whose novels frequently deal with attempts to make contact with alien races, and with archaeology or xenoarchaeology....

's novels Deepsix (2001) and Seeker (2005)
Seeker (novel)
Seeker is a 2005 science fiction novel by Jack McDevitt. It won the Nebula Award for Best Novel in 2006.-Synopsis:The story is set approximately 10,000 years in the future, after civilization has expanded to inhabit countless worlds...

.

In the Star Trek: Enterprise
Star Trek: Enterprise
Star Trek: Enterprise is a science fiction television series. It follows the adventures of humanity's first warp 5 starship, the Enterprise, ten years before the United Federation of Planets shown in previous Star Trek series was formed.Enterprise premiered on September 26, 2001...

episode "Rogue Planet", Enterprise happens upon a rogue planet with an Earth-like atmosphere. The planet was heated by volcanic vents that sent heat into the atmosphere, thus sustaining the ecology of the planet.

In the novel Sunstorm
Sunstorm (novel)
Sunstorm is a 2005 science fiction novel co-written by Arthur C. Clarke and Stephen Baxter. It is the second book in the series A Time Odyssey. The books in this series are often likened to the Space Odyssey series, although the Time Odyssey novels ostensibly deal with time where the...

, by Arthur C. Clarke
Arthur C. Clarke
Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction author, inventor, and futurist, famous for his short stories and novels, among them 2001: A Space Odyssey, and as a host and commentator in the British television series Mysterious World. For many years, Robert A. Heinlein,...

 and Stephen Baxter
Stephen Baxter
Stephen Baxter is a prolific British hard science fiction author. He has degrees in mathematics and engineering.- Writing style :...

, the eponymous sunstorm
Solar storm
Solar storm can refer to:*Solar flare, a large explosion in the Sun's atmosphere*Coronal mass ejection , a massive burst of solar wind associated with solar flares*Geomagnetic storm, the interaction of the Sun's outburst with Earth's magnetic field...

 is caused by the impact into the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 of a gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...

 diverted from Altair roughly two thousand years before. As it passed through the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

, it was visible as the Star of Bethlehem
Star of Bethlehem
In Christian tradition, the Star of Bethlehem, also called the Christmas Star, revealed the birth of Jesus to the magi, or "wise men", and later led them to Bethlehem. The star appears in the nativity story of the Gospel of Matthew, where magi "from the east" are inspired by the star to travel to...

.

In the film Melancholia by Lars von Trier
Lars von Trier
Lars von Trier is a Danish film director and screenwriter. He is closely associated with the Dogme 95 collective, although his own films have taken a variety of different approaches, and have frequently received strongly divided critical opinion....

, the fictional rogue planet Melancholia is an important part of the storyline.

See also

  • Brown dwarf
    Brown dwarf
    Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...

  • Sub-brown dwarf
    Sub-brown dwarf
    A sub-brown dwarf is an astronomical object of planetary mass that is not orbiting a star and is not considered to be a brown dwarf because its mass is below the limiting mass for thermonuclear fusion of deuterium ....

  • Planetar
    Planetar (astronomy)
    Planetar is a term used in astronomy that refers to one of two things:* Brown dwarfs — objects intermediate in size between planets and stars — but having formed similarly to planets....

  • Interstellar comet
    Interstellar comet
    An interstellar comet is a comet that hypothetically exists in the interstellar medium, that is, it is not gravitationally bound to a star. Although none has yet been conclusively identified, it is suspected that there must be a large population of these bodies...

  • Intergalactic star
    Intergalactic star
    An intergalactic star is a star which does not belong to a galaxy. These stars were a source of much discussion in the scientific community during the late 1990s and are generally thought to be the result of colliding galaxies.-Discovery:...


External links