Jupiter
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Jupiter is the fifth
planet A planet is a large, rounded Astronomical object, astronomical body that is neither a star nor its Stellar remnant, remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud colla ...

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

Sun
and the largest in the Solar System. It is a
gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...
with a
mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a body. It was traditionally believed to be related to the physical quantity, quantity of matter in a Physical object, physical body, until the discovery of the atom and par ...
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 "Solar S ...

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 harbor life. While large list of largest lakes and seas in the Solar System, volumes of water can be found throughout the Solar System, only water distributi ...

Earth
's night sky after the
Moon The Moon is Earth's only natural satellite. It is the List of natural satellites, fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth ( ...

Moon
and
Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an Inferior and superior planets, interior planet to Earth, Venus (like Mercury (pl ...

Venus
, and it has been observed since
prehistoric times Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of ...
. It was named after the Roman god Jupiter, the king of the gods. 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 chemical ...
, but
helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol (chemistry), symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas gr ...
constitutes one-quarter of its mass and one-tenth of its volume. It probably has a rocky core of heavier elements, but, like the other
giant planet The giant planets constitute a diverse type of planet much larger than Earth. They are usually primarily composed of low-boiling-point materials (volatiles), rather than Rock (geology), rock or other solid matter, but massive solid planets can ...
s in the Solar System, it lacks a well-defined solid surface. The ongoing contraction of Jupiter's interior generates more heat than it receives from the Sun. Because of its rapid rotation, the planet's shape is an
oblate spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface (mathematics), surface obtained by Surface of revolution, rotating an ellipse about one of its principal axes; in other words, an ellipsoid with ...
: it has a slight but noticeable bulge around the equator. The outer atmosphere is divided into a series of latitudinal bands, 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 area, high-pressure region in the atmosphere of Jupiter, producing an anticyclonic storm that is the largest in the Solar System. Located 22 degree (angle), degrees south of Jupiter's equator, it p ...
, a giant storm which has been observed since at least 1831. Jupiter is surrounded by a faint
planetary ring A ring system is a disc or ring, orbiting an astronomical object, that is composed of solid material such as cosmic dust, dust and moonlets, and is a common component of satellite system (astronomy), satellite systems around giant planets. A ri ...
system and a powerful
magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...
. Jupiter's magnetic tail is nearly long, covering nearly 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 has only one-eighth the average density of Earth; h ...
's orbit. Jupiter has 82 known moons and likely many more, including the four large moons discovered by
Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
in 1610: Io,
Europa Europa may refer to: Places * Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continen ...
, Ganymede, and Callisto. Io and Europa are about the size of Earth's Moon; Callisto is almost the size of the planet Mercury, and Ganymede is larger. ''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the List of artificial objects leaving the S ...
'' was the first spacecraft to visit Jupiter, making its closest approach to the planet in December 1973. Jupiter has since been explored by multiple
robotic spacecraft A robotic spacecraft is an uncrewed spacecraft, usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rathe ...
, beginning with the '' Pioneer'' and ''
Voyager Voyager may refer to: Computing and communications * LG Voyager, a mobile phone model manufactured by LG Electronics * NCR Voyager, a computer platform produced by NCR Corporation * Voyager (computer worm), a computer worm affecting Oracle ...
'' flyby missions from 1973 to 1979, and later with the ''Galileo'' orbiter in 1995. In 2007, 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 ...
'' visited Jupiter using its gravity to increase its speed, bending 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 is the ninth-largest and tenth-most-massive known object to directly orbit the S ...
. The latest probe to visit the planet, '' Juno'', entered orbit around Jupiter in July 2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of Europa.


Name and symbol

In both the ancient Greek and Roman civilizations, Jupiter was named after the chief god of the divine
pantheon Pantheon may refer to: * Pantheon (religion), a set of gods belonging to a particular religion or tradition, and a temple or sacred building Arts and entertainment Comics *Pantheon (Marvel Comics), a fictional organization *Pantheon (Lone Star Pr ...
:
Zeus Zeus or , , ; grc, Δῐός, ''Diós'', label=Genitive case, genitive Aeolic Greek, Boeotian Aeolic and Doric Greek#Laconian, Laconian grc-dor, Δεύς, Deús ; grc, Δέος, ''Déos'', label=Genitive case, genitive el, Δίας, ''D ...
for the Greeks and
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
for the Romans. The
International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
(IAU) formally adopted the name Jupiter for the planet in 1976. The IAU names newly discovered satellites of Jupiter for the mythological lovers, favourites, and descendants of the god. The planetary symbol for Jupiter, , descends from a Greek
zeta Zeta (, ; uppercase Ζ, lowercase ζ; grc, ζῆτα, el, ζήτα, label=Demotic Greek, classical or ''zē̂ta''; ''zíta'') is the sixth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 7. It was derived fr ...
with a horizontal stroke, , as an abbreviation for ''Zeus''. Jove, the archaic name of Jupiter, came into use as a poetic name for the planet around the 14th century. The Romans named the fifth day of the week ''diēs Iovis'' ("Jove's Day") after the planet Jupiter. In
Germanic mythology Germanic mythology consists of the body of myths native to the Germanic peoples, including Norse mythology, Anglo-Saxon paganism#Mythology, Anglo-Saxon mythology, and Continental Germanic mythology. It was a key element of Germanic paganism. ...
, Jupiter is equated to
Thor Thor (; from non, Þórr ) is a prominent god in Germanic paganism. In Norse mythology, he is a hammer-wielding æsir, god associated with lightning, thunder, storms, sacred trees and groves in Germanic paganism and mythology, sacred groves ...
, whence the English name ''Thursday'' for the Roman ''dies Jovis''. The original Greek deity ''Zeus'' supplies the root ''zeno-'', which is used to form some Jupiter-related words, such as '' zenographic''. ''Jovian'' is the adjectival form of Jupiter. The older adjectival form ''jovial'', employed by astrologers in the
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the Post-classical, post-classical period of World history (field), global history. It began with t ...
, has come to mean "happy" or "merry", moods ascribed to Jupiter's influence in
astrology Astrology is a range of Divination, divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of Celestial o ...
.


Formation and migration

Jupiter is believed to be 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-covered and snow-free surface. The actual snow line may adjust seasonally, and be either significantly higher in elevation, or lower. The permanent snow line is the level above which snow wil ...
: a distance from the early Sun where the temperature is sufficiently cold for
volatiles Volatiles are the group of chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Un ...
such as water to condense into solids. The planet began as a solid core, which then accumulated its gaseous atmosphere. As a consequence, the planet must have formed before the solar nebula was fully dispersed. During its formation, Jupiter's mass gradually increased until it had 20 times the mass of the Earth (about half of which was made up of silicates, ices and other heavy-element constituents). When the proto-Jupiter grew larger than 50 Earth masses it created a gap in the solar nebula. Thereafter, the growing planet reached its final masses in 3–4 million years. According to the "
grand tack hypothesis In planetary astronomy, the grand tack hypothesis proposes that Jupiter formed at 3.5 astronomical unit, AU, then migrated inward to 1.5 AU, before reversing course due to capturing Saturn in an orbital resonance, eventually halting near its curren ...
", Jupiter began to form at a distance of roughly from the Sun. As the young planet accreted mass, interaction with the gas disk orbiting the Sun and
orbital resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...
s with Saturn caused it to migrate inward. This upset the orbits of several
super-Earth A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to t ...
s orbiting closer to the Sun, causing them to collide destructively. Saturn would later have begun to migrate inwards too, much faster than Jupiter, until the two planets became captured in a 3:2
mean motion resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...
at approximately from the Sun. This changed the direction of migration, causing them to migrate away from the Sun and out of the inner system to their current locations. All of this happened over a period of 3–6 million years, with the final migration of Jupiter occurring over several hundred thousand years. Jupiter's departure from the inner solar system eventually allowed the inner planets—including Earth—to form from the rubble. There are several problems with the grand tack hypothesis. The resulting formation timescales of terrestrial planets appear to be inconsistent with the measured elemental composition. It is likely that Jupiter would have settled into an orbit much closer to the Sun if it had migrated through the
solar nebula The formation of the Solar System began about 4.6 bya, billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened in ...
. Some competing models of Solar System formation predict the formation of Jupiter with orbital properties that are close to those of the present day planet. Other models predict Jupiter forming at distances much farther out, such as . Based on Jupiter's composition, researchers have made the case for an initial formation outside the molecular nitrogen (N2) snowline, which is estimated at from the Sun, and possibly even outside the argon snowline, which may be as far as . 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. In this model, Saturn, Uranus and Neptune would have formed even further out than Jupiter, and Saturn would also have migrated inwards.


Physical characteristics

Jupiter is a
gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...
, 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 ...
. The average density of Jupiter, 1.326 g/cm3, is about the same as
simple syrup Inverted sugar syrup, also called invert syrup, invert sugar, simple syrup, sugar syrup, sugar water, bar syrup, syrup USP, or sucrose inversion, is a syrup In cooking, a syrup (less commonly sirup; from ar, شراب; , beverage, wine ...
(syrup USP), and is 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 S ...
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 24% helium by mass. The atmosphere contains trace amounts of
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
,
water vapour (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 Joule, J/(Kilogram, kg·K) , - , Heat of vaporization , 2.27 Megajoule, MJ/kg , - , Heat capacity , 1.864 Kilojoule, kJ/(kg·K) Water vapor, water vapour or ...
,
ammonia Ammonia is an inorganic chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a dis ...
, 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 luster, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...
-based compounds. There are also fractional amounts of
carbon Carbon () is a chemical element with the chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—its atom making four electrons available to form covalent bond, covalent chemical bonds. It belongs to gro ...
,
ethane Ethane ( , ) is an Organic compound, organic chemical compound with chemical formula . At Standard conditions for temperature and pressure, standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane ...
,
hydrogen sulfide Hydrogen sulfide is a chemical compound with the chemical formula, formula . It is a colorless Chalcogen hydride, chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic ...
,
neon Neon is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical com ...
,
oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic table), group in the periodic table, a highly Chemical reaction, reactive nonmetal, and an oxidizing a ...
,
phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but chemical purity, technical grade samples have a highly Odor#Types, un ...
, and
sulfur Sulfur (or sulphur in British English British English (BrE, en-GB, or BE) is, according to Oxford Dictionaries, " English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the ...
. The outermost layer of the atmosphere contains
crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...
s of frozen ammonia. Through
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
and
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
measurements, trace amounts of
benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar Ring (chemistry), ring with one hydrogen atom ...
and other
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic, and their odors are usuall ...
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 of the Solar System began about 4.6 bya, billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened in ...
. 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 reduced to about 80% of the Sun's helium composition. This depletion is a result of
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, Rain and snow mixed, sleet, snow, ice pellets, ...
of these elements as helium-rich droplets, a process that happens deep in the interior of the planet. Based on
spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectrum, electromagnetic spectra that result from the interaction between Electromagnetism, electromagnetic radiation and matter as a function of the wavelengt ...
,
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 has only one-eighth the average density of Earth; h ...
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 (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
and
Neptune Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...
have relatively less hydrogen and helium and relatively more of the next most common elements, including oxygen, carbon, nitrogen, and sulfur. These planets are known as
ice giants An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune. In astrophysics and planetary science th ...
, because the majority of their
volatile Volatility or volatile may refer to: Chemistry * Volatility (chemistry) In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter t ...
compounds are in solid form.


Size and mass

Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—so massive that its
barycentre In astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. ...
with the Sun lies above the Sun's surface at 1.068  solar radii from the Sun's centre. Jupiter is much larger than Earth and considerably less dense: it has 1,321 times the volume of the Earth, but only 318 times the mass. 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 ...
, as 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 List of Solar System objects by size, largest in the Solar System. It is a gas gia ...
" ( 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. A different planet, init ...
s and
brown dwarf Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen Hydrogen is the chemical element with the Symbol (chemistry), symbol H and atomic number 1. Hydrogen ...
s. For example, the extrasolar planet HD 209458 b has a mass of , while Kappa Andromedae b has a mass of . Theoretical models indicate that if Jupiter had over 40% more mass, the interior would be so compressed that its volume would ''decrease'' despite the increasing amount of matter. For smaller changes in its mass, the
radius In classical geometry, a radius (plural, : radii) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', ...
would not change appreciably. 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. Although Jupiter would need to be about 75 times more massive to fuse hydrogen and become a
star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
, the smallest
red dwarf ''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave (TV channel), Dave since 2009, gaining a ...
may be only slightly larger in radius than Saturn. Jupiter radiates more heat than it receives through solar radiation, due to 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 tu ...
within its contracting interior. This process causes Jupiter to shrink by about /yr. When it formed, Jupiter was hotter and was about twice its current diameter.


Internal structure

Before the early 21st century, most scientists proposed one of two scenarios for the formation of Jupiter. If the planet accreted first as a solid body, it would consist of a dense core, a surrounding layer of liquid
metallic hydrogen Metallic hydrogen is a phase (matter), phase of hydrogen in which it behaves like an electrical conductor. This phase was predicted in 1935 on theoretical grounds by Eugene Wigner and Hillard Bell Huntington. At high pressure and temperatures, met ...
(with some helium) extending outward to about 80% of the radius of the planet, and an outer atmosphere consisting primarily of
molecular 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 chemical ...
. Alternatively, if the planet collapsed directly from the gaseous
protoplanetary disk A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a stellar evolution, young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may also be considered an accretion disk for th ...
, it was expected to completely lack a core, consisting instead of denser and denser fluid (predominantly molecular and metallic hydrogen) all the way to the centre. Data from the ''Juno'' mission showed that Jupiter has a very diffuse core that mixes into its mantle. This mixing process could have arisen during formation, while the planet accreted solids and gases from the surrounding nebula. Alternatively, it could have been caused by 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 takes up 30–50% of the planet's radius, and contains heavy elements with a combined mass 7–25 times the Earth. Outside 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 of 1.3 MPa 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 ...
of . In this state, there are no distinct liquid and gas phases—hydrogen is said to be in a
supercritical fluid A supercritical fluid (SCF) is any substance at a temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers a ...
state. The hydrogen and helium gas extending downward from the cloud layer gradually transitions to a liquid in deeper layers, possibly resembling something akin to an ocean of liquid hydrogen and other supercritical fluids. Physically, the gas gradually 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 ( below the cloudtops) and merge again at ( 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. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of car ...
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 because the heat of planetary formation can only escape by convection. At a surface depth where the atmospheric pressure level is , the temperature is around . The region of supercritical hydrogen changes gradually from a molecular fluid to a metallic fluid spans pressure ranges of with temperatures of , respectively. The temperature of Jupiter's diluted core is estimated to be with a pressure of around .


Atmosphere

The atmosphere of Jupiter extends to a depth of below the cloud layers.


Cloud layers

Jupiter is perpetually covered with clouds of ammonia crystals, which may contain
ammonium hydrosulfide Ammonium hydrosulfide is the chemical compound with the Chemical formula, formula . Composition It is the Salt (chemistry), salt derived from the ammonium cation and the hydrosulfide anion. The salt exists as colourless, water-soluble, micaceous ...
as well. The clouds are located in the
tropopause The tropopause is the atmospheric boundary that demarcates the troposphere The troposphere is the first and lowest layer of the Earth's atmosphere, atmosphere of the Earth, and contains 75% of the total mass of the Atmosphere, planetary atmosp ...
layer of the atmosphere, forming bands at different latitudes, known as tropical regions. These are subdivided into lighter-hued ''zones'' and darker ''belts''. The interactions of these conflicting circulation patterns cause storms and
turbulence In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by Chaos theory, chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disrup ...
. Wind speeds of are common in zonal jet streams. The zones have been observed to vary in width, colour and intensity from year to year, but they have remained stable enough for scientists to name them. The cloud layer is about deep, and consists of at least two decks of ammonia clouds: a thin clearer region on top with a thick lower deck. There may be a thin layer of
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
clouds underlying the ammonia clouds, as suggested by flashes of
lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
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 Upper-atmospheric lightning and ionospheric lightning are terms sometimes used by researchers to refer to a family of short-lived electrical-breakdown phenomena that occur well above the altitudes of normal lightning and storm clouds. Upper-atmo ...
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 made up of phosphorus, sulfur or possibly hydrocarbons. These colourful compounds, known as
chromophore A chromophore is the part of a molecule responsible for its color. The color that is seen by our eyes is the one not Absorption (electromagnetic radiation), absorbed by the reflecting object within a certain wavelength spectrum of visible spectrum ...
s, mix with the warmer clouds of the lower deck. The light-coloured zones are formed when rising
convection cell In the field of fluid dynamics, a convection cell is the phenomenon that occurs when density differences exist within a body of liquid or gas. These density differences result in rising and/or falling currents, which are the key characteristics ...
s form crystallising ammonia that hides the chromophores from view. Jupiter's low
axial tilt In astronomy, axial tilt, also known as obliquity, is the angle In Euclidean geometry, an angle is the figure formed by two Ray (geometry), rays, called the ''Side (plane geometry), sides'' of the angle, sharing a common endpoint, called ...
means that the poles always receive less
solar radiation Solar irradiance is the power (physics), power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per ...
than the planet's equatorial region.
Convection Convection is single or Multiphase flow, multiphase fluid flow that occurs Spontaneous process, spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoya ...
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 area, high-pressure region in the atmosphere of Jupiter, producing an anticyclonic storm that is the largest in the Solar System. Located 22 degree (angle), degrees south of Jupiter's equator, it p ...
, a persistent
anticyclonic An anticyclone is a weather meteorological phenomenon, phenomenon defined as a large-scale circulation of winds around a central high-pressure system, region of high atmospheric pressure, clockwise in the Northern Hemisphere and counterclockwise ...
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 The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of ...
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 a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally meaning only an optical instrument usin ...
s with an
aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of ray (optics), rays that come to a focus (optics), focus ...
of 12 cm or larger. The oval object rotates counterclockwise, with a
period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...
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 colour remain uncertain, although photodissociated
ammonia Ammonia is an inorganic chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a dis ...
reacting with
acetylene Acetylene (Chemical nomenclature, systematic name: ethyne) is the chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is ...
is a likely explanation. The Great Red Spot is larger than the Earth.
Mathematical model A mathematical model is a description of a system using mathematical concepts and language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languag ...
s 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, a mobile phone model manufactured by LG Electronics * NCR Voyager, a computer platform produced by NCR Corporation * Voyager (computer worm), a computer worm affecting Oracle ...
'' 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 measured the depth of the Great Red Spot, putting it at around . ''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 centre and eight others around it, while its southern counterpart also consists of a centre 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
hexagon In geometry, a hexagon (from Ancient Greek, Greek , , meaning "six", and , , meaning "corner, angle") or sexagon (from Latin , meaning "six") is a six-sided polygon or 6-gon creating the outline of a cube. The total of the internal angles of any ...
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 formed in 1939–1940. The merged feature was named
Oval BA 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#Composition, solar proportions; other chemical compounds are present only in small amounts and in ...
. It has since increased in intensity and changed from white to red, earning it the nickname "Little Red Spot". In April 2017, a "Great Cold Spot" was discovered in Jupiter's thermosphere at its
north pole The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's rotation, Earth's axis of rotation meets its surface. It is called the True North Pole to distingu ...
. 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 In fluid dynamics, a vortex (plural, : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools ...
similar to the Great Red Spot, and appears to be quasi-stable like the
vortices In fluid dynamics, a vortex (plural, : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools ...
in Earth's thermosphere. This feature may be formed by interactions between charged particles generated from Io and the strong magnetic field of Jupiter, resulting in a redistribution of heat flow.


Magnetosphere

Jupiter's
magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to t ...
is the strongest of any planet in the Solar System, with a dipole moment of that is tilted at an angle of 10.31° to the pole of rotation. The surface magnetic field strength varies from up to . This field is thought to be generated by
eddy current Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a magn ...
s—swirling movements of conducting materials—within the liquid metallic hydrogen core. At about 75 Jupiter radii from the planet, the interaction of the magnetosphere with the
solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...
generates a
bow shock In astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the eleme ...
. 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 Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference ...
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 volcanoes on the moon Io emit large amounts of
sulfur dioxide Sulfur dioxide ( IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcani ...
, forming a gas
torus In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanarity, coplanar with the circle. If the axis of revolution ...
along the moon's orbit. The gas is
ionized Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged a ...
in Jupiter's
magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...
, producing sulfur and oxygen
ion An ion () is an atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has n ...
s. They, together with hydrogen ions originating from the atmosphere of Jupiter, form a
plasma sheet In the magnetosphere, the plasma sheet is a sheet-like region of denser (0.3-0.5 ions/cm3 versus 0.01-0.02 in the lobes) hot Plasma (physics), plasma and lower magnetic field near the equatorial plane, between the magnetosphere's north and south lo ...
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, with short, superimposed bursts in the range of 0.6–30  MHz that are detectable from Earth with consumer-grade shortwave radio receivers. As Io moves through this torus, the interaction generates Alfvén waves that carry ionized matter into the polar regions of Jupiter. As a result, radio waves are generated through a
cyclotron A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Janu ...
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 radio output of the Sun.


Planetary rings

Jupiter has a faint
planetary ring A ring system is a disc or ring, orbiting an astronomical object, that is composed of solid material such as cosmic dust, dust and moonlets, and is a common component of satellite system (astronomy), satellite systems around giant planets. A ri ...
system composed of three main segments: an inner
torus In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanarity, coplanar with the circle. If the axis of revolution ...
of particles known as the halo, a relatively bright main ring, and an outer gossamer ring. These rings appear to be made of dust, while Saturn's rings are made of ice. The main ring is most likely made out of material ejected from the satellites Adrastea and Metis, which is drawn into Jupiter because of the planet's strong gravitational influence. New material is added by additional impacts. In a similar way, the moons Thebe and Amalthea are believed to produce the two distinct components of the dusty gossamer ring. There is evidence of a fourth ring that may consist of collisional debris from Amalthea that is strung along the same moon's orbit.


Orbit and rotation

Jupiter is the only planet whose
barycentre In astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. ...
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 (5.2 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 In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...
. The
orbital plane The orbital plane of a revolving body is the plane (geometry), geometric plane in which its orbit lies. Three non-line (geometry), collinear points in space suffice to determine an orbital plane. A common example would be the positions of the ce ...
of Jupiter is inclined 1.30° compared to Earth. Because the
eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior) Eccentricity (also called quirkiness) is an unusual or odd behavior on the part of an individual. This behavior would typically be perceived as unusual or unnecessary, without ...
of its orbit is 0.049, Jupiter is slightly over 75 million km nearer the Sun at
perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any e ...
than
aphelion An apsis (; ) is the farthest or nearest point in the orbit In celestial mechanics, an orbit is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a ...
. The
axial tilt In astronomy, axial tilt, also known as obliquity, is the angle In Euclidean geometry, an angle is the figure formed by two Ray (geometry), rays, called the ''Side (plane geometry), sides'' of the angle, sharing a common endpoint, called ...
of Jupiter is relatively small, only 3.13°, so its seasons are insignificant compared to those of Earth and Mars. Jupiter's
rotation Rotation, or spin, is the circular movement of an object around a ''axis of rotation, central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A t ...
is the fastest of all the Solar System's planets, completing a rotation on its
axis An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to: Mathematics * Axis of rotation: see rotation around a fixed axis *Axis (mathematics), a designator for a Cartesian-coordinate ...
in slightly less than ten hours; this creates an
equatorial bulge An equatorial bulge is a difference between the 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 imagina ...
easily seen through an amateur telescope. Because Jupiter is not a solid body, its upper atmosphere undergoes
differential rotation Differential rotation is seen when different parts of a rotating object move with different angular velocity, angular velocities (rates of rotation) at different latitudes and/or depths of the body and/or in time. This indicates that the object is ...
. The rotation of Jupiter's polar atmosphere is about 5 minutes longer than that of the equatorial atmosphere. 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 ...
is longer than the diameter measured between its
poles Poles,, ; singular masculine: ''Polak'', singular feminine: ''Polka'' or Polish people, are a West Slavs, West Slavic nation and ethnic group, who share a common History of Poland, history, Culture of Poland, culture, the Polish language and ...
. On Jupiter, the equatorial diameter is longer than the polar diameter. Three systems are used as frames of reference for tracking the planetary rotation, particularly when graphing the motion of atmospheric features. System I applies to latitudes from 7° N to 7° S; its period is the planet's shortest, at 9h 50 m 30.0s. System II applies at latitudes north and south of these; its period is 9h 55 m 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 fourth brightest object in the sky (after the Sun, the
Moon The Moon is Earth's only natural satellite. It is the List of natural satellites, fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth ( ...

Moon
, and
Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an Inferior and superior planets, interior planet to Earth, Venus (like Mercury (pl ...

Venus
), although at opposition
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmosph ...
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 down to −1.66 during
conjunction Conjunction may refer to: * Conjunction (grammar) In grammar In linguistics, the grammar of a natural language is its set of structure, structural constraints on speakers' or writers' composition of clause (linguistics), clauses, phrases, ...
with the Sun. The mean apparent magnitude is −2.20 with a standard deviation of 0.33. The
angular diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is ...
of Jupiter likewise varies from 50.1 to 30.5
arc second A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...
s. Favourable oppositions occur when Jupiter is passing through the
perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any e ...
of its orbit, bringing it closer to Earth. Near opposition, Jupiter will appear to go into
retrograde motion Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its Primary (astronomy), primary, that is, the central object (right figure). It may also describe other motions s ...
for a period of about 121 days, moving backward through an angle of 9.9° before returning to prograde movement. Because the orbit of Jupiter is outside that of Earth, the phase angle of Jupiter as viewed from Earth is always less than 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 Jan ...
and the prominent cloud belts across Jupiter's atmosphere. A larger telescope with an aperture of will show Jupiter's Great Red Spot when it faces Earth.


History


Pre-telescopic research

Observation of Jupiter dates back to at least the 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 The twelve Earthly Branches or Terrestrial Branches are a Chinese ordering system used throughout East Asia in various contexts, including its Sexagenary cycle, ancient dating system, Chinese astrology, astrological traditions, Chinese zodiac, z ...
based on the approximate number of years it takes Jupiter to rotate around the Sun; the
Chinese language Chinese (, especially when referring to written Chinese) is a group of languages spoken natively by the ethnic Han Chinese majority and List of ethnic groups in China, many minority ethnic groups in Greater China. About 1.3 billion people ( ...
still uses its name ( simplified as ) when referring to years of age. By the 4th century BC, these observations had developed into the
Chinese zodiac The Chinese zodiac is a traditional classification scheme based on the lunar calendar A lunar calendar is a calendar based on the monthly cycles of the Moon's lunar phase, phases (Lunar month#Synodic month, synodic months, lunations), in co ...
, and each year became associated with a Tai Sui
star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
and
god In monotheistic thought, God is usually viewed as the supreme being, creator, and principal object of faith. Swinburne, R.G. "God" in Honderich, Ted. (ed)''The Oxford Companion to Philosophy'', Oxford University Press, 1995. God is typicall ...
controlling the region of the heavens opposite Jupiter's position in the night sky. These beliefs survive in some
Taoist Taoism (, ) or Daoism () refers to either a school of Philosophy, philosophical thought (道家; ''daojia'') or to a religion (道教; ''daojiao''), both of which share ideas and concepts of China, Chinese origin and emphasize living in harmo ...
religious practices and in the East Asian zodiac's twelve animals. The Chinese historian
Xi Zezong Xi Zezong (June 6, 1927, Yuanqu County, Yuanqu, Shanxi – December 27, 2008, Beijing) was a Chinese astronomer, historian, and translator. He was a member of the Chinese Academy of Sciences, and an awardee of the Astronomy Prize. He identifie ...
has claimed that
Gan De Gan De (; Floruit, fl. 4th century BC), also known as the Lord Gan (Gan Gong), was an ancient Chinese astronomer and astrologer born in the State of Qi. Along with Shi Shen, he is believed to be the first in history known by name to compile a sta ...
, an ancient Chinese astronomer, reported a small star "in alliance" with the planet, which may indicate a sighting of one of 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 In calculus, the trapezoidal rule (also known as the trapezoid rule or trapezium rule; see Trapezoid for more information on terminology) is a technique for approximating the integral, definite integral. \int_a^b f(x) \, dx. The trapezoidal rul ...
was used by
Babylon ''Bābili(m)'' * sux, 𒆍𒀭𒊏𒆠 * arc, 𐡁𐡁𐡋 ''Bāḇel'' * syc, ܒܒܠ ''Bāḇel'' * grc-gre, Βαβυλών ''Babylṓn'' * he, בָּבֶל ''Bāvel'' * peo, 𐎲𐎠𐎲𐎡𐎽𐎢 ''Bābiru'' * elx, 𒀸𒁀𒉿𒇷 ''Babi ...
ians before 50 BCE for integrating the velocity of Jupiter along the
ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agai ...
. In his 2nd century work the ''
Almagest The ''Almagest'' is a 2nd-century Greek-language mathematical and astronomical treatise on the apparent motions of the stars and planetary paths, written by Claudius Ptolemy ( ). One of the most influential scientific texts in history, it ca ...
'', the Hellenistic astronomer
Claudius Ptolemaeus Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. ...
constructed a
geocentric In astronomy, the geocentric model (also known as geocentrism, often exemplified specifically by the Ptolemaic system) is a superseded scientific theories, superseded description of the Universe with Earth at the center. Under most geocentric mo ...
planetary model based on deferents and
epicycle In the Hipparchian, Ptolemaic, and Copernican systems of astronomy, the epicycle (, meaning "circle moving on another circle") was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Su ...
s 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) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
discovered the four largest moons of Jupiter (now 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 Jan ...
) using a telescope. This is thought to be the first telescopic observation of moons other than Earth's. Just 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. The discovery was a major point in favour of Copernicus'
heliocentric Heliocentrism (also known as the Heliocentric model) is the astronomical model in which the Earth and planets revolve around the Sun at the center of the universe. Historically, heliocentrism was opposed to Geocentric model, geocentrism, which p ...
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 The Inquisition was a group of institutions within the Catholic Church whose aim was to combat Christian heresy, heresy, conducting trials of suspected heretics. Studies of the records have found that the overwhelming majority of sentences consi ...
. During the 1660s,
Giovanni Cassini Giovanni Domenico Cassini, also known as Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was an Italian (naturalised French) mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the C ...
used a new telescope to discover spots and colourful bands in Jupiter's atmosphere, observe that the planet appeared oblate, and estimate its rotation period. In 1692, Cassini noticed that the atmosphere undergoes differential rotation. The Great Red Spot may have been observed as early as 1664 by
Robert Hooke Robert Hooke Fellow of the Royal Society, FRS (; 18 July 16353 March 1703) was an English polymath active as a scientist, natural philosopher and architect, who is credited to be one of two scientists to discover microorganisms in 1665 using ...
and in 1665 by Cassini, although this is disputed. The pharmacist
Heinrich Schwabe Samuel Heinrich Schwabe (25 October 1789 – 11 April 1875) a German astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronom ...
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 Borelli and Cassini made careful tables of the motions of Jupiter's moons, which allowed predictions of when the moons would pass before or behind the planet. By the 1670s, Cassini 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 Ole Christensen Rømer (; 25 September 1644 – 19 September 1710) was a Danish astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. Th ...
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 The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special relativity, special theory of relativity, is ...
. In 1892, E. E. Barnard observed a fifth satellite of Jupiter with the refractor at
Lick Observatory The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton (California), Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The ...
in California. This moon was later named Amalthea. It was the last planetary moon to be discovered directly by a visual observer through a telescope. An additional eight satellites were discovered before the flyby of the
Voyager 1 ''Voyager 1'' is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin ''Voyager 2'', ''Voyag ...
probe in 1979. In 1932, Rupert Wildt identified absorption bands of ammonia and methane in the spectra of Jupiter. Three long-lived anticyclonic features called "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 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#Composition, solar proportions; other chemical compounds are present only in small amounts and in ...
.


Space-based telescope research

On July 14, 2022, NASA presented images of Jupiter and related areas captured, for the first time, and including infrared views, by the
James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, List of the most distant astronomical ...
(JWST).


Radiotelescope research

In 1955, Bernard Burke and Kenneth Franklin discovered that Jupiter emits bursts of radio waves at a frequency of 22.2 MHz. The period of these bursts matched the rotation of the planet, and they used this information to determine a more precise value for Jupiter's 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 have discovered 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 is a torus-shaped belt around Jupiter's equator, which generates
cyclotron radiation Cyclotron radiation is electromagnetic radiation emitted by non-relativistic accelerating electric charge, charged particles deflected by a magnetic field. The Lorentz force on the particles acts perpendicular to both the magnetic field lines and t ...
from electrons that are accelerated in Jupiter's magnetic field. * Thermal radiation is produced by heat in the atmosphere of Jupiter.


Exploration

Jupiter has been visited by automated spacecraft since 1973, when the space probe ''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the List of artificial objects leaving the S ...
'' passed close enough to Jupiter to send back revelations about its properties and phenomena. Missions to Jupiter are accomplished at a cost in energy, which is described by the net change in velocity of the spacecraft, or
delta-v Delta-''v'' (more known as "Delta (letter)#Upper case, change in velocity"), symbolized as ∆''v'' and pronounced ''delta-vee'', as used in flight dynamics (spacecraft), spacecraft flight dynamics, is a measure of the impulse (physics), impuls ...
. Entering a
Hohmann transfer orbit In astronautics, the Hohmann transfer orbit () is an orbital maneuver used to transfer a spacecraft between two orbits of different altitudes around a central body. Examples would be used for travel between low Earth orbit and Moon, the Moon, ...
from Earth to Jupiter from
low Earth orbit A low Earth orbit (LEO) is an geocentric orbit, orbit around Earth with a orbital period, period of 128 minutes or less (making at least 11.25 orbits per day) and an orbital eccentricity, eccentricity less than 0.25. Most of the artificial object ...
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. Gravity assists through planetary flybys can be used to reduce the energy required to reach Jupiter.


Flyby missions

Beginning in 1973, several spacecraft have performed planetary flyby manoeuvres that brought them within observation range of Jupiter. The 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, a mobile phone model manufactured by LG Electronics * NCR Voyager, a computer platform produced by NCR Corporation * Voyager (computer worm), a computer worm affecting Oracle ...
missions vastly improved the understanding of the
Galilean moon 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 Jan ...
s and discovered Jupiter's rings. They also confirmed that the Great Red Spot was anticyclonic. Comparison of images showed that the Spot had changed hue since the Pioneer missions, turning from orange to dark brown. A torus of ionized atoms was discovered along Io's orbital path, which were found to come from erupting volcanoes on the moon's surface. 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'' solar probe. In February 1992, it performed a flyby manoeuvre to attain a
polar orbit A polar orbit is one in which a satellite pass (spaceflight), passes above or nearly above both Poles of astronomical bodies, poles of the body being orbited (usually a planet such as the Earth, but possibly another body such as the Moon or Sun) o ...
around the Sun. During this pass, the spacecraft studied Jupiter's magnetosphere, although it had no cameras to photograph the planet. The spacecraft passed by Jupiter six years later, this time 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 ...
'' 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 is the ninth-largest and tenth-most-massive known object to directly orbit the S ...
. The probe's cameras measured plasma output from volcanoes on Io and studied all four Galilean moons in detail.


''Galileo'' mission

The first spacecraft to orbit Jupiter was the ''
Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
'' mission, which reached the planet on December 7, 1995. It remained in orbit for over seven years, conducting multiple flybys of all the Galilean moons and Amalthea. The spacecraft also witnessed the impact of
Comet Shoemaker–Levy 9 Comet Shoemaker–Levy 9 (Astronomical naming conventions#Comets, formally designated D/1993 F2) broke apart in July 1992 and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of S ...
when it collided with Jupiter in 1994. Some of the goals for the mission were thwarted due to a malfunction in ''Galileos high-gain antenna. A 340-kilogram titanium 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 until the spacecraft was destroyed. 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. NASA destroyed the spacecraft in order to avoid any possibility of the spacecraft crashing into and possibly contaminating the moon Europa, which may harbour 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 vaporized.


''Juno'' mission

NASA's '' Juno'' mission arrived at Jupiter on July 4, 2016 with the goal of studying the planet in detail from a
polar orbit A polar orbit is one in which a satellite pass (spaceflight), passes above or nearly above both Poles of astronomical bodies, poles of the body being orbited (usually a planet such as the Earth, but possibly another body such as the Moon or Sun) o ...
. The spacecraft was originally intended to orbit Jupiter thirty-seven times over a period of twenty months. During the mission, the spacecraft will be exposed to high levels of radiation from Jupiter's magnetosphere, which may cause future failure of certain instruments. 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'' completed 12 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. This will avoid the risk of collision with Jupiter's moons.


Cancelled missions and future plans

There is great interest in missions to study Jupiter's larger icy moons, which may have subsurface liquid oceans. Funding difficulties have delayed progress, causing
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
's '' JIMO'' (''Jupiter Icy Moons Orbiter'') to be 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 Jupiter Ganymede Orbiter (JGO) was a part of the international Europa Jupiter System Mission (EJSM). It was a proposed orbiter by the ESA slated for lift-off in 2020.Cosmic Vision selection. These plans have been realized as the European Space Agency's
Jupiter Icy Moon Explorer The Jupiter Icy Moons Explorer (JUICE) is an interplanetary spacecraft in development by the European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre ...
(JUICE), due to launch in 2023, followed by NASA's ''
Europa Clipper Europa Clipper (previously known as Europa Multiple Flyby Mission) is an interplanetary mission Interplanetary spaceflight or interplanetary travel is the Human spaceflight, crewed or Uncrewed spacecraft, uncrewed travel between stars and p ...
'' mission, scheduled for launch in 2024. Other proposed missions include the Chinese National Space Administration's '' Tianwen-4'' mission which aims to launch an orbiter to the Jovian system and possibly Callisto around 2035, and CNSA's ''
Interstellar Express ''Interstellar Express'' or ''Interstellar Heliosphere Probe'' (), is the current name for a proposed Chinese National Space Administration program designed to explore the heliosphere The heliosphere is the magnetosphere, astrosphere and ...
'' and NASA's ''
Interstellar Probe An interstellar probe is a space probe that has left—or is expected to leave—the Solar System and enter interstellar medium, interstellar space, which is typically defined as the region beyond the Heliopause (astronomy), heliopause. It also r ...
'', which would both use Jupiter's gravity to help them reach the edges of the heliosphere.


Moons

Jupiter has 82 known
natural satellite A natural satellite is, in the most common usage, an astronomical object, astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are often colloquially ref ...
s. Of these, 66 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 Jan ...
", 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 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 neighbours at the same point in every orbit it makes. The
tidal force The tidal force is a gravitational effect that stretches a body along the line towards the center of mass of another body due to a gradient (difference in strength) in gravitational field from the other body; it is responsible for diverse pheno ...
from Jupiter, on the other hand, works to circularise their orbits. The
eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior) Eccentricity (also called quirkiness) is an unusual or odd behavior on the part of an individual. This behavior would typically be perceived as unusual or unnecessary, without ...
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. The
friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding (motion), sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative la ...
created by this tidal flexing generates heat in the interior of the moons. This is seen most dramatically in the
volcanic activity Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the Earth#Surface, surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the su ...
of Io (which is subject to the strongest tidal forces), and to a lesser degree in the geological youth of 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 their similar
orbital elements Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same o ...
. 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 captured asteroids or fragments of captured asteroids. The irregular moons within each group may have a common origin, perhaps as a larger moon or captured body that broke up.


Interaction with the Solar System

As the most massive of the eight planets, the gravitational influence of Jupiter has helped shape the Solar System. With the exception of Mercury, the orbits of the system's planets lie closer to Jupiter's
orbital plane The orbital plane of a revolving body is the plane (geometry), geometric plane in which its orbit lies. Three non-line (geometry), collinear points in space suffice to determine an orbital plane. A common example would be the positions of the ce ...
than the Sun's
equatorial plane The celestial equator is the great circle In mathematics, a great circle or orthodrome is the circle, circular Intersection (geometry), intersection of a sphere and a Plane (geometry), plane incidence (geometry), passing through the sphere's ...
. The
Kirkwood gap A Kirkwood gap is a gap or dip in the distribution of the semi-major axis, semi-major axes (or equivalently of the orbital periods) of the orbits of asteroid belt, main-belt asteroids. They correspond to the locations of orbital resonances with ...
s in the
asteroid belt The asteroid belt is a torus In geometry, a torus (plural tori, colloquially donut or doughnut) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis that is coplanarity, coplanar with the ...
are mostly caused by Jupiter, and the planet may have been responsible for the purported
Late Heavy Bombardment The Late Heavy Bombardment (LHB), or lunar cataclysm, is a hypothesized event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago, at a time corresponding to the Neohadean and Eoarchean eras on Earth. According to the hypothe ...
in the inner Solar System's history. In addition to its moons, Jupiter's gravitational field controls numerous
asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere ...
s that have settled around the
Lagrangian point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the influence of two massive orbit, orbiting bodies. Mathematically, this involves the solutio ...
s that precede and follow the planet in its orbit around the Sun. These are known as the
Trojan asteroid In astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Obj ...
s, and are divided into
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
and
Trojan Trojan or Trojans may refer to: * Of or from the ancient city of Troy * Trojan language, the language of the historical Trojans Arts and entertainment Music * ''Les Troyens'' ('The Trojans'), an opera by Berlioz, premiered part 1863, part 1890 ...
"camps" to honour the ''
Iliad The ''Iliad'' (; grc, Ἰλιάς, Iliás, ; "a poem about Ilium") is one of two major ancient Greek Epic poem, epic poems attributed to Homer. It is one of the oldest extant works of literature still widely read by modern audiences. As with t ...
''. The first of these, 588 Achilles, was discovered by
Max Wolf Maximilian Franz Joseph Cornelius Wolf (21 June 1863 – 3 October 1932) was a German astronomer and a pioneer in the field of astrophotography. He was the chairman of astronomy at the University of Heidelberg and director of the Heidelberg-K ...
in 1906; since then more than two thousand have been discovered. The largest is 624 Hektor. The Jupiter family is defined as comets that have a
semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both focus (geometry), foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major wikt: ...
smaller than Jupiter's; most short-period comets belong to this group. Members of the Jupiter family are thought to form in the
Kuiper belt The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical unit, astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larg ...
outside the orbit of Neptune. During close encounters with Jupiter, they are perturbed into orbits with a smaller period, which then becomes circularised by regular gravitational interaction with the Sun and Jupiter.


Impacts

Jupiter has been called the Solar System's
vacuum cleaner A vacuum cleaner, also known simply as a vacuum or a hoover, is a device that causes suction in order to remove dirt from floors, upholstery, draperies, and other surfaces. It is generally electrically driven. The dirt is collected by either a d ...
because of its immense
gravity well The Hill sphere of an astronomical body is the region in which it dominates the attraction of natural satellite, satellites. To be retained by a planet, a natural satellite, moon must have an orbit that lies within the planet's Hill sphere. Tha ...
and location near the inner Solar System. There are more impacts on Jupiter, such as comets, than on any other planet in the Solar System. For example, Jupiter experiences about 200 times more
asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere ...
and
comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or Coma (cometary), coma, and sometimes also a Comet ta ...
impacts than Earth. In the past, scientists believed that Jupiter partially shielded the inner system from cometary bombardment. However, computer simulations in 2008 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 accretes or ejects them. This topic remains controversial among scientists, as some think it draws comets towards Earth from the
Kuiper belt The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical unit, astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larg ...
, while others believes that Jupiter protects Earth from the
Oort cloud The Oort cloud (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a scientific theory, theoretical concept of a cloud of predominantly volatiles, icy planetesimals proposed to surround the S ...
. In July 1994, the
Comet Shoemaker–Levy 9 Comet Shoemaker–Levy 9 (Astronomical naming conventions#Comets, formally designated D/1993 F2) broke apart in July 1992 and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of S ...
comet collided with Jupiter. The impacts were closely observed by observatories around the world, including the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of ...
and ''Galileo'' spacecraft. The event was widely covered by the media. Surveys of early astronomical records and drawings produced eight examples of potential impact observations between 1664 and 1839. However, a 1997 review determined that these observations had little or no possibility of being the results of impacts. Further investigation by this team revealed a dark surface feature discovered by astronomer
Giovanni Cassini Giovanni Domenico Cassini, also known as Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was an Italian (naturalised French) mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the C ...
in 1690 may have been an impact scar.


In culture

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
Babylon ''Bābili(m)'' * sux, 𒆍𒀭𒊏𒆠 * arc, 𐡁𐡁𐡋 ''Bāḇel'' * syc, ܒܒܠ ''Bāḇel'' * grc-gre, Βαβυλών ''Babylṓn'' * he, בָּבֶל ''Bāvel'' * peo, 𐎲𐎠𐎲𐎡𐎽𐎢 ''Bābiru'' * elx, 𒀸𒁀𒉿𒇷 ''Babi ...
ians, this planet represented their god
Marduk Marduk (Cuneiform: dAMAR.UTU; Sumerian language, Sumerian: ''amar utu.k'' "calf of the sun; solar calf"; ) was a god from ancient Mesopotamia and patron deity of the city of Babylon. When Babylon became the political center of the Euphrates vall ...
, chief of their pantheon from the
Hammurabi Hammurabi (Akkadian language, Akkadian: ; ) was the sixth Amorites, Amorite king of the Old Babylonian Empire, reigning from to BC. He was preceded by his father, Sin-Muballit, who abdicated due to failing health. During his reign, he conque ...
period. They used Jupiter's roughly 12-year orbit along the
ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agai ...
to define the
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellati ...
s of their
zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the Sun path, apparent path of the Sun across the celestial sphere over the course of the year. ...
. The mythical Greek name for this planet is ''
Zeus Zeus or , , ; grc, Δῐός, ''Diós'', label=Genitive case, genitive Aeolic Greek, Boeotian Aeolic and Doric Greek#Laconian, Laconian grc-dor, Δεύς, Deús ; grc, Δέος, ''Déos'', label=Genitive case, genitive el, Δίας, ''D ...
'' (Ζεύς), also referred to as ''Dias'' (Δίας), the planetary name of which is retained in modern
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
. The ancient Greeks knew the planet as
Phaethon Phaethon (; grc, Φαέθων, Phaéthōn, ), also spelled Phaëthon, was the son of the Oceanid Clymene (mother of Phaethon), Clymene and the solar deity, sun-god Helios in Greek mythology. According to most authors, Phaethon is the son of He ...
( grc, Φαέθων, label=none), meaning "shining one" or "blazing star". The Greek myths of Zeus from the
Homer Homer (; grc, Ὅμηρος , ''Hómēros'') (born ) was a Greek poet who is credited as the author of the ''Iliad'' and the ''Odyssey'', two epic poems that are foundational works of ancient Greek literature. Homer is considered one of the ...
ic period showed particular similarities to certain Near-Eastern gods, including the Semitic El and
Baal Baal (), or Baal,; phn, , baʿl; hbo, , baʿal, ). ( ''baʿal'') was a title and honorific meaning "owner", " lord" in the Northwest Semitic languages spoken in the Levant during antiquity. From its use among people, it came to be applie ...
, the Sumerian
Enlil Enlil, , "Lord f theWind" later known as Elil, is an ancient Mesopotamian god associated with wind, air, earth, and storms. He is first attested as the chief deity of the Sumerian pantheon, but he was later worshipped by the Akkadians, B ...
, and the Babylonian god Marduk. The association between the planet and the Greek deity Zeus was drawn from Near Eastern influences and was fully established by the fourth century BCE, as documented in the '' Epinomis'' of
Plato Plato ( ; grc-gre, wikt:Πλάτων, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greeks, Greek philosopher born in Athens during the Classical Greece, Classical period in Ancient Greece. He founded the Platonist school of thou ...
and his contemporaries. The god
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
is the Roman counterpart of Zeus, and he is the principal
god In monotheistic thought, God is usually viewed as the supreme being, creator, and principal object of faith. Swinburne, R.G. "God" in Honderich, Ted. (ed)''The Oxford Companion to Philosophy'', Oxford University Press, 1995. God is typicall ...
of
Roman mythology Roman mythology is the body of myths of ancient Rome In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5t ...
. The Romans originally called Jupiter the "star of Jupiter" (''Iuppiter Stella'')," as they believed it to be sacred to its namesake god. This name comes from the
Proto-Indo-European Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. Its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. No direct record of Proto-Indo-E ...
vocative In grammar In linguistics, the grammar of a natural language is its set of structure, structural constraints on speakers' or writers' composition of clause (linguistics), clauses, phrases, and words. The term can also refer to the study of ...
compound *''Dyēu-pəter'' (nominative: *'' Dyēus-pətēr'', meaning "Father Sky-God", or "Father Day-God"). As the supreme god of the Roman pantheon, Jupiter was the god of thunder, lightning, and storms, and appropriately called the god of light and sky. In
Vedic astrology Jyotisha or Jyotishya (from Sanskrit Sanskrit (; attributively , ; nominalization, nominally , , ) is a classical language belonging to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It arose in South Asia aft ...
, Hindu astrologers named the planet after
Brihaspati Brihaspati ( sa, बृहस्पति, ), also known as Guru, is a Hindu deity Hindu deities are the gods and goddesses in Hinduism. The terms and epithets for deities within the diverse traditions of Hinduism vary, and include Deva ( ...
, the religious teacher of the gods, and often called it "
Guru Guru ( sa, गुरु, International Alphabet of Sanskrit Transliteration, IAST: ''guru;'' Pali'': garu'') is a Sanskrit term for a "mentor, guide, expert, or master" of certain knowledge or field. In pan-Indian religions, Indian traditions, a ...
", which means the "Teacher". In Central Asian Turkic myths, Jupiter is called ''Erendiz'' or ''Erentüz'', from ''eren'' (of uncertain meaning) and ''yultuz'' ("star"). The Turks 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. In China it became known as the "Year-star" (Sui-sing) as Chinese astronomers noted that it jumped one
zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the Sun path, apparent path of the Sun across the celestial sphere over the course of the year. ...
constellation each year (with corrections). In some ancient Chinese writings the years were named, at least in principle, in correlation with the Jovian zodiacal signs.


Gallery

File:Gemini North Infrared View of Jupiter.jpg, Infrared view of Jupiter, imaged by the
Gemini North The Gemini Observatory is an astronomical observatory consisting of two 8.1-metre (26.6 ft) telescopes, Gemini North and Gemini South, which are located at two separate sites in Hawaii and Chile, respectively. The twin Gemini telescopes prov ...
telescope in Hawaiʻi on January 11, 2017 File:Hubble Visible View of Jupiter.jpg, Jupiter imaged in visible light by the Hubble Space Telescope on January 11, 2017 File:Hubble Ultraviolet View of Jupiter.jpg, Ultraviolet view of Jupiter, imaged by Hubble on January 11, 2017 File:Hubble's View of Jupiter and Europa in August 2020.jpg, This image of Jupiter and Europa, taken by Hubble on 25 August 2020, was captured when the planet was 653 million kilometres from Earth. File:Jupiter Showcases Auroras, Hazes (NIRCam Closeup) - 52303461859.png, Infrared photo by
James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, List of the most distant astronomical ...
captured in August 2022


See also

* * * * * *


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
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NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
; 15 July 2021). {{Authority control Articles containing video clips Astronomical objects known since antiquity Gas giants Outer planets