A
binary system is an
astronomicalAstronomy is the scientific study of celestial objects and phenomena that originate outside the Earth's atmosphere...
term referring to two objects in space (usually
starA star is a massive, luminous ball of plasma that is held together by gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth. Other stars are visible in the night sky, when they are not outshone by the Sun...
s, but also
planetA planet , is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s,
galaxiesA 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 name is from the Greek root galaxias [γαλαξίας], meaning "milky," a reference...
or
asteroidthumb|260px|right|[[253 Mathilde]], a [[C-type asteroid]] measuring about across. Photograph taken in 1997 by the [[NEAR Shoemaker]] probe.Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are...
s) which are so close that their gravitational interaction causes them to orbit about a common
center of massThe center of mass of a system of particles is a specific point where, for many purposes, the system behaves as if its mass were concentrated there. The center of mass is a function only of the positions and masses of the particles that compose the system...
. Some definitions (e.g. that of
double planet"Double planet" is an informal term used to describe a planet with a moon that may be large enough to be considered a planet in its own right; a common definition is that the objects orbit a centre of gravity that is above their surfaces. The formal term is "binary system"...
, but not that of
binary starA binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
) require that this center of mass is not located within the interior of either object. A
multiple system is like a binary system but consists of three or more objects.
When binary asteroids are similar in size, they may be called "
binary companionsA binary asteroid is a system of two asteroids orbiting their common center of mass, in analogy with binary stars. 243 Ida was the first binary asteroid to be identified when the Galileo spacecraft did a flyby in 1993...
" instead of referring to the smaller body as a satellite.
Discussion
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A
binary system is an
astronomicalAstronomy is the scientific study of celestial objects and phenomena that originate outside the Earth's atmosphere...
term referring to two objects in space (usually
starA star is a massive, luminous ball of plasma that is held together by gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth. Other stars are visible in the night sky, when they are not outshone by the Sun...
s, but also
planetA planet , is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s,
galaxiesA 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 name is from the Greek root galaxias [γαλαξίας], meaning "milky," a reference...
or
asteroidthumb|260px|right|[[253 Mathilde]], a [[C-type asteroid]] measuring about across. Photograph taken in 1997 by the [[NEAR Shoemaker]] probe.Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are...
s) which are so close that their gravitational interaction causes them to orbit about a common
center of massThe center of mass of a system of particles is a specific point where, for many purposes, the system behaves as if its mass were concentrated there. The center of mass is a function only of the positions and masses of the particles that compose the system...
. Some definitions (e.g. that of
double planet"Double planet" is an informal term used to describe a planet with a moon that may be large enough to be considered a planet in its own right; a common definition is that the objects orbit a centre of gravity that is above their surfaces. The formal term is "binary system"...
, but not that of
binary starA binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
) require that this center of mass is not located within the interior of either object. A
multiple system is like a binary system but consists of three or more objects.
Binary companion (asteroids)
When binary asteroids are similar in size, they may be called "
binary companionsA binary asteroid is a system of two asteroids orbiting their common center of mass, in analogy with binary stars. 243 Ida was the first binary asteroid to be identified when the Galileo spacecraft did a flyby in 1993...
" instead of referring to the smaller body as a satellite. A good example of a true binary companion is the
90 Antiope90 Antiope is an asteroid discovered on October 1, 1866 by Robert Luther. The 90th asteroid to be discovered, it is named after Antiope from Greek mythology, though it is disputed as to whether this is Antiope the Amazon or Antiope the mother of Amphion and Zethus.Antiope orbits in the outer third...
system.
In popular culture
- Binary suns and star systems feature heavily in the Star Wars
Star Wars is an epic space opera franchise initially conceived by George Lucas. The first film in the franchise was originally released on May 25, 1977, by 20th Century Fox, and became a worldwide pop culture phenomenon, spawning two immediate sequels, released at three-year intervals...
films and related material, the most notable example being the system in which the planet TatooineTatooine is a fictional planet and setting for many key scenes in the Star Wars saga, appearing in every Star Wars film except The Empire Strikes Back. Since it is the home planet of Anakin Skywalker and Luke Skywalker, it is also one of the most iconic planets in the Star Wars universe.Tatooine...
is located.
- In the Discovery program Alien Planet
Alien Planet is a 94 minute special on Discovery Channel about two internationally built robot probes searching for alien life on the fictional planet Darwin IV. It was based on the book Expedition, by sci-fi/fantasy artist and writer Wayne Douglas Barlowe, who was also executive producer on the...
, the planet Darwin IVDarwin IV is a fictional planet that was the subject of Wayne Barlowe's book Expedition and the television special, Alien Planet, based on Expedition...
orbits a binary system.
- In Star Trek
Star Trek is an American science fiction entertainment series.The original Star Trek was an American television series, created by Gene Roddenberry, which debuted in 1966 and ran for three seasons, following the interstellar adventures of Captain James T. Kirk and the crew of the Federation...
, the planets Romulus and Remus are a binary system.
- In Spore
Spore is a multi-genre single-player metaverse god game developed by Maxis and designed by Will Wright. The game was released for the Microsoft Windows and Macintosh operating systems in September 2008. Spore is also available for direct download from EA games...
, there are solar systems with two suns.
- In Escape To Witch Mountain and Return From Witch Mountain, Tony and Tia's home planet orbits 2 suns
- "Futurama
Futurama is an animated American sci-fi sitcom created by Matt Groening and developed by Groening and David X. Cohen for the Fox network. The series follows the adventures of a late 20th-century New York City pizza delivery boy, Philip J...
" has an ep with two suns
See also
- Binary asteroid
A binary asteroid is a system of two asteroids orbiting their common center of mass, in analogy with binary stars. 243 Ida was the first binary asteroid to be identified when the Galileo spacecraft did a flyby in 1993...
- Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
- Contact binary
In astronomy, a contact binary is a binary star system whose component stars are so close that they touch each other or have merged to share a common gaseous envelope. A binary system whose stars share an envelope may also be called an overcontact or common envelope binary...
- Contact binary (asteroid)
In the study of asteroids, a contact binary is caused when two asteroids gravitate toward each other until they touch, forming an oddly-shaped single body. Asteroids suspected of being contact binaries include the unusually elongated 624 Hektor and the bilobated 216 Kleopatra and 4769 Castalia...
- Double planet
"Double planet" is an informal term used to describe a planet with a moon that may be large enough to be considered a planet in its own right; a common definition is that the objects orbit a centre of gravity that is above their surfaces. The formal term is "binary system"...
- Rotational Brownian motion
In astronomy, rotational Brownian motion refers to the random walk in orientation of a binary star's orbital plane, induced by gravitational perturbations from passing stars....