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Jupiter is the fifth
planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equilibrium, rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and ...

planet
from the
Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its own gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many othe ...

Sun
and the largest in the Solar System. It is a
gas giant A gas giant is a giant planet The giant planets constitute a diverse type of planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equilib ...
with a
mass Mass is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or "equal", or by assigning a numerical value ...
more than two and a half times that of all the other planets in the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

Solar System
combined, but slightly less than one-thousandth the mass of the Sun. Jupiter is the third-brightest natural object in the
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wi ...

Earth
's night sky after the
Moon The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia (continent), Australia), it is the largest natural satellite in the Solar System relative to the size of its plane ...

Moon
and
Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the brightest natural object in Earth's night sky after the Moon, Venus can ...

Venus
. It has been observed since pre-historic times and is named after the Roman god Jupiter, the king of the gods, because of its observed size. Jupiter is primarily composed of
hydrogen Hydrogen is the chemical element with the Symbol (chemistry), symbol H and atomic number 1. Hydrogen is the lightest element. At standard temperature and pressure, standard conditions hydrogen is a gas of diatomic molecules having the che ...

hydrogen
, but
helium Helium (from el, ἥλιος, helios Helios; Homeric Greek: ), Latinized as Helius; Hyperion and Phaethon are also the names of his father and son respectively. often given the epithets Hyperion ("the one above") and Phaethon ("the shining" ...

helium
constitutes one quarter of its mass and one tenth of its volume. It likely has a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. The on-going contraction of its interior generates heat greater than the amount received from the Sun. Because of its rapid rotation, the planet's shape is that of an
oblate spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric In mathematics, a quadric or quadric surface (quadric hypersurface in higher dimension thumb , 236px , The first four spatial dimensions, repres ...
; it has a slight but noticeable bulge around the equator. The outer atmosphere is visibly segregated into several bands at different latitudes, with turbulence and storms along their interacting boundaries. A prominent result of this is the
Great Red Spot The Great Red Spot is a persistent high-pressure region in the atmosphere of Jupiter The atmosphere of Jupiter is the largest planetary atmosphere in the Solar System. It is mostly made of molecular hydrogen and helium in roughly Sun#Compositi ...
, a giant storm that is known to have existed since at least the 17th century, when it was first seen by
telescope A telescope is an optical instrument An optical instrument (or "optic" for short) is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and determine their characteristic properties. Common ...

telescope
. Surrounding Jupiter is a faint
planetary ring A ring system is a disc or ring, orbiting an astronomical object In , an astronomical object or celestial object is a naturally occurring , association, or structure that exists in the . In , the terms ''object'' and ''body'' are often u ...
system and a powerful
magnetosphere In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses m ...

magnetosphere
. Jupiter's magnetic tail is nearly 800 million km long, covering the entire distance to
Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It only has one-eighth the average density of Earth; how ...

Saturn
's orbit. Jupiter has 80 known moons and possibly many more,Amateur Astronomer Discovers New Moon Orbiting Jupiter
Smithsonian Magazine, July 22, 2021
including the four large
Galilean moons The Galilean moons (or Galilean satellites) are the four largest moons of Jupiter—Io (moon), Io, Europa (moon), Europa, Ganymede (moon), Ganymede, and Callisto (moon), Callisto. They were first seen by Galileo Galilei in December 1609 or Janua ...
discovered by
Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei ( , ; 15 February 1564 – 8 January 1642), commonly referred to as Galileo, was an astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific q ...

Galileo Galilei
in 1610.
Ganymede
Ganymede
, the largest of these, has a diameter greater than that of the planet
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

Mercury
. ''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American , launched in 1972 and weighing , that completed the first mission to the . Thereafter, ''Pioneer 10'' became the to achieve the needed to . This project was conducted by the ...

Pioneer 10
'' was the first spacecraft to visit Jupiter, making its closest approach to the planet in December 1973. Jupiter has since been explored on a number of occasions by
robotic spacecraft 250px, An artist's interpretation of the '' MESSENGER'' spacecraft at Mercury A robotic spacecraft is an uncrewed spacecraft, usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often call ...
, beginning with the ''
Pioneer Pioneer commonly refers to a settler who migrates to previously uninhabited or sparsely inhabited land. In the United States pioneer commonly refers to an American pioneer, a person in American history who migrated west to join in settling and deve ...

Pioneer
'' and ''
Voyager Voyager may refer to: Computing and communications * LG Voyager The LG VX10000, also known as the Verizon Voyager or LG VX10K, is an Internet-enabled multimedia phone designed by LG Electronics and carried by Verizon Wireless, Telus, and Bel ...
'' flyby missions from 1973 to 1979, and later by the ''Galileo'' orbiter, which arrived at Jupiter in 1995. In 2007, Jupiter was visited by the ''
New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe that was launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research ...

New Horizons
'' probe, which
used Jupiter's gravity
used Jupiter's gravity
to increase its speed and bend its trajectory en route to
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 was the first and the largest Kuiper belt object to be discovered. After Pluto wa ...

Pluto
. The latest probe to visit the planet, ''
Juno Juno commonly refers to: *Juno (mythology), the Roman goddess of marriage and queen of the gods *Juno (film), ''Juno'' (film), 2007 Juno may also refer to: Arts, entertainment and media Fictional characters *Juno, in the film ''Jenny, Juno'' *Jun ...
'', entered orbit around Jupiter in July 2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of the moon
Europa Europa may refer to: Places *Europe Europe is a continent A continent is one of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven regions are commonly regard ...
. The
planetary symbol A planet symbol (or ''planetary symbol'') is a graphical symbol used in astrological symbol, astrology and astronomical symbol, astronomy to represent a classical planet (including the Sun and the Moon) or one of the modern planets. The symbols wer ...
for Jupiter, , descends from a Greek
zeta Zeta (, ; uppercase Ζ, lowercase ζ; grc, ζῆτα, el, ζήτα, label=Demotic Greek Demotic Greek or Dimotiki ( el, Δημοτική Γλώσσα, , , lit. "language of the people") was a colloquial vernacular form of Modern Greek, in c ...

zeta
with a horizontal stroke, , as an abbreviation for ''
Zeus Zeus or , , ; grc, Δῐός, ''Diós'', label=genitive In grammar In linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Ling ...

Zeus
'' (the Greek name for the planet).


Formation and migration

Jupiter is most likely the oldest planet in the Solar System. Current models of Solar System formation suggest that Jupiter formed at or beyond the
snow line The climatic snow line is the boundary between a snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further chang ...
; a distance from the early Sun where the temperature is sufficiently cold for
volatiles Volatiles are the group of chemical elements and chemical compounds that can be readily Volatility (chemistry), vaporized. In contrast with volatiles, elements and compounds that are not readily vaporized are known as Refractory (planetary scien ...
such as water to condense into solids. It first assembled a large solid core before accumulating its gaseous atmosphere. As a consequence, the core must have formed before the solar nebula began to dissipate after 10 million years. Formation models suggest Jupiter grew to 20 times the mass of the Earth in under a million years. The orbiting mass created a gap in the disk, thereafter slowly increasing to 50 Earth masses in 3–4 million years. According to the " grand tack hypothesis", Jupiter would have begun to form at a distance of roughly 3.5 . As the young planet accreted mass, interaction with the gas disk orbiting the Sun and
orbital resonance . Conjunctions ''Conjunctions'' is a biannual American literature, American literary journal based at Bard College. It was founded in 1981 and is currently edited by Bradford Morrow. Morrow received the PEN/Nora Magid Award for Magazine Editing ...
s with Saturn caused it to migrate inward. This would have upset the orbits of what are believed to be super-Earths orbiting closer to the Sun, causing them to collide destructively. Saturn would later have begun to migrate inwards too, much faster than Jupiter, leading to the two planets becoming locked in a 3:2 mean motion resonance at approximately 1.5 AU. This in turn would have changed the direction of migration, causing them to migrate away from the Sun and out of the inner system to their current locations. These migrations would have occurred over an 800,000 year time period, with all of this happening over a time period of up to 6 million years after Jupiter began to form (3 million being a more likely figure). This departure would have allowed the formation of the inner planets from the rubble, including Earth. However, the formation timescales of terrestrial planets resulting from the grand tack hypothesis appear inconsistent with the measured terrestrial composition. Moreover, the likelihood that the outward migration actually occurred in the
solar nebula The formation and evolution of the Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital letter (uppercase letter) ...
is very low. In fact, some models predict the formation of Jupiter's analogues whose properties are close to those of the planet at the current epoch. Other models have Jupiter forming at distances much further out, such as 18 AU. In fact, based on Jupiter's composition, researchers have made the case for an initial formation outside the
molecular nitrogen Nitrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...
(N2) snowline, which is estimated at 20-30 AU, and possibly even outside the argon snowline, which may be as far as 40 AU. Having formed at one of these extreme distances, Jupiter would then have migrated inwards to its current location. This inward migration would have occurred over a roughly 700,000 year time period, during an epoch approximately 2–3 million years after the planet began to form. Saturn, Uranus and Neptune would have formed even further out than Jupiter, and Saturn would also have migrated inwards.


Physical characteristics

Jupiter is one of the two
gas giant A gas giant is a giant planet The giant planets constitute a diverse type of planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equilib ...
s, being primarily composed of gas and liquid rather than solid matter. It is the largest planet in the Solar System, with a diameter of at its
equator The Equator is a circle of latitude, about in circumference, that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the N ...

equator
. The average density of Jupiter, 1.326 g/cm3, is the second highest of the giant planets, but lower than those of the four
terrestrial planet A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate Rock (geology), rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Su ...
s.


Composition

Jupiter's upper atmosphere is about 90% hydrogen and 10% helium by volume. Since helium atoms are more massive than hydrogen molecules, Jupiter's atmosphere is approximately 75% hydrogen and 24% helium by mass, with the remaining one percent consisting of other elements. The atmosphere contains trace amounts of
methane Methane (, ) is a chemical compound with the chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes a ...
,
water vapour (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous p ...
,
ammonia Ammonia is a chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula NH3. A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct ch ...

ammonia
, and
silicon Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...

silicon
-based compounds. There are also fractional amounts of
carbon Carbon (from la, carbo "coal") is a with the C and 6. It is lic and —making four s available to form s. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 percent of Earth's crust. Three occur naturally, ...

carbon
,
ethane Ethane ( or ) is an organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), organ Chemistry * Organic matter, matter that has come from a once-living ...
,
hydrogen sulfide Hydrogen sulfide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by havi ...

hydrogen sulfide
,
neon Neon is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that co ...

neon
,
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
,
phosphine Phosphine (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Science ...

phosphine
, and
sulfur Sulfur (in nontechnical British English: sulphur) is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: th ...

sulfur
. The outermost layer of the atmosphere contains
crystal A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformatio ...

crystal
s of frozen ammonia. Through
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior ...

infrared
and
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, ...

ultraviolet
measurements, trace amounts of
benzene Benzene is an organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), organ Chemistry * Organic matter, matter that has come from a once-living organ ...

benzene
and other
hydrocarbon In organic chemistry Organic chemistry is a branch of chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, prop ...
s have also been found. The interior of Jupiter contains denser materials—by mass it is roughly 71% hydrogen, 24% helium, and 5% other elements. The atmospheric proportions of hydrogen and helium are close to the theoretical composition of the primordial
solar nebula The formation and evolution of the Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital letter (uppercase letter) ...
. Neon in the upper atmosphere only consists of 20 parts per million by mass, which is about a tenth as abundant as in the Sun. Helium is also depleted to about 80% of the Sun's helium composition. This depletion is a result of
precipitation In meteorology Meteorology is a branch of the (which include and ), with a major focus on . The study of meteorology dates back , though significant progress in meteorology did not begin until the 18th century. The 19th century saw mod ...
of these elements as helium-rich droplets deep in the interior of the planet. Based on
spectroscopy Spectroscopy is the study of the interaction Interaction is a kind of action that occurs as two or more objects have an effect upon one another. The idea of a two-way effect is essential in the concept of interaction, as opposed to a one-way ...

spectroscopy
, Saturn is thought to be similar in composition to Jupiter, but the other giant planets
Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus, who, according to Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and ...

Uranus
and
Neptune Neptune is the eighth and farthest-known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, slightly mo ...

Neptune
have relatively less hydrogen and helium and relatively more of the next most abundant elements, including oxygen, carbon, nitrogen, and sulfur. As their volatile compounds are mainly in ice form, they are called
ice giant An ice giant is a giant planet The giant planets constitute a diverse type of planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equili ...
s.


Mass and size

Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—this is so massive that its
barycentre In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses ...
with the Sun lies above the Sun's surface at 1.068 
solar radii Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the Optical_depth_(astrophysics), optical depth eq ...
from the Sun's centre. Jupiter is much larger than Earth and considerably less dense: its volume is that of about 1,321 Earths, but it is only 318 times as massive. Jupiter's radius is about one tenth the radius of the Sun, and its mass is one thousandth the
mass of the Sun The solar mass () is a standard mass#Units of mass, unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as star cluster, stellar clusters, nebulae, galaxy, galaxies and Black hole, b ...
, so the densities of the two bodies are similar. A "
Jupiter mass Jupiter mass, also called Jovian mass, is the unit of mass equal to the total mass of the planet Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant A gas giant is a giant planet comp ...
" ( or ) is often used as a unit to describe masses of other objects, particularly
extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917, but was not recognized as such. The first confirmation of detection occurred in 1992. This was followed by the ...
s and
brown dwarfs A brown dwarf is a type of substellar object that has a mass between the most massive gas giant planets and the least massive stars, approximately 13 to 80 Jupiter mass, times that of Jupiter (). Unlike main sequence stars, brown dwarfs do not a ...
. For example, the extrasolar planet
HD 209458 b HD 209458 b, also given the nickname Osiris, is an exoplanet that orbits the Solar twin, solar analog HD 209458 in the constellation Pegasus (constellation), Pegasus, some from the Solar System. The radius of the planet's orbit is , or one-eighth ...

HD 209458 b
has a mass of , while Kappa Andromedae b has a mass of . Theoretical models indicate that if Jupiter had much more mass than it does at present, it would shrink. For small changes in mass, the
radius In classical geometry Geometry (from the grc, γεωμετρία; ' "earth", ' "measurement") is, with , one of the oldest branches of . It is concerned with properties of space that are related with distance, shape, size, and relative ...

radius
would not change appreciably, and above 160% of the current mass the interior would become so much more compressed under the increased pressure that its volume would ''decrease'' despite the increasing amount of matter. As a result, Jupiter is thought to have about as large a diameter as a planet of its composition and evolutionary history can achieve. The process of further shrinkage with increasing mass would continue until appreciable stellar ignition was achieved, as in high-mass
brown dwarf A brown dwarf is a type of substellar object that has a mass between the most massive gas giant planets and the least massive stars, approximately 13 to 80 Jupiter mass, times that of Jupiter (). Unlike main sequence stars, brown dwarfs do not a ...

brown dwarf
s having around 50 Jupiter masses. Although Jupiter would need to be about 75 times more massive to fuse hydrogen and become a
star A star is an astronomical object consisting of a luminous spheroid of plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral) or heliotrope, a mineral aggregate * Quark ...

star
, the smallest
red dwarf A red dwarf is the smallest and coolest kind of star on the main sequence. Red dwarfs are by far the most common type of star in the Milky Way, at least in the neighborhood of the Sun, but because of their low luminosity, individual red dwarfs c ...
is only about 30 percent larger in radius than Jupiter. Despite this, Jupiter still radiates more heat than it receives from the Sun; the amount of heat produced inside it is similar to the total
solar radiation Solar irradiance is the power Power typically refers to: * Power (physics) In physics, power is the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one j ...
it receives. This additional heat is generated by the
Kelvin–Helmholtz mechanism The Kelvin–Helmholtz mechanism is an astronomy, astronomical process that occurs when the surface of a star or a planet cools. The cooling causes the internal pressure to drop, and the star or planet shrinks as a result. This compression, in turn ...
through contraction. This process causes Jupiter to shrink by about 1 mm/yr. When formed, Jupiter was hotter and was about twice its current diameter.


Internal structure

Before the early 21st century, most scientists expected Jupiter to either consist of a dense
core Core or cores may refer to: Science and technology * Core (anatomy) In common parlance, the core of the body is broadly considered to be the torso. Functional movements are highly dependent on this part of the body, and lack of core muscular dev ...
, a surrounding layer of liquid
metallic hydrogen Metallic hydrogen is a phase of hydrogen Hydrogen is the chemical element with the Symbol (chemistry), symbol H and atomic number 1. With a standard atomic weight of , hydrogen is the lightest element in the periodic table. Hydrogen is t ...
(with some helium) extending outward to about 80% of the radius of the planet, and an outer atmosphere consisting predominantly of
molecular hydrogen Hydrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the sam ...
, or perhaps to have no core at all, consisting instead of denser and denser fluid (predominantly molecular and metallic hydrogen) all the way to the center, depending on whether the planet accreted first as a solid body or collapsed directly from the gaseous
protoplanetary disk A protoplanetary disk is a rotating circumstellar disc A circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accumulation of matter composed of gas, Cosmic dust, dust, planetesimals, asteroids, or collision fragments i ...

protoplanetary disk
. When the ''Juno'' mission arrived in July 2016, it found that Jupiter has a very diffuse core that mixes into its mantle. A possible cause is an impact from a planet of about ten Earth masses a few million years after Jupiter's formation, which would have disrupted an originally solid Jovian core. It is estimated that the core is 30–50% of the planet's radius, and contains heavy elements 7–25 times the mass of Earth. Above the layer of metallic hydrogen lies a transparent interior atmosphere of hydrogen. At this depth, the pressure and temperature are above molecular hydrogen's
critical pressure In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, radiation, and physical properties of matter. The behavior of these quantities is govern ...
of 1.3
MPa MPA or mPa may refer to: Academia Academic degrees * Master of Performing Arts * Master of Professional Accountancy * Master of Public Administration * Master of Public Affairs Schools * Mesa Preparatory Academy * Morgan Park Academy * Mounds ...
and
critical temperature Critical or Critically may refer to: *Critical, or critical but stable, medical states **Critical, or intensive care medicine * Critical juncture, a discontinuous change studied in the social sciences. *Critical Software, a company specializing in ...
of only 33 . In this state, there are no distinct liquid and gas phases—hydrogen is said to be in a supercritical fluid state. It is convenient to treat hydrogen as gas extending downward from the cloud layer to a depth of about 1,000 , and as liquid in deeper layers, possibly resembling something akin to an
ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
of liquid hydrogen and other supercritical fluids. Physically, there is no clear boundary—the gas smoothly becomes hotter and denser as depth increases. Rain-like droplets of helium and neon precipitate downward through the lower atmosphere, depleting the abundance of these elements in the upper atmosphere. Calculations suggest that helium drops separate from metallic hydrogen at a radius of 60,000 km (11,000 km below the cloudtops) and merge again at 50,000 km (22,000 km beneath the clouds). Rainfalls of
diamonds Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At Standard conditions for temperature and pressure, room temperature and pressure, another solid form of c ...
have been suggested to occur, as well as on Saturn and the ice giants Uranus and Neptune. The temperature and pressure inside Jupiter increase steadily inward, this is observed in microwave emission and required because the heat of formation can only escape by convection. At the pressure level of 10 bar (unit), bars (1
MPa MPA or mPa may refer to: Academia Academic degrees * Master of Performing Arts * Master of Professional Accountancy * Master of Public Administration * Master of Public Affairs Schools * Mesa Preparatory Academy * Morgan Park Academy * Mounds ...
), the temperature is around . The hydrogen is always supercritical (that is, it never encounters a first-order phase transition) even as it changes gradually from a molecular fluid to a metallic fluid at around 100–200 GPa, where the temperature is perhaps . The temperature of Jupiter's diluted core is estimated at around or more with an estimated pressure of around 4,500 GPa.


Atmosphere

Jupiter has the deepest planetary atmosphere in the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

Solar System
, spanning over in altitude.


Cloud layers

Jupiter is perpetually covered with clouds composed of ammonia crystals, and possibly ammonium hydrosulfide. The clouds are in the tropopause and are in bands of different latitudes, known as tropical regions. These are subdivided into lighter-hued ''zones'' and darker ''belts''. The interactions of these conflicting Atmospheric circulation, circulation patterns cause storms and turbulence. Wind speeds of are common in Jet stream#Other planets, zonal jet streams. The zones have been observed to vary in width, colour and intensity from year to year, but they have remained sufficiently stable for scientists to name them. The cloud layer is about deep, and consists of at least two decks of clouds: a thick lower deck and a thin clearer region. There may also be a thin layer of Water (properties), water clouds underlying the ammonia layer. Supporting the presence of water clouds are the flashes of lightning detected in the atmosphere of Jupiter. These electrical discharges can be up to a thousand times as powerful as lightning on Earth. The water clouds are assumed to generate thunderstorms in the same way as terrestrial thunderstorms, driven by the heat rising from the interior. The Juno mission revealed the presence of "shallow lightning" which originates from ammonia-water clouds relatively high in the atmosphere. These discharges carry "mushballs" of water-ammonia slushes covered in ice, which fall deep into the atmosphere. Upper-atmospheric lightning has been observed in Jupiter's upper atmosphere, bright flashes of light that last around 1.4 milliseconds. These are known as "elves" or "sprites" and appear blue or pink due to the hydrogen. The orange and brown colours in the clouds of Jupiter are caused by upwelling compounds that change colour when they are exposed to ultraviolet light from the Sun. The exact makeup remains uncertain, but the substances are thought to be phosphorus, sulfur or possibly hydrocarbons. These colourful compounds, known as chromophores, mix with the warmer lower deck of clouds. The zones are formed when rising convection cells form crystallising ammonia that masks out these lower clouds from view. Jupiter's low axial tilt means that the poles always receive less
solar radiation Solar irradiance is the power Power typically refers to: * Power (physics) In physics, power is the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one j ...
than the planet's equatorial region. Convection within the interior of the planet transports energy to the poles, balancing out the temperatures at the cloud layer.


Great Red Spot and other vortices

The best known feature of Jupiter is the
Great Red Spot The Great Red Spot is a persistent high-pressure region in the atmosphere of Jupiter The atmosphere of Jupiter is the largest planetary atmosphere in the Solar System. It is mostly made of molecular hydrogen and helium in roughly Sun#Compositi ...
, a persistent anticyclone, anticyclonic storm located 22° south of the equator. It is known to have existed since at least 1831, and possibly since 1665. Images by the Hubble Space Telescope have shown as many as two "red spots" adjacent to the Great Red Spot. The storm is visible through Earth-based
telescope A telescope is an optical instrument An optical instrument (or "optic" for short) is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and determine their characteristic properties. Common ...

telescope
s with an aperture of 12 cm or larger. The oval object rotation, rotates counterclockwise, with a period (physics), period of about six days. The maximum altitude of this storm is about above the surrounding cloudtops. The Spot's composition and the source of its red color remain uncertain, although photodissociated
ammonia Ammonia is a chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula NH3. A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct ch ...

ammonia
reacting with acetylene is a robust candidate to explain the coloration. The Great Red Spot is larger than the Earth. Mathematical models suggest that the storm is stable and will be a permanent feature of the planet. However, it has significantly decreased in size since its discovery. Initial observations in the late 1800s showed it to be approximately across. By the time of the ''
Voyager Voyager may refer to: Computing and communications * LG Voyager The LG VX10000, also known as the Verizon Voyager or LG VX10K, is an Internet-enabled multimedia phone designed by LG Electronics and carried by Verizon Wireless, Telus, and Bel ...
'' flybys in 1979, the storm had a length of and a width of approximately . ''Hubble'' observations in 1995 showed it had decreased in size to , and observations in 2009 showed the size to be . , the storm was measured at approximately , and was decreasing in length by about per year. In October 2021, a ''Juno'' flyby mission utilized two scientific instruments to measure the depth of the Great Red Spot putting it at around 300 - 500 km (186 -310 miles) deep. ''Juno'' missions show that there are several polar cyclone groups at Jupiter's poles. The northern group contains nine cyclones, with a large one in the center and eight others around it, while its southern counterpart also consists of a center vortex but is surrounded by five large storms and a single smaller one. These polar structures are caused by the turbulence in Jupiter's atmosphere and can be compared with the Saturn's hexagon, hexagon at Saturn's north pole. In 2000, an atmospheric feature formed in the southern hemisphere that is similar in appearance to the Great Red Spot, but smaller. This was created when smaller, white oval-shaped storms merged to form a single feature—these three smaller white ovals were first observed in 1938. The merged feature was named Oval BA and has been nicknamed "Red Spot Junior." It has since increased in intensity and changed from white to red. In April 2017, a "Great Cold Spot" was discovered in Jupiter's thermosphere at its Jupiter's North Pole, north pole. This feature is across, wide, and cooler than surrounding material. While this spot changes form and intensity over the short term, it has maintained its general position in the atmosphere for more than 15 years. It may be a giant vortex similar to the Great Red Spot, and appears to be Metastability, quasi-stable like the Vorticity, vortices in Earth's thermosphere. Interactions between charged particles generated from Io and the planet's strong magnetic field likely resulted in redistribution of heat flow, forming the Spot.


Magnetosphere

Jupiter's magnetic field is fourteen times stronger than Earth's, ranging from 4.2 gauss (unit), gauss (0.42 millitesla, mT) at the equator to 10–14 gauss (1.0–1.4 mT) at the poles, making it the strongest in the Solar System (except for sunspots). This field is thought to be generated by eddy currents—swirling movements of conducting materials—within the liquid metallic hydrogen core. The volcanoes on the moon Io (moon), Io emit large amounts of sulfur dioxide, forming a gas torus along the moon's orbit. The gas is Ionization, ionised in the
magnetosphere In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses m ...

magnetosphere
, producing sulfur and oxygen ions. They, together with hydrogen ions originating from the atmosphere of Jupiter, form a plasma sheet in Jupiter's equatorial plane. The plasma in the sheet co-rotates with the planet, causing deformation of the dipole magnetic field into that of a magnetodisk. Electrons within the plasma sheet generate a strong radio signature that produces bursts in the range of 0.6–30 hertz, MHz which are detectable from Earth with consumer-grade shortwave radio receivers. At about 75 Jupiter radii from the planet, the interaction of the magnetosphere with the solar wind generates a bow shock. Surrounding Jupiter's magnetosphere is a magnetopause, located at the inner edge of a magnetosheath—a region between it and the bow shock. The solar wind interacts with these regions, elongating the magnetosphere on Jupiter's lee side and extending it outward until it nearly reaches the orbit of Saturn. The four largest moons of Jupiter all orbit within the magnetosphere, which protects them from the solar wind. The magnetosphere of Jupiter is responsible for intense episodes of Radio wave, radio emission from the planet's polar regions. Volcanic activity on Jupiter's moon Io injects gas into Jupiter's magnetosphere, producing a torus of particles about the planet. As Io moves through this torus, the interaction generates Alfvén waves that carry ionised matter into the polar regions of Jupiter. As a result, radio waves are generated through a cyclotron Astrophysical maser, maser mechanism, and the energy is transmitted out along a cone-shaped surface. When Earth intersects this cone, the radio emissions from Jupiter can exceed the solar radio output.


Orbit and rotation

Jupiter is the only planet whose
barycentre In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses ...
with the Sun lies outside the volume of the Sun, though by only 7% of the Sun's radius. The average distance between Jupiter and the Sun is 778 million km (about 5.2 times the average distance between Earth and the Sun, or 5.2 Astronomical unit, AU) and it completes an orbit every 11.86 years. This is approximately two-fifths the orbital period of Saturn, forming a near
orbital resonance . Conjunctions ''Conjunctions'' is a biannual American literature, American literary journal based at Bard College. It was founded in 1981 and is currently edited by Bradford Morrow. Morrow received the PEN/Nora Magid Award for Magazine Editing ...
. The orbital plane of Jupiter is orbital inclination, inclined 1.31° compared to Earth. Because the Orbital eccentricity, eccentricity of its orbit is 0.048, Jupiter is slightly over 75 million km nearer the Sun at perihelion than aphelion. The axial tilt of Jupiter is relatively small, only 3.13°, so its seasons are insignificant compared to those of Earth and Mars. Jupiter's Period of revolution, rotation is the fastest of all the Solar System's planets, completing a rotation on its Coordinate axis, axis in slightly less than ten hours; this creates an equatorial bulge easily seen through an amateur telescope. The planet is an oblate spheroid, meaning that the diameter across its
equator The Equator is a circle of latitude, about in circumference, that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the N ...

equator
is longer than the diameter measured between its geographic pole, poles. On Jupiter, the equatorial diameter is longer than the polar diameter. Because Jupiter is not a solid body, its upper atmosphere undergoes differential rotation. The rotation of Jupiter's polar atmosphere is about 5 minutes longer than that of the equatorial atmosphere; three systems are used as frames of reference, particularly when graphing the motion of atmospheric features. System I applies to latitudes from 10° N to 10° S; its period is the planet's shortest, at 9h 50m 30.0s. System II applies at all latitudes north and south of these; its period is 9h 55m 40.6s. System III was defined by radio astronomers and corresponds to the rotation of the planet's magnetosphere; its period is Jupiter's official rotation.


Observation

Jupiter is usually the List of brightest natural objects in the sky, fourth brightest object in the sky (after the Sun, the
Moon The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia (continent), Australia), it is the largest natural satellite in the Solar System relative to the size of its plane ...

Moon
, and
Venus Venus is the second planet from the Sun. It is named after the Venus (mythology), Roman goddess of love and beauty. As List of brightest natural objects in the sky, the brightest natural object in Earth's night sky after the Moon, Venus can ...

Venus
); at Opposition (astronomy), opposition Mars#Viewing, Mars can appear brighter than Jupiter. Depending on Jupiter's position with respect to the Earth, it can vary in visual magnitude from as bright as −2.94 at Opposition (astronomy), opposition down to −1.66 during Conjunction (astronomy and astrology), conjunction with the Sun. The mean apparent magnitude is −2.20 with a standard deviation of 0.33. The angular diameter of Jupiter likewise varies from 50.1 to 29.8 arc seconds. Favorable oppositions occur when Jupiter is passing through Apsis, perihelion, an event that occurs once per orbit. Because the orbit of Jupiter is outside that of Earth, the Phase angle (astronomy), phase angle of Jupiter as viewed from Earth never exceeds 11.5°; thus, Jupiter always appears nearly fully illuminated when viewed through Earth-based telescopes. It was only during spacecraft missions to Jupiter that crescent views of the planet were obtained. A small telescope will usually show Jupiter's four
Galilean moons The Galilean moons (or Galilean satellites) are the four largest moons of Jupiter—Io (moon), Io, Europa (moon), Europa, Ganymede (moon), Ganymede, and Callisto (moon), Callisto. They were first seen by Galileo Galilei in December 1609 or Janua ...
and the prominent cloud belts across Jupiter's atmosphere. A large telescope will show Jupiter's Great Red Spot when it faces Earth.


History of research and exploration


Pre-telescopic research

Observation of Jupiter dates back to at least the Babylonian astronomy, Babylonian astronomers of the 7th or 8th century BC. The ancient Chinese knew Jupiter as the "''Suì'' Star" ( ) and established their cycle of 12 earthly branches based on its approximate number of years; the Chinese language still uses its name (simplified characters, simplified as ) when referring to years of age. By the 4th century BC, these observations had developed into the Chinese zodiac, with each year associated with a Tai Sui Chinese astronomy, star and Chinese gods, god controlling the region of the heavens opposite Jupiter's position in the night sky; these beliefs survive in some Taoist Chinese folk religion, religious practices and in the East Asian zodiac's twelve animals, now often folk etymology, popularly assumed to be related to the arrival of the animals before Chinese Buddhism, Buddha. The Chinese historian Xi Zezong has claimed that Gan De, an ancient Chinese astronomy, Chinese astronomer, reported a small star "in alliance" with the planet, which may indicate a sighting of one of Moons of Jupiter, Jupiter's moons with the unaided eye. If true, this would predate Galileo's discovery by nearly two millennia. A 2016 paper reports that trapezoidal rule was used by Babylonians before 50 BCE for integrating the velocity of Jupiter along the ecliptic. In his 2nd century work the ''Almagest'', the Hellenistic astronomer Claudius Ptolemaeus constructed a geocentric planetary model based on deferents and epicycles to explain Jupiter's motion relative to Earth, giving its orbital period around Earth as 4332.38 days, or 11.86 years.


Ground-based telescope research

In 1610, Italian polymath
Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei ( , ; 15 February 1564 – 8 January 1642), commonly referred to as Galileo, was an astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific q ...

Galileo Galilei
discovered the four largest moons of Jupiter (now known as the Galilean moons) using a telescope; thought to be the first telescopic observation of moons other than Earth's. One day after Galileo, Simon Marius independently discovered moons around Jupiter, though he did not publish his discovery in a book until 1614. It was Marius's names for the major moons, however, that stuck: Io, Europa, Ganymede, and Callisto (moon), Callisto. These findings were the first discovery of celestial mechanics, celestial motion not apparently centred on Earth. The discovery was a major point in favor of Nicolaus Copernicus, Copernicus' heliocentrism, heliocentric theory of the motions of the planets; Galileo's outspoken support of the Copernican theory led to him being tried and condemned by the Inquisition. During the 1660s, Giovanni Domenico Cassini, Giovanni Cassini used a new telescope to discover spots and colourful bands, observe that the planet appeared oblate, and estimate the planet's rotation period. In 1690 Cassini noticed that the atmosphere undergoes differential rotation. The Great Red Spot may have been observed as early as 1664 by Robert Hooke and in 1665 by Cassini, although this is disputed. The pharmacist Samuel Heinrich Schwabe, Heinrich Schwabe produced the earliest known drawing to show details of the Great Red Spot in 1831. The Red Spot was reportedly lost from sight on several occasions between 1665 and 1708 before becoming quite conspicuous in 1878. It was recorded as fading again in 1883 and at the start of the 20th century. Both Giovanni Alfonso Borelli, Giovanni Borelli and Cassini made careful tables of the motions of Jupiter's moons, allowing predictions of when the moons would pass before or behind the planet. By the 1670s, it was observed that when Jupiter was on the opposite side of the Sun from Earth, these events would occur about 17 minutes later than expected. Ole Rømer deduced that light does not travel instantaneously (a conclusion that Cassini had earlier rejected), and this timing discrepancy was used to estimate the speed of light. In 1892, E. E. Barnard observed a fifth satellite of Jupiter with the refractor at Lick Observatory in California. This moon was later named Amalthea (moon), Amalthea. It was the last planetary moon to be discovered directly by visual observation. An additional eight satellites were discovered before the flyby of the Voyager 1 probe in 1979. In 1932, Rupert Wildt identified absorption bands of ammonia and methane in the spectra of Jupiter. Three long-lived anticyclonic features termed white ovals were observed in 1938. For several decades they remained as separate features in the atmosphere, sometimes approaching each other but never merging. Finally, two of the ovals merged in 1998, then absorbed the third in 2000, becoming Oval BA.


Radiotelescope research

In 1955, Bernard Burke and Kenneth Franklin detected bursts of radio signals coming from Jupiter at 22.2 MHz. The period of these bursts matched the rotation of the planet, and they used this information to refine the rotation rate. Radio bursts from Jupiter were found to come in two forms: long bursts (or L-bursts) lasting up to several seconds, and short bursts (or S-bursts) lasting less than a hundredth of a second. Scientists discovered that there are three forms of radio signals transmitted from Jupiter: * Decametric radio bursts (with a wavelength of tens of metres) vary with the rotation of Jupiter, and are influenced by the interaction of Io with Jupiter's magnetic field. * Decimetric radio emission (with wavelengths measured in centimetres) was first observed by Frank Drake and Hein Hvatum in 1959. The origin of this signal was a torus-shaped belt around Jupiter's equator. This signal is caused by cyclotron radiation from electrons that are accelerated in Jupiter's magnetic field. * Thermal radiation is produced by heat in the atmosphere of Jupiter.


Exploration

Since 1973, a number of automated spacecraft have visited Jupiter, most notably the ''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American , launched in 1972 and weighing , that completed the first mission to the . Thereafter, ''Pioneer 10'' became the to achieve the needed to . This project was conducted by the ...

Pioneer 10
'' space probe, the first spacecraft to get close enough to Jupiter to send back revelations about its properties and phenomena. Flights to planets within the Solar System are accomplished at a cost in energy, which is described by the net change in velocity of the spacecraft, or delta-v. Entering a Hohmann transfer orbit from Earth to Jupiter from low Earth orbit requires a delta-v of 6.3 km/s, which is comparable to the 9.7 km/s delta-v needed to reach low Earth orbit. Gravitational slingshot, Gravity assists through planetary Gravitational slingshot, flybys can be used to reduce the energy required to reach Jupiter, albeit at the cost of a significantly longer flight duration.


Flyby missions

Beginning in 1973, several spacecraft have performed planetary flyby maneuvers that brought them within observation range of Jupiter. The
Pioneer Pioneer commonly refers to a settler who migrates to previously uninhabited or sparsely inhabited land. In the United States pioneer commonly refers to an American pioneer, a person in American history who migrated west to join in settling and deve ...

Pioneer
missions obtained the first close-up images of Jupiter's atmosphere and several of its moons. They discovered that the radiation fields near the planet were much stronger than expected, but both spacecraft managed to survive in that environment. The trajectories of these spacecraft were used to refine the mass estimates of the Jovian system. Radio occultations by the planet resulted in better measurements of Jupiter's diameter and the amount of polar flattening. Six years later, the
Voyager Voyager may refer to: Computing and communications * LG Voyager The LG VX10000, also known as the Verizon Voyager or LG VX10K, is an Internet-enabled multimedia phone designed by LG Electronics and carried by Verizon Wireless, Telus, and Bel ...
missions vastly improved the understanding of the Galilean moons and discovered Jupiter's rings. They also confirmed that the Great Red Spot was anticyclonic. Comparison of images showed that the Red Spot had changed hue since the Pioneer missions, turning from orange to dark brown. A torus of ionised atoms was discovered along Io's orbital path, and volcanoes were found on the moon's surface, some in the process of erupting. As the spacecraft passed behind the planet, it observed flashes of lightning in the night side atmosphere. The next mission to encounter Jupiter was the ''Ulysses (spacecraft), Ulysses'' solar probe. In February 1992, it performed a flyby maneuver to attain a polar orbit around the Sun. During this pass, the spacecraft studied Jupiter's magnetosphere. ''Ulysses'' has no cameras so no images were taken. A second flyby six years later was at a much greater distance. In 2000, the ''Cassini'' probe flew by Jupiter on its way to Saturn, and provided higher-resolution images. The ''
New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe that was launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research ...

New Horizons
'' probe flew by Jupiter in 2007 for a gravity assist en route to
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 was the first and the largest Kuiper belt object to be discovered. After Pluto wa ...

Pluto
. The probe's cameras measured plasma output from volcanoes on Io and studied all four Galilean moons in detail, as well as making long-distance observations of the outer moons Himalia (moon), Himalia and Elara (moon), Elara.


''Galileo'' mission

The first spacecraft to orbit Jupiter was the ''Galileo spacecraft, Galileo'' probe, which entered orbit on December 7, 1995. It orbited the planet for over seven years, conducting multiple flybys of all the Galilean moons and Amalthea (moon), Amalthea. The spacecraft also witnessed the impact of Comet Shoemaker–Levy 9 as it approached Jupiter in 1994, giving a unique vantage point for the event. Its originally designed capacity was limited by the failed deployment of its high-gain radio antenna, although extensive information was still gained about the Jovian system from ''Galileo''. A 340-kilogram titanium Galileo (spacecraft)#Galileo entry probe, atmospheric probe was released from the spacecraft in July 1995, entering Jupiter's atmosphere on December 7. It parachuted through of the atmosphere at a speed of about 2,575 km/h (1600 mph) and collected data for 57.6 minutes before the signal was lost at a pressure of about 23 atmosphere (pressure), atmospheres and a temperature of 153 °C. It melted thereafter, and possibly vapourised. The ''Galileo'' orbiter itself experienced a more rapid version of the same fate when it was deliberately steered into the planet on September 21, 2003, at a speed of over 50 km/s to avoid any possibility of it crashing into and possibly contaminating the moon Europa, Life on Europa, which may harbor life. Data from this mission revealed that hydrogen composes up to 90% of Jupiter's atmosphere. The recorded temperature was more than 300 °C (570 °F) and the windspeed measured more than 644 km/h (>400 mph) before the probes vapourised.


''Juno'' mission

file:PIA22690 - Jupiter in the Rearview Mirror (panorama).jpg, upright=2,
A photograph of Jupiter taken by the Juno (spacecraft), ''Juno'' spacecraft, at the end of a close flyby
(September 2018)
file:PIA22946-Jupiter-RedSpot-JunoSpacecraft-20190212.jpg, Jupiter, as seen by the ''Juno'' spacecraft
(February 12, 2019) NASA's Juno (spacecraft), ''Juno'' mission arrived at Jupiter on July 4, 2016, and was expected to complete thirty-seven orbits over the next twenty months. The mission plan called for ''Juno'' to study the planet in detail from a polar orbit. On August 27, 2016, the spacecraft completed its first fly-by of Jupiter and sent back the first ever images of Jupiter's north pole. ''Juno'' would complete 12 science orbits before the end of its budgeted mission plan, ending July 2018. In June of that year, NASA extended the mission operations plan to July 2021, and in January of that year the mission was extended to September 2025 with four lunar flybys: one of Ganymede, one of Europa, and two of Io. When ''Juno'' reaches the end of the mission, it will perform a controlled deorbit and disintegrate into Jupiter's atmosphere. During the mission, the spacecraft will be exposed to high levels of radiation from Magnetosphere of Jupiter, Jupiter's magnetosphere, which may cause future failure of certain instruments and risk collision with Jupiter's moons.


Canceled missions and future plans

There has been great interest in studying Jupiter's icy moons in detail because of the possibility of subsurface liquid oceans on Europa, Ganymede, and Callisto. Funding difficulties have delayed progress. NASA's ''Jupiter Icy Moons Orbiter, JIMO'' (''Jupiter Icy Moons Orbiter'') was cancelled in 2005. A subsequent proposal was developed for a joint NASA/ESA mission called EJSM/Laplace, with a provisional launch date around 2020. EJSM/Laplace would have consisted of the NASA-led Jupiter Europa Orbiter and the ESA-led Jupiter Ganymede Orbiter. However, ESA had formally ended the partnership by April 2011, citing budget issues at NASA and the consequences on the mission timetable. Instead, ESA planned to go ahead with a European-only mission to compete in its L1 Cosmic Vision selection. These plans were realized as the European Space Agency's Jupiter Icy Moon Explorer (JUICE), due to launch in 2023, followed by NASA's ''Europa Clipper'' mission, scheduled for launch in 2024. Other proposed missions include the Chinese National Space Administration's ''Interstellar Express'', a pair of probes to launch in 2024 that would use Jupiter's gravity to explore either end of the heliosphere, and NASA's ''Trident (spacecraft), Trident'', which would launch in 2025 and use Jupiter's gravity to bend the spacecraft on a path to explore
Neptune Neptune is the eighth and farthest-known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, slightly mo ...

Neptune
's moon Triton (moon), Triton.


Moons

Jupiter has 80 known natural satellites. Of these, 60 are less than 10 km in diameter. The four largest moons are Io, Europa, Ganymede, and Callisto, collectively known as the "
Galilean moons The Galilean moons (or Galilean satellites) are the four largest moons of Jupiter—Io (moon), Io, Europa (moon), Europa, Ganymede (moon), Ganymede, and Callisto (moon), Callisto. They were first seen by Galileo Galilei in December 1609 or Janua ...
", and are visible from Earth with binoculars on a clear night.


Galilean moons

The moons discovered by Galileo—Io, Europa, Ganymede, and Callisto—are among the largest in the Solar System. The orbits of three of them (Io, Europa, and Ganymede) form a pattern known as a Laplace resonance; for every four orbits that Io makes around Jupiter, Europa makes exactly two orbits and Ganymede makes exactly one. This resonance causes the gravitational effects of the three large moons to distort their orbits into elliptical shapes, because each moon receives an extra tug from its neighbors at the same point in every orbit it makes. The tidal force from Jupiter, on the other hand, works to Tidal circularization, circularise their orbits. The Orbital eccentricity, eccentricity of their orbits causes regular flexing of the three moons' shapes, with Jupiter's gravity stretching them out as they approach it and allowing them to spring back to more spherical shapes as they swing away. This tidal flexing Tidal acceleration#Tidal heating, heats the moons' interiors by friction. This is seen most dramatically in the Io (moon)#Volcanism, volcanic activity of Io (which is subject to the strongest tidal forces), and to a lesser degree in the geological youth of Europa (moon)#Surface features, Europa's surface, which indicates recent resurfacing of the moon's exterior.


Classification

Jupiter's moons were traditionally classified into four groups of four, based on commonality of their orbital elements. This picture has been complicated by the discovery of numerous small outer moons since 1999. Jupiter's moons are currently divided into several different groups, although there are several moons which are not part of any group. The eight innermost regular moons, which have nearly circular orbits near the plane of Jupiter's equator, are thought to have formed alongside Jupiter, whilst the remainder are irregular moons and are thought to be Asteroid capture, captured asteroids or fragments of captured asteroids. Irregular moons that belong to a group share similar orbital elements and thus may have a common origin, perhaps as a larger moon or captured body that broke up.


Planetary rings

Jupiter has a faint
planetary ring A ring system is a disc or ring, orbiting an astronomical object In , an astronomical object or celestial object is a naturally occurring , association, or structure that exists in the . In , the terms ''object'' and ''body'' are often u ...
system composed of three main segments: an inner torus of particles known as the halo, a relatively bright main ring, and an outer gossamer ring. These rings appear to be made of dust, rather than ice as with Saturn's rings. The main ring is probably made of material ejected from the satellites Adrastea (moon), Adrastea and Metis (moon), Metis. Material that would normally fall back to the moon is pulled into Jupiter because of its strong gravitational influence. The orbit of the material veers towards Jupiter and new material is added by additional impacts. In a similar way, the moons Thebe (moon), Thebe and Amalthea (moon), Amalthea probably produce the two distinct components of the dusty gossamer ring. There is also evidence of a rocky ring strung along Amalthea's orbit which may consist of collisional debris from that moon.


Interaction with the Solar System

Along with the Sun, the gravitational influence of Jupiter has helped shape the Solar System. The orbits of most of the system's planets lie closer to Jupiter's orbital plane (astronomy), orbital plane than the Sun's celestial equator, equatorial plane (
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

Mercury
is the only planet that is closer to the Sun's equator in orbital tilt). The Kirkwood gaps in the asteroid belt are mostly caused by Jupiter, and the planet may have been responsible for the Late Heavy Bombardment event in the inner Solar System's history. In addition to its moons, Jupiter's gravitational field controls numerous asteroids that have settled into the regions of the Lagrangian points preceding and following Jupiter in its orbit around the Sun. These are known as the Trojan asteroids, and are divided into List of Trojan asteroids (Greek camp), Greek and List of Trojan asteroids (Trojan camp), Trojan "camps" to commemorate the ''Iliad''. The first of these, 588 Achilles, was discovered by Max Wolf in 1906; since then more than two thousand have been discovered. The largest is 624 Hektor. Most List of periodic comets, short-period comets belong to the Jupiter family—defined as comets with semi-major axis, semi-major axes smaller than Jupiter's. Jupiter family comets are thought to form in the Kuiper belt outside the orbit of Neptune. During close encounters with Jupiter their orbits are Perturbation (astronomy), perturbed into a smaller period and then circularised by regular gravitational interaction with the Sun and Jupiter. Due to the magnitude of Jupiter's mass, the barycenter, centre of gravity between it and the Sun lies just above the Sun's surface, the only planet in the Solar System for which this is true.


Impacts

Jupiter has been called the Solar System's Comet Shoemaker–Levy 9#Jupiter as a "cosmic vacuum cleaner", vacuum cleaner because of its immense gravity well and location near the inner Solar System there are more List of Jupiter events, impacts on Jupiter, such as comets, than on the Solar System's other planets. It was thought that Jupiter partially shielded the inner system from cometary bombardment. However, recent computer simulations suggest that Jupiter does not cause a net decrease in the number of comets that pass through the inner Solar System, as its gravity perturbs their orbits inward roughly as often as it Accretion (astrophysics), accretes or ejects them. This topic remains controversial among scientists, as some think it draws comets towards Earth from the Kuiper belt while others think that Jupiter protects Earth from the Oort cloud. Jupiter experiences about 200 times more asteroid and comet impacts than Earth. In July 1994 the Comet Shoemaker–Levy 9 comet collided with the Jupiter. The event was closely observed by a wide range observatories around the world, including Hubble Space Telescope and Galilio probe. The event was widely covered by media. A 1997 survey of early astronomical records and drawings suggested that a certain dark surface feature discovered by astronomer Giovanni Domenico Cassini, Giovanni Cassini in 1690 may have been an impact scar. The survey initially produced eight more candidate sites as potential impact observations that he and others had recorded between 1664 and 1839. It was later determined, however, that these candidate sites had little or no possibility of being the results of the proposed impacts.


Mythology

The planet Jupiter has been known since ancient times. It is visible to the naked eye in the night sky and can occasionally be seen in the daytime when the Sun is low. To the Babylonians, this object represented their god Marduk. They used Jupiter's roughly 12-year orbit along the ecliptic to define the constellations of their zodiac. The Romans called it "the star of Jupiter (mythology), Jupiter" (''Iuppiter Stella''), as they believed it to be sacred to the principal List of Roman deities, god of Roman mythology, whose name comes from the Proto-Indo-European language, Proto-Indo-European vocative compound *''Dyēu-pəter'' (nominative: *''Dyeus, Dyēus-pətēr'', meaning "Father Sky-God", or "Father Day-God"). In turn, Jupiter was the counterpart to the Greek mythology, mythical Greek ''
Zeus Zeus or , , ; grc, Δῐός, ''Diós'', label=genitive In grammar In linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Ling ...

Zeus
'' (Ζεύς), also referred to as ''Dias'' (Δίας), the planetary name of which is retained in modern Greek language, Greek. The ancient Greeks knew the planet as Phaethon ( grc, Φαέθων, label=none), meaning "shining one" or "blazing star". As supreme god of the Roman pantheon, Jupiter was the god of thunder, lightning, and storms, and appropriately called the god of light and sky. file:Jupiter symbol (fixed width).svg, frameless, 100px The original Greek deity ''Zeus'' supplies the root ''zeno-'', used to form some Jupiter-related words, such as ''wikt:zenographic, zenographic''. ''Jovian'' is the Adjective, adjectival form of Jupiter. The older adjectival form ''jovial'', employed by astrologers in the Middle Ages, has come to mean "happy" or "merry", moods ascribed to Jupiter (astrology), Jupiter's astrological influence. In Germanic paganism, Germanic mythology, Jupiter is equated to Thor, whence the English name ''Thursday'' for the Roman ''dies Jovis''. In Jyotisha, Vedic astrology, Hindu astrologers named the planet after Brihaspati, the religious teacher of the gods, and often called it "Guru", which literally means the "Heavy One". In Turkic mythology, Central Asian Turkic myths, Jupiter is called ''Erendiz'' or ''Erentüz'', from ''eren'' (of uncertain meaning) and ''yultuz'' ("star"). There are many theories about the meaning of ''eren''. These peoples calculated the period of the orbit of Jupiter as 11 years and 300 days. They believed that some social and natural events connected to Erentüz's movements on the sky. The Chinese, Vietnamese, Koreans, and Japanese called it the "wood star" (), based on the Chinese Five elements (Chinese philosophy), Five Elements.


Gallery

File:Gemini North Infrared View of Jupiter.jpg, The tempestuous atmosphere of Jupiter, captured by the Wide Field Camera 3 on the Hubble Space Telescope in infrared. File:Hubble Visible View of Jupiter.jpg, Hubble Visible View of Jupiter File:Hubble Ultraviolet View of Jupiter.jpg, Hubble Ultraviolet View of Jupiter File:Hubble's View of Jupiter and Europa in August 2020.jpg, This image of Jupiter and Europa, taken by the NASA/ESA Hubble Space Telescope on 25 August 2020, was captured when the planet was 653 million kilometres from Earth


See also

* * * * * March 17, 2016 collision with Jupiter * *


Notes


References


External links

* * – A simulation of the 62 moons of Jupiter.
Jupiter in Motion
album of ''Juno'' imagery stitched into short videos
June 2010 impact video

Photographs of Jupiter circa 1920s from the Lick Observatory Records Digital Archive, UC Santa Cruz Library's Digital Collections

Interactive 3D gravity simulation of the Jovian system

Video (animation; 4:00): Flyby of Ganymede and Jupiter
(NASA; 15 July 2021). {{Authority control Jupiter, Articles containing video clips Astronomical objects known since antiquity Gas giants Outer planets