Introduction
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two-and-a-half times that of all the other planets in the Solar System combined. Jupiter and Saturn are gas giants; the other two giant planets, Uranus and Neptune, are ice giants. Jupiter has been known to astronomers since antiquity. It is named after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough for its reflected light to cast shadows, and making it on average the third-brightest natural object in the night sky after the Moon and Venus.
Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules. It may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it has a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere. Jupiter has 79 known moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a diameter greater than that of the planet Mercury.
Selected general articles
The Cassini–Huygens mission (/kəˈsiːniˈhɔɪɡənz/ kə-SEE-nee HOY-gənz), commonly called Cassini, was a collaboration between NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a probe to study the planet Saturn and its system, including its rings and natural satellites. The Flagship-class robotic spacecraft comprised both NASA's Cassini probe, and ESA's Huygens lander which landed on Saturn's largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit. The craft were named after astronomers Giovanni Cassini and Christiaan Huygens.
Launched aboard a Titan IVB/Centaur on October 15, 1997, Cassini was active in space for nearly 20 years, with 13 years spent orbiting Saturn, studying the planet and its system after entering orbit on July 1, 2004. The voyage to Saturn included flybys of Venus (April 1998 and July 1999), Earth (August 1999), the asteroid 2685 Masursky, and Jupiter (December 2000). Its mission ended on September 15, 2017, when Cassini's trajectory took it into Saturn's upper atmosphere and it burned up in order to prevent any risk of contaminating Saturn's moons, which might have offered habitable environments to stowaway terrestrial microbes on the spacecraft. The mission is widely perceived to have been successful beyond expectation. Cassini-Huygens has been described by NASA's Planetary Science Division Director as a "mission of firsts", that has revolutionized human understanding of the Saturn system, including its moons and rings, and our understanding of where life might be found in the Solar System.
Cassini's original mission was planned to last for four years, from June 2004 to May 2008. The mission was extended for another two years until September 2010, branded the Cassini Equinox Mission. The mission was extended a second and final time with the Cassini Solstice Mission, lasting another seven years until September 15, 2017, on which date Cassini was de-orbited to burn up in Saturn's upper atmosphere. Read more...
Ganymede /ˈɡænɪmiːd/, a satellite of Jupiter (Jupiter III), is the largest and most massive of the Solar System's moons. The ninth largest object in the Solar System, it is the largest without a substantial atmosphere. It has a diameter of 5,268 km (3,273 mi) and is 8% larger than the planet Mercury, although only 45% as massive. Possessing a metallic core, it has the lowest moment of inertia factor of any solid body in the Solar System and is the only moon known to have a magnetic field. Outward from Jupiter, it is the seventh satellite and the third of the Galilean moons, the first group of objects discovered orbiting another planet. Ganymede orbits Jupiter in roughly seven days and is in a 1:2:4 orbital resonance with the moons Europa and Io, respectively.
Ganymede is composed of approximately equal amounts of silicate rock and water ice. It is a fully differentiated body with an iron-rich, liquid core, and an internal ocean that may contain more water than all of Earth's oceans combined. Its surface is composed of two main types of terrain. Dark regions, saturated with impact craters and dated to four billion years ago, cover about a third of the satellite. Lighter regions, crosscut by extensive grooves and ridges and only slightly less ancient, cover the remainder. The cause of the light terrain's disrupted geology is not fully known, but was likely the result of tectonic activity due to tidal heating.
Ganymede's magnetic field is probably created by convection within its liquid iron core. The meager magnetic field is buried within Jupiter's much larger magnetic field and would show only as a local perturbation of the field lines. The satellite has a thin oxygen atmosphere that includes O, O2, and possibly O3 (ozone). Atomic hydrogen is a minor atmospheric constituent. Whether the satellite has an ionosphere associated with its atmosphere is unresolved. Read more...
The planet Jupiter, the largest planet in the solar system, is a popular backdrop for science fiction stories and films. Early works of science fiction used Jupiter itself as a location for stories, but modern science has shown that the planet has no solid surface one could land on and that its atmosphere, temperature, high gravity and intense radiation is hostile to human life. As a result, the Jovian system as a whole, including both the space around Jupiter and its very extensive system of moons, is a more common setting for science fiction. Read more...
Voyager 1 is a space probe launched by NASA on September 5, 1977. Part of the Voyager program to study the outer Solar System, Voyager 1 was launched 16 days after its twin, Voyager 2. Having operated for 41 years, 7 months and 24 days as of April 29, 2019, the spacecraft still communicates with the Deep Space Network to receive routine commands and to transmit data to Earth. At a distance of 145 AU (21.7 billion km; 13.5 billion mi) from Earth as of February 22, 2019, it is the most distant from Earth of all known man-made objects.
The probe's objectives included flybys of Jupiter, Saturn, and Saturn's largest moon, Titan. While the spacecraft's course could have been altered to include a Pluto encounter by forgoing the Titan flyby, exploration of the moon, which was known to have a substantial atmosphere, took priority. Voyager 1 studied the weather, magnetic fields, and rings of the two planets and was the first probe to provide detailed images of their moons.
After completing its primary mission with the flyby of Saturn on November 12, 1980, Voyager 1 became the third of five artificial objects to achieve the escape velocity required to leave the Solar System. On August 25, 2012, Voyager 1 became the first spacecraft to cross the heliopause and enter the interstellar medium. Read more...
Voyager 2 is a space probe launched by NASA on August 20, 1977, to study the outer planets. Part of the Voyager program, it was launched 16 days before its twin, Voyager 1, on a trajectory that took longer to reach Jupiter and Saturn but enabled further encounters with Uranus and Neptune. It is the only spacecraft to have visited either of these two ice giant planets.
Its primary mission ended with the exploration of the Neptunian system on October 2, 1989, after having visited the Uranian system in 1986, the Saturnian system in 1981, and the Jovian system in 1979. Voyager 2 is now in its extended mission to study the outer reaches of the Solar System and has been operating for 41 years, 8 months and 9 days as of 29 April 2019. It remains in contact through the NASA Deep Space Network.
At a distance of 120 AU (1.80×1010 km) (about 16.5 light-hours) from the Sun as of February 25, 2019, moving at a velocity of 15.341 km/s (55,230 km/h) relative to the Sun, Voyager 2 is the fourth of five spacecraft to achieve the escape velocity that will allow them to leave the Solar System. The probe left the heliosphere for interstellar space on November 5, 2018, becoming the second artificial object to do so, and has begun to provide the first direct measurements of the density and temperature of the interstellar plasma. Read more...- SMARA (SMAll Reconnaissance of Atmospheres) is a swarm of tiny probes weighing less than 1 kilogram which is expected to zip through the clouds of Jupiter by 2030, in conjunction with ESA's JUICE mission, beaming home data about the gas giant's dense atmosphere. According to estimates it could survive for up to 15 minutes in Jupiter's atmosphere and transmit enough information to give scientists a greater understanding of the atmosphere of Jupiter. They will each transmit 20 megabits of data after all. Read more...
The magnetosphere of Jupiter is the cavity created in the solar wind by the planet's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973.
Jupiter's internal magnetic field is generated by electrical currents in the planet's outer core, which is composed of liquid metallic hydrogen. Volcanic eruptions on Jupiter's moon Io eject large amounts of sulfur dioxide gas into space, forming a large torus around the planet. Jupiter's magnetic field forces the torus to rotate with the same angular velocity and direction as the planet. The torus in turn loads the magnetic field with plasma, in the process stretching it into a pancake-like structure called a magnetodisk. In effect, Jupiter's magnetosphere is shaped by Io's plasma and its own rotation, rather than by the solar wind like Earth's magnetosphere. Strong currents in the magnetosphere generate permanent auorae around the planet's poles and intense variable radio emissions, which means that Jupiter can be thought of as a very weak radio pulsar. Jupiter's aurorae have been observed in almost all parts of the electromagnetic spectrum, including infrared, visible, ultraviolet and soft X-rays.
The action of the magnetosphere traps and accelerates particles, producing intense belts of radiation similar to Earth's Van Allen belts, but thousands of times stronger. The interaction of energetic particles with the surfaces of Jupiter's largest moons markedly affects their chemical and physical properties. Those same particles also affect and are affected by the motions of the particles within Jupiter's tenuous planetary ring system. Radiation belts present a significant hazard for spacecraft and potentially to human space travellers. Read more...- A Jupiter-crosser is a minor planet whose orbit crosses that of Jupiter. Jupiter trojans can be inner grazers (105), outer grazers (52), co-orbitals (183), and crossers (537). Discounting them, there is one numbered, 7 non-numbered, and 19 cometary outer-grazers. For the Jupiter trojans, see List of Jupiter trojans (Greek camp) and List of Jupiter trojans (Trojan camp). Read more...
Jupiter (from Latin: Iūpiter [ˈjuːpɪtɛr] or Iuppiter [ˈjʊppɪtɛr], from Proto-Italic *djous "day, sky" + *patēr "father", thus "sky father"), also known as Jove (gen. Iovis [ˈjɔwɪs]), was the god of the sky and thunder and king of the gods in Ancient Roman religion and mythology. Jupiter was the chief deity of Roman state religion throughout the Republican and Imperial eras, until Christianity became the dominant religion of the Empire. In Roman mythology, he negotiates with Numa Pompilius, the second king of Rome, to establish principles of Roman religion such as offering, or sacrifice.
Jupiter is usually thought to have originated as an aerial god. His identifying implement is the thunderbolt and his primary sacred animal is the eagle, which held precedence over other birds in the taking of auspices and became one of the most common symbols of the Roman army (see Aquila). The two emblems were often combined to represent the god in the form of an eagle holding in its claws a thunderbolt, frequently seen on Greek and Roman coins. As the sky-god, he was a divine witness to oaths, the sacred trust on which justice and good government depend. Many of his functions were focused on the Capitoline Hill, where the citadel was located. In the Capitoline Triad, he was the central guardian of the state with Juno and Minerva. His sacred tree was the oak.
The Romans regarded Jupiter as the equivalent of the Greek Zeus, and in Latin literature and Roman art, the myths and iconography of Zeus are adapted under the name Iuppiter. In the Greek-influenced tradition, Jupiter was the brother of Neptune and Pluto, the Roman equivalents of Poseidon and Hades respectively. Each presided over one of the three realms of the universe: sky, the waters, and the underworld. The Italic Diespiter was also a sky god who manifested himself in the daylight, usually identified with Jupiter. Tinia is usually regarded as his Etruscan counterpart. Read more...- The JUpiter ICy moons Explorer (JUICE) is an interplanetary spacecraft in development by the European Space Agency (ESA) with Airbus Defence and Space as the main contractor. The mission is being developed to visit the Jovian system and is focused on studying three of Jupiter's Galilean moons: Ganymede, Callisto, and Europa (excluding the more volcanically active Io) all of which are thought to have significant bodies of liquid water beneath their surfaces, making them potentially habitable environments. The spacecraft is set for launch in June 2022 and would reach Jupiter in October 2029 after five gravity assists and 88 months of travel. By 2033 the spacecraft should enter orbit around Ganymede for its close up science mission and becoming the first spacecraft to orbit a moon other than the moon of Earth. The selection of this mission for the L1 launch slot of ESA's Cosmic Vision science programme was announced on 2 May 2012. Its period of operations will overlap with NASA's Europa Clipper mission, also launching in 2022. Read more...
Comet Shoemaker–Levy 9 (formally designated D/1993 F2) was a comet that broke apart in July 1992 and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects. This generated a large amount of coverage in the popular media, and the comet was closely observed by astronomers worldwide. The collision provided new information about Jupiter and highlighted its possible role in reducing space debris in the inner Solar System.
The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy in 1993. Shoemaker–Levy 9 had been captured by Jupiter and was orbiting the planet at the time. It was located on the night of March 24 in a photograph taken with the 46 cm (18 in) Schmidt telescope at the Palomar Observatory in California. It was the first comet observed to be orbiting a planet, and had probably been captured by Jupiter around 20–30 years earlier.
Calculations showed that its unusual fragmented form was due to a previous closer approach to Jupiter in July 1992. At that time, the orbit of Shoemaker–Levy 9 passed within Jupiter's Roche limit, and Jupiter's tidal forces had acted to pull apart the comet. The comet was later observed as a series of fragments ranging up to 2 km (1.2 mi) in diameter. These fragments collided with Jupiter's southern hemisphere between July 16 and 22, 1994 at a speed of approximately 60 km/s (37 mi/s) (Jupiter's escape velocity) or 216,000 km/h (134,000 mph). The prominent scars from the impacts were more easily visible than the Great Red Spot and persisted for many months. Read more...
Valetudo (/vælɪˈtjuːdoʊ/), also known as Jupiter LXII, is a moon of Jupiter. It was discovered by Scott S. Sheppard and his team in data reaching back to 2016, but was not announced until July 17, 2018, via a Minor Planet Electronic Circular from the Minor Planet Center. It has a diameter of about 1 km (0.6 mi) and orbits Jupiter at a distance of about 19 million kilometres (12 million miles). Its orbital inclination is 34 degrees, and its orbital eccentricity is 0.222. It has a prograde orbit, but it crosses paths with several moons that have retrograde orbits and may in the future collide with them. It was provisionally designated as S/2016 J 2 until it received its name in 2018. The name Valetudo was proposed for it as part of its announcement, after the Roman goddess of health and hygiene, Valetudo, a great-granddaughter of the god Jupiter and approved by the IAU Working Group for Planetary System Nomenclature on 3 October 2018. Read more...
The 2010 Jupiter impact event was a bolide impact event on Jupiter by an object estimated to be about 8–13 meters in diameter. The impactor may have been an asteroid, comet, centaur, extinct comet, or temporary satellite capture. Read more...- A false-color image of the Great Red Spot of Jupiter from Voyager 1. The white oval storm directly below the Great Red Spot has the approximate diameter of Earth.
The Great Red Spot is a persistent high-pressure region in the atmosphere of Jupiter, producing an anticyclonic storm, the largest in the Solar System, 22 degrees south of the planet's equator. It has been continuously observed since 1830. Earlier observations from 1665 to 1713 are believed to be of the same storm; if this is correct, it has existed for at least 350 years. Read more...
The planet Jupiter has a system of rings known as the rings of Jupiter or the Jovian ring system. It was the third ring system to be discovered in the Solar System, after those of Saturn and Uranus. It was first observed in 1979 by the Voyager 1 space probe and thoroughly investigated in the 1990s by the Galileo orbiter. It has also been observed by the Hubble Space Telescope and from Earth for several years. Ground-based observation of the rings requires the largest available telescopes.
The Jovian ring system is faint and consists mainly of dust. It has four main components: a thick inner torus of particles known as the "halo ring"; a relatively bright, exceptionally thin "main ring"; and two wide, thick and faint outer "gossamer rings", named for the moons of whose material they are composed: Amalthea and Thebe.
The main and halo rings consist of dust ejected from the moons Metis, Adrastea, and other unobserved parent bodies as the result of high-velocity impacts. High-resolution images obtained in February and March 2007 by the New Horizons spacecraft revealed a rich fine structure in the main ring. Read more...
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Selected images
Infrared image of Jupiter taken by ESO's Very Large Telescope
This diagram shows the Trojan asteroids in Jupiter's orbit, as well as the main asteroid belt.
Jupiter clouds
(Juno; December 2017)The movement of Jupiter's counter-rotating cloud bands. This looping animation maps the planet's exterior onto a cylindrical projection.
Time-lapse sequence from the approach of Voyager 1, showing the motion of atmospheric bands and circulation of the Great Red Spot. Recorded over 32 days with one photograph taken every 10 hours (once per Jovian day). See full size video.
Jupiter, woodcut from a 1550 edition of Guido Bonatti's Liber Astronomiae
The rings of Jupiter
- Jupiter viewed by the Juno spacecraft
(February 12, 2019) This cut-away illustrates a model of the interior of Jupiter, with a rocky core overlaid by a deep layer of liquid metallic hydrogen.
Jupiter as seen by the space probe Cassini
Perijove 6 pass of Jupiter as viewed by JunoCam Model in the Almagest of the longitudinal motion of Jupiter (☉) relative to Earth (⊕)
Great Red Spot is decreasing in size (May 15, 2014).
Hubble image taken on July 23, 2009, showing a blemish of about 8,000 km (5,000 mi) long left by the 2009 Jupiter impact.
Jupiter's diameter is one order of magnitude smaller (×0.10045) than that of the Sun, and one order of magnitude larger (×10.9733) than that of Earth. The Great Red Spot is roughly the same size as Earth.
Animation of four images showing Jupiter in infrared light as seen by NASA's Infrared telescope facility on May 16, 2015
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