query: of the four galilean moons which is the closest to jupiter

pos: Galilean moons disk, in which formation timescales were comparable to or shorter than orbital migration timescales. Io is anhydrous and likely has an interior of rock and metal. Europa is thought to contain 8% ice and water by mass with the remainder rock. These moons are, in increasing order of distance from Jupiter: Io (Jupiter I) is the innermost of the four Galilean moons of Jupiter and, with a diameter of 3642 kilometers, the fourth-largest moon in the Solar System. It was named after Io, a priestess of Hera who became one of the lovers of Zeus. Nevertheless, it was simply referred

pos: Galilean moons thin atmosphere made up mostly of sulfur dioxide (SO). If a surface data or collection vessel were to land on Io in the future, it would have to be extremely tough (similar to the tank-like bodies of the Soviet Venera landers) to survive the radiation and magnetic fields that originate from Jupiter. Europa (Jupiter II), the second of the four Galilean moons, is the second closest to Jupiter and the smallest at 3121.6 kilometers in diameter, which is slightly smaller than the Moon. The name comes from a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the

pos: Jupiter's moons in fiction Jupiter's moons in fiction Jupiter's extensive system of natural satellites – in particular the four large Galilean moons (Io, Europa, Ganymede and Callisto) – has been a common science fiction setting. Some references in fiction focus on more than one moon, or do not refer to a specific moon. Io is the closest of the Galilean satellites to Jupiter. It is almost the same size as the Moon. Because of its position, it is subject to constant tidal flexing and heavy radiation from Jupiter's magnetic field. Since 1979, it has also been known for its abundant volcanism. Europa is the

pos: Jupiter 2000, the "Cassini" probe flew by Jupiter on its way to Saturn, and provided some of the highest-resolution images ever made of the planet. The "New Horizons" probe flew by Jupiter for a gravity assist en route to Pluto. Its closest approach was on February 28, 2007. The probe's cameras measured plasma output from volcanoes on Io and studied all four Galilean moons in detail, as well as making long-distance observations of the outer moons Himalia and Elara. Imaging of the Jovian system began September 4, 2006. The first spacecraft to orbit Jupiter was the "Galileo" probe, which entered orbit

pos: Exploration of Jupiter probe, en route to Pluto, flew by Jupiter for a gravity assist and was the first probe launched directly towards Jupiter since the "Ulysses" in 1990. Its Long Range Reconnaissance Imager (LORRI) took its first photographs of Jupiter on September 4, 2006. The spacecraft began further study of the Jovian system in December 2006, and made its closest approach on February 28, 2007. Although close to Jupiter, "New Horizons" instruments made refined measurements of the orbits of Jupiter's inner moons, particularly Amalthea. The probe's cameras measured volcanoes on Io, studied all four Galilean moons in detail, and made long-distance studies

pos: Galilean moons disk, in which formation timescales were comparable to or shorter than orbital migration timescales. Io is anhydrous and likely has an interior of rock and metal. Europa is thought to contain 8% ice and water by mass with the remainder rock. These moons are, in increasing order of distance from Jupiter: Io (Jupiter I) is the innermost of the four Galilean moons of Jupiter and, with a diameter of 3642 kilometers, the fourth-largest moon in the Solar System. It was named after Io, a priestess of Hera who became one of the lovers of Zeus. Nevertheless, it was simply referred

pos: Galilean moons Galilean moons The Galilean moons are the four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in January 1610, and recognized by him as satellites of Jupiter in March 1610. They were the first objects found to orbit another planet. Their names derive from the lovers of Zeus. They are among the largest objects in the Solar System with the exception of the Sun and the eight planets, with a radius larger than any of the dwarf planets. Ganymede is the largest moon in the Solar System, and is even bigger than the

pos: Galilean moons close to the limit of human visual acuity. Ganymede and Callisto, at their maximum separation, are the likeliest targets for potential naked-eye observation. GIF animation of the resonance of Io, Europa, and Ganymede <br> Galilean moons The Galilean moons are the four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in January 1610, and recognized by him as satellites of Jupiter in March 1610. They were the first objects found to orbit another planet. Their names derive from the lovers of Zeus. They are among the largest objects in the Solar System with

pos: Jupiter Icy Moons Explorer Jupiter Icy Moons Explorer 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 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

pos: Moons of Jupiter J 16, and S/2003 J 23. A number of other moons have only been observed for a year or two, but have decent enough orbits to be easily measurable even in 2018. The first spacecrafts to visit Jupiter were "Pioneer 10" in 1973, and "Pioneer 11" a year later, taking low-resolution images of the four Galilean moons. The "Voyager 1" and "Voyager 2" probes visited Jupiter in 1979, discovering the volcanic activity on Io and the presence of water ice on the surface of Europa. The "Cassini" probe to Saturn flew by Jupiter in 2000 and collected data on interactions

pos: Ganymede (moon) common use until the mid-20th century. In much of the earlier astronomical literature, Ganymede is referred to instead by its Roman numeral designation, (a system introduced by Galileo), in other words "the third satellite of Jupiter". Following the discovery of moons of Saturn, a naming system based on that of Kepler and Marius was used for Jupiter's moons. Ganymede is the only Galilean moon of Jupiter named after a male figure—like Io, Europa, and Callisto, he was a lover of Zeus. Ganymede orbits Jupiter at a distance of 1,070,400 km, third among the Galilean satellites, and completes a revolution every

pos: Galilean moons history. Each generation of moons would have spiraled into Jupiter, due to drag from the disk, with new moons then forming from the new debris captured from the Solar nebula. By the time the present (possibly fifth) generation formed, the disk had thinned out to the point that it no longer greatly interfered with the moons' orbits. The current Galilean moons were still affected, falling into and being partially protected by an orbital resonance which still exists for Io, Europa, and Ganymede. Ganymede's larger mass means that it would have migrated inward at a faster rate than Europa or Io.

pos: Exploration of Io January 8, 1610 is used as the discovery date for the two moons by the International Astronomical Union. Galileo continued to observe the Jupiter system for the next month and a half. On January 13, Galileo observed all four of what would later be known as the Galilean moons of Jupiter for the first time in a single observation, though he had observed all four at various times in the preceding days. On January 15, he observed the motions of three of these satellites, including Io, and came to the conclusions that these objects were not background stars, but were

pos: Galileo Galilei probably bears more of the responsibility for the birth of modern science than anybody else, and Albert Einstein called him the father of modern science. Galileo's astronomical discoveries and investigations into the Copernican theory have led to a lasting legacy which includes the categorisation of the four large moons of Jupiter discovered by Galileo (Io, Europa, Ganymede and Callisto) as the Galilean moons. Other scientific endeavours and principles are named after Galileo including the Galileo spacecraft, the first spacecraft to enter orbit around Jupiter, the proposed Galileo global satellite navigation system, the transformation between inertial systems in classical mechanics denoted

pos: Jupiter Orbiter. However, ESA had formally ended the partnership by April 2011, citing budget issues at NASA and the consequences on the mission timetable. Instead, ESA planned to go ahead with a European-only mission to compete in its L1 Cosmic Vision selection. Jupiter has 79 known natural satellites. Of these, 63 are less than 10 kilometres in diameter and have only been discovered since 1975. The four largest moons, visible from Earth with binoculars on a clear night, known as the "Galilean moons", are Io, Europa, Ganymede, and Callisto. The moons discovered by Galileo—Io, Europa, Ganymede, and Callisto—are among the largest

pos: Io (moon) Io (moon) Io (Jupiter I) is the innermost of the four Galilean moons of the planet Jupiter. It is the fourth-largest moon, has the highest density of all the moons, and has the least amount of water of any known astronomical object in the Solar System. It was discovered in 1610 and was named after the mythological character Io, a priestess of Hera who became one of Zeus' lovers. With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's

pos: Io (moon) green glows in the same image) have also been observed. Io (moon) Io (Jupiter I) is the innermost of the four Galilean moons of the planet Jupiter. It is the fourth-largest moon, has the highest density of all the moons, and has the least amount of water of any known astronomical object in the Solar System. It was discovered in 1610 and was named after the mythological character Io, a priestess of Hera who became one of Zeus' lovers. With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is

pos: Magnetosphere of Jupiter Jovian aurorae and partially for the heating of the thermosphere of Jupiter. Spots were found to correspond to three Galilean moons: Io, Europa and Ganymede. They develop because the co-rotation of the plasma is slowed in the vicinity of moons. The brightest spot belongs to Io, which is the main source of the plasma in the magnetosphere (see above). The Ionian auroral spot is thought to be related to Alfvén currents flowing from the Jovian to Ionian ionosphere. Europa's and Ganymede's spots are much dimmer, because these moons are weak plasma sources, because of sublimation of the water ice from

pos: Moons of Jupiter collision—at some point on a billions of years timescale—likely. Additional tiny moons likely exist but remain undiscovered, as they are very difficult for astronomers to detect. The Galilean moons of Jupiter (Io, Europa, Ganymede, and Callisto) were named by Simon Marius soon after their discovery in 1610. However, these names fell out of favor until the 20th century. The astronomical literature instead simply referred to "Jupiter I", "Jupiter II", etc., or "the first satellite of Jupiter", "Jupiter's second satellite", and so on. The names Io, Europa, Ganymede, and Callisto became popular in the mid-20th century, whereas the rest of the

pos: Exploration of Io in fact, "three stars in the heavens moving about Jupiter, as Venus and Mercury round the Sun." These were the first moons of a planet other than the Earth to be discovered. The discoveries of Io and the other Galilean satellites of Jupiter were published in Galileo's "Sidereus Nuncius" in March 1610. While the Jovian moons he discovered would later be known as the Galilean satellites, after himself, he proposed the name "Medicea Sidera" (Medicean Stars) after his new patrons, the de'Medici family of his native Florence. Initially, he proposed the name "Cosmica Sidera" (Cosmic Stars), after the head of

pos: Magnetosphere of Jupiter and some of these atoms are ionized and brought into co-rotation. This process creates gas and plasma tori in the vicinity of moons' orbits with the Ionian torus being the most prominent. In effect, the Galilean moons (mainly Io) serve as the principal plasma sources in Jupiter's inner and middle magnetosphere. Meanwhile, the energetic particles are largely unaffected by the Alfvén wings and have free access to the moons' surfaces (except Ganymede's). The icy Galilean moons, Europa, Ganymede and Callisto, all generate induced magnetic moments in response to changes in Jupiter's magnetic field. These varying magnetic moments create dipole magnetic

pos: Dwarf planet that are more massive than Eris are the Moon, the four Galilean moons of Jupiter (Io, Europa, Ganymede, and Callisto), one moon of Saturn (Titan), and one moon of Neptune (Triton). The others are six moons of Saturn (Mimas, Enceladus, Tethys, Dione, Rhea, and Iapetus), five moons of Uranus (Miranda, Ariel, Umbriel, Titania, and Oberon), and one moon of Pluto (Charon). There are additional possibilities among TNOs, including Dysnomia orbiting Eris. Alan Stern calls these moons "satellite planets", one of three categories of planet together with dwarf planets and classical planets. The term "planemo" ("planetary-mass object") covers all three. In

pos: Exploration of Jupiter followed by "Voyager 2", which made its closest approach on July 9, 1979, 576,000 km away from the planet's cloud tops. The probe discovered Jupiter's ring, observed intricate vortices in its atmosphere, observed active volcanoes on Io, a process analogous to plate tectonics on Ganymede, and numerous craters on Callisto. The "Voyager" missions vastly improved our understanding of the Galilean moons, and also discovered Jupiter's rings. They also took the first close-up images of the planet's atmosphere, revealing the Great Red Spot as a complex storm moving in a counter-clockwise direction. Other smaller storms and eddies were found throughout the

pos: Solar eclipses on Jupiter to 357" at aphelion. Unlike the near coincidence of the apparent sizes of the Moon and Sun as viewed from Earth, this perspective exaggerates the apparent diameters of all the Galilean moons in comparison to the Sun. Even distant Callisto is over 50% larger, and Io is nearly six times as large. This disparity in angular size makes the moons' shadows on Jupiter more defined than the lunar shadow on Earth during a total solar eclipse, as it narrows the penumbra for a given distance. Solar eclipses on Jupiter Solar eclipses on Jupiter occur when any of the natural satellites

pos: Lucky Starr and the Moons of Jupiter only 23 miles. Part of the novel is also set on Io, the innermost of the Galilean moons. Io is depicted as having a thin atmosphere of methane, and fields of ammonia snow and ice, as well as rivers of liquid ammonia. For six years, Jupiter IX has been the site of a secret project to develop an antigravity, or Agrav, space drive; but the Council of Science learns that information from the project is released to the enemy Sirians. A month after returning from Mercury, protagonists David "Lucky" Starr and John Bigman Jones are sent to Jupiter IX to

pos: Naming of moons Ares (the Greek equivalent of the Roman god Mars). The Galilean moons of Jupiter (Io, Europa, Ganymede and Callisto) were named by Simon Marius soon after their discovery in 1610. However, by the late 19th century these names had fallen out of favor, and for a long time it was most common to refer to them in the astronomical literature simply as "Jupiter I", "Jupiter II", etc., or as "the first satellite of Jupiter", "Jupiter's second satellite", etc. By the first decade of the 20th century, the names Io, Europa, Ganymede, and Callisto had once again recovered popularity, but the

pos: Exploration of Io much higher resolution images. This was important for viewing the geologic features of Jupiter's Galilean moons as well as the cloud features of Jupiter itself. They also had spectrometers with a combined spectral range from the far-ultraviolet to the mid-infrared, useful for examining Io's surface and atmospheric composition and to search for thermal emission sources on its surface. "Voyager 1" was first of the two probes to encounter the Jupiter system in March 1979. On approach to Jupiter in late February and early March 1979, "Voyager" imaging scientists noticed that Io appeared distinct from the other Galilean satellites. Its surface

pos: Galilean moons moons, in contrast, indicates differentiation of their interiors with denser matter at the core and lighter matter above. They also reveal significant alteration of the surface. Ganymede reveals past tectonic movement of the ice surface which required partial melting of subsurface layers. Europa reveals more dynamic and recent movement of this nature, suggesting a thinner ice crust. Finally, Io, the innermost moon, has a sulfur surface, active volcanism and no sign of ice. All this evidence suggests that the nearer a moon is to Jupiter the hotter its interior. The current model is that the moons experience tidal heating as

pos: Galilean moons that their mean density decreases with distance from Jupiter. Callisto, the outermost and least dense of the four, has a density intermediate between ice and rock whereas Io, the innermost and densest moon, has a density intermediate between rock and iron. Callisto has an ancient, heavily cratered and unaltered ice surface and the way it rotates indicates that its density is equally distributed, suggesting that it has no rocky or metallic core but consists of a homogeneous mix of rock and ice. This may well have been the original structure of all the moons. The rotation of the three inner

pos: Moons of Jupiter forming from the new debris captured from the solar nebula. By the time the present (possibly fifth) generation formed, the disk had thinned so that it no longer greatly interfered with the moons' orbits. The current Galilean moons were still affected, falling into and being partially protected by an orbital resonance with each other, which still exists for Io, Europa, and Ganymede. Ganymede's larger mass means that it would have migrated inward at a faster rate than Europa or Io. The outer, irregular moons are thought to have originated from captured asteroids, whereas the protolunar disk was still massive enough

pos: Family Portrait (MESSENGER) the mosaic. From left to right: Venus, Earth, Jupiter, Mars, Mercury, and Saturn. Uranus and Neptune were too small to resolve at this distance (3.0-billion and 4.4-billion kilometers respectively). Careful effort was taken to avoid facing the camera toward the Solar System's central star, the Sun, due to the intense heat at close distance. Several moons are visible in the photo, including the Earth's Moon, and all four Galilean moons: Callisto, Ganymede, Europa, and Io. Additionally, part of the Milky Way is visible between Neptune and Mars. Because "MESSENGER" does not follow the same orbital plane as the Earth, the

pos: Galilean moons to as "Jupiter I", or "The first satellite of Jupiter", until the mid-20th century. With over 400 active volcanos, Io is the most geologically active object in the Solar System. Its surface is dotted with more than 100 mountains, some of which are taller than Earth's Mount Everest. Unlike most satellites in the outer Solar System (which have a thick coating of ice), Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Although not proven, recent data from the Galileo orbiter indicate that Io might have its own magnetic field. Io has an extremely

pos: Io (moon) Io and the other Galilean satellites of Jupiter was published in Galileo's "Sidereus Nuncius" in March 1610. In his "Mundus Jovialis", published in 1614, Simon Marius claimed to have discovered Io and the other moons of Jupiter in 1609, one week before Galileo's discovery. Galileo doubted this claim and dismissed the work of Marius as plagiarism. Regardless, Marius' first recorded observation came from 29 December 1609 in the Julian calendar, which equates to 8 January 1610 in the Gregorian calendar, which Galileo used. Given that Galileo published his work before Marius, Galileo is credited with the discovery. For the next

pos: Name conflicts with minor planets these bodies have exactly the same name, referring to the same mythological character. The earliest such conflicts possibly arose through not considering certain mythological names as "official"; for instance, the names Io, Europa, Ganymede and Callisto for the Galilean satellites of Jupiter were not used in astronomical literature of a certain era, their place being taken by "Jupiter I, Jupiter II, Jupiter III, Jupiter IV" (cf. Naming of moons). In the earliest of these conflicts, the natural satellite was named first, and the conflict arose with the naming of an asteroid. These conflicts span the period 1858-1906. Later conflicts arose

pos: Extraterrestrial skies Galilean satellites would be as bright as the full moon is on Earth; from Io to Callisto their apparent magnitudes would be: −11.2, −9.7, −9.4, and −7.0. Ganymede, the largest moon and third from Jupiter, is almost as bright as Io and Europa, but appears only half the size of Io. However, its great size means that it appears about 2″ larger than Europa. Also, a triple conjunction of Io, Europa and Ganymede would be impossible, because the Laplace resonance that they share prevents this. When two of the Galilean moons are aligned, the third is never less than 90

pos: Galilean moons Galileo: he named them at the suggestion of Johannes Kepler after lovers of the god Zeus (the Greek equivalent of Jupiter): "Io", "Europa", "Ganymede" and "Callisto", in his "Mundus Jovialis", published in 1614. Galileo steadfastly refused to use Marius' names and invented as a result the numbering scheme that is still used nowadays, in parallel with proper moon names. The numbers run from Jupiter outward, thus I, II, III and IV for Io, Europa, Ganymede, and Callisto respectively. Galileo used this system in his notebooks but never actually published it. The numbered names (Jupiter "x") were used until the mid-20th

pos: The Mad Moon The Mad Moon "The Mad Moon" is a science fiction short story by Stanley G. Weinbaum, first published in the December 1935 issue of "Astounding Stories". As did his earlier stories "A Martian Odyssey" and "Parasite Planet", "The Mad Moon" emphasizes Weinbaum's alien ecologies. "The Mad Moon" was the only Weinbaum story set on Io. In Weinbaum's Solar System, Jupiter radiates enough heat to create Earthlike environments on the Galilean moons. Io, the innermost Galilean satellite, has a tropical climate, so that two human settlements are located at the poles, Junopolis in the north and Herapolis in the south. Extending

neg: Callisto (moon) , or "Callistan". Callisto is the outermost of the four Galilean moons of Jupiter. It orbits at a distance of approximately 1 880 000 km (26.3 times the 71 492 km radius of Jupiter itself). This is significantly larger than the orbital radius—1 070 000 km—of the next-closest Galilean satellite, Ganymede. As a result of this relatively distant orbit, Callisto does not participate in the mean-motion resonance—in which the three inner Galilean satellites are locked—and probably never has. Like most other regular planetary moons, Callisto's rotation is locked to be synchronous with its orbit. The length of Callisto's day, simultaneously

neg: Jupiter's moons in fiction smallest of the four Galilean satellites and the second closest to Jupiter. It is theorized to have an ocean of liquid water underneath its icy surface; the thickness of the ice is much debated. The probable presence of the water ocean has made it a favored location for modern fictional speculation about extraterrestrial life in the Solar System. Ganymede is the third of the Galilean moons from Jupiter. It is the largest moon in the Solar System, bigger than the planet Mercury (though less massive), almost 52% larger than the diameter of the Moon and with twice its mass. It

neg: Galilean moons All four Galilean moons are bright enough to be viewed from Earth without a telescope, if only they could appear farther away from Jupiter. (They are, however, easily distinguished with even low-powered binoculars.) They have apparent magnitudes between 4.6 and 5.6 when Jupiter is in opposition with the Sun, and are about one unit of magnitude dimmer when Jupiter is in conjunction. The main difficulty in observing the moons from Earth is their proximity to Jupiter, since they are obscured by its brightness. The maximum angular separations of the moons are between 2 and 10 arcminutes from Jupiter, which is

neg: Moons of Jupiter around Ganymede. In 2016, the "Juno" spacecraft imaged the Galilean moons from above their orbital plane as it approached Jupiter orbit insertion, creating a time-lapse movie of their motion. Moons of Jupiter There are 79 known moons of Jupiter. This gives Jupiter the largest number of moons with reasonably stable orbits of any planet in the Solar System. The most massive of the moons are the four Galilean moons, which were independently discovered in 1610 by Galileo Galilei and Simon Marius and were the first objects found to orbit a body that was neither Earth nor the Sun. From the

neg: Europa (moon) on the icy crust of Europa. The presence of the minerals may have been the result of a collision with an asteroid or comet. Some scientists have speculated that life on Earth could have been blasted into space by asteroid collisions and arrived on the moons of Jupiter in a process called lithopanspermia. Europa (moon) </math></ref> Europa ( ) (Jupiter II) is the smallest of the four Galilean moons orbiting Jupiter, and the sixth-closest to the planet. It is also the sixth-largest moon in the Solar System. Europa was discovered in 1610 by Galileo Galilei and was named after Europa,

neg: Moons of Jupiter Moons of Jupiter There are 79 known moons of Jupiter. This gives Jupiter the largest number of moons with reasonably stable orbits of any planet in the Solar System. The most massive of the moons are the four Galilean moons, which were independently discovered in 1610 by Galileo Galilei and Simon Marius and were the first objects found to orbit a body that was neither Earth nor the Sun. From the end of the 19th century, dozens of much smaller Jovian moons have been discovered and have received the names of lovers or daughters of the Roman god Jupiter or

neg: Europa (moon) Europa (moon) </math></ref> Europa ( ) (Jupiter II) is the smallest of the four Galilean moons orbiting Jupiter, and the sixth-closest to the planet. It is also the sixth-largest moon in the Solar System. Europa was discovered in 1610 by Galileo Galilei and was named after Europa, the mythological mother of King Minos of Crete and lover of Zeus (the Greek equivalent of the Roman god Jupiter). Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and has a water-ice crust and probably an iron–nickel core. It has a very thin atmosphere composed primarily of oxygen. Its

neg: Eclipse have many moons and thus frequently display eclipses. The most striking involve Jupiter, which has four large moons and a low axial tilt, making eclipses more frequent as these bodies pass through the shadow of the larger planet. Transits occur with equal frequency. It is common to see the larger moons casting circular shadows upon Jupiter's cloudtops. The eclipses of the Galilean moons by Jupiter became accurately predictable once their orbital elements were known. During the 1670s, it was discovered that these events were occurring about 17 minutes later than expected when Jupiter was on the far side of the

neg: Moons of Jupiter his Greek equivalent Zeus. The Galilean moons are by far the largest and most massive objects to orbit Jupiter, with the remaining 75 known moons and the rings together comprising just 0.003% of the total orbiting mass.Of Jupiter's moons, eight are regular satellites with prograde and nearly circular orbits that are not greatly inclined with respect to Jupiter's equatorial plane. The Galilean satellites are nearly spherical in shape due to their planetary mass, and so would be considered at least dwarf planets if they were in direct orbit around the Sun. The other four regular satellites are much smaller and

neg: Moons of Jupiter eccentricity) and composition; it is believed that these are at least partially collisional families that were created when larger (but still small) parent bodies were shattered by impacts from asteroids captured by Jupiter's gravitational field. These families bear the names of their largest members. The identification of satellite families is tentative, but the following are typically listed: The moons of Jupiter are listed below by orbital period. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in bold. These are the four Galilean moons, which are comparable in size to the Moon. The other moons

neg: Moons of Jupiter closer to Jupiter; these serve as sources of the dust that makes up Jupiter's rings. The remainder of Jupiter's moons are irregular satellites whose prograde and retrograde orbits are much farther from Jupiter and have high inclinations and eccentricities. These moons were probably captured by Jupiter from solar orbits. Twenty-seven of the irregular satellites have not yet been officially named. The physical and orbital characteristics of the moons vary widely. The four Galileans are all over in diameter; the largest Galilean, Ganymede, is the ninth largest object in the Solar System, after the Sun and seven of the planets, Ganymede

neg: Exploration of Jupiter explore Jupiter was "Pioneer 10", which flew past the planet in December 1973, followed by "Pioneer 11" twelve months later. "Pioneer 10" obtained the first-ever close-up images of Jupiter and its Galilean moons; the spacecraft studied the planet's atmosphere, detected its magnetic field, observed its radiation belts and determined that Jupiter is mainly fluid. "Pioneer 11" made its closest approach, within some 34,000 km of Jupiter's cloud tops, on December 4, 1974. It obtained dramatic images of the Great Red Spot, made the first observation of Jupiter's immense polar regions, and determined the mass of Jupiter's moon Callisto. The information

neg: Ganymede (moon) French astronomer Nicolas-Claude Fabri de Peiresc suggested individual names from the Medici family for the moons, but his proposal was not taken up. Simon Marius, who had originally claimed to have found the Galilean satellites, tried to name the moons the "Saturn of Jupiter", the "Jupiter of Jupiter" (this was Ganymede), the "Venus of Jupiter", and the "Mercury of Jupiter", another nomenclature that never caught on. From a suggestion by Johannes Kepler, Marius once again tried to name the moons: This name and those of the other Galilean satellites fell into disfavor for a considerable time, and were not in

neg: Moons of Jupiter of a score of Galilean-mass satellites that formed early in Jupiter's history. Simulations suggest that, while the disk had a relatively high mass at any given moment, over time a substantial fraction (several tenths of a percent) of the mass of Jupiter captured from the solar nebula was passed through it. However, only 2% of the proto-disk mass of Jupiter is required to explain the existing satellites. Thus there may have been several generations of Galilean-mass satellites in Jupiter's early history. Each generation of moons might have spiraled into Jupiter, because of drag from the disk, with new moons then

neg: Himalia (moon) Himalia (moon) Himalia is the largest irregular satellite of Jupiter. It is the sixth largest Jovian satellite overall in size, and only the four Galilean moons of Jupiter have greater mass. It was discovered by Charles Dillon Perrine at the Lick Observatory on 3 December 1904 and is named after the nymph Himalia, who bore three sons of Zeus (the Greek equivalent of Jupiter). It is one of the largest planetary moons in the Solar System not imaged in detail, and the largest not including the moons of Neptune and several trans-Neptunian objects, particularly Dysnomia, the moon of . Himalia

neg: Himalia (moon) a different moon may have been involved. Himalia (moon) Himalia is the largest irregular satellite of Jupiter. It is the sixth largest Jovian satellite overall in size, and only the four Galilean moons of Jupiter have greater mass. It was discovered by Charles Dillon Perrine at the Lick Observatory on 3 December 1904 and is named after the nymph Himalia, who bore three sons of Zeus (the Greek equivalent of Jupiter). It is one of the largest planetary moons in the Solar System not imaged in detail, and the largest not including the moons of Neptune and several trans-Neptunian objects,

neg: Extraterrestrial skies is 400 thousand times dimmer than sunlight). Because the inner moons of Jupiter are in synchronous rotation around Jupiter, the planet always appears in nearly the same spot in their skies (Jupiter would wiggle a bit because of the non-zero eccentricities). Observers on the sides of the Galilean satellites facing away from the planet would never see Jupiter, for instance. From the moons of Jupiter, solar eclipses caused by the Galilean satellites would be spectacular, because an observer would see the circular shadow of the eclipsing moon travel across Jupiter's face. The sky in the upper reaches of Saturn's atmosphere

neg: Jupiter 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. Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early "Pioneer" and "Voyager"

neg: Technologies in 2001: A Space Odyssey as it traveled towards Jupiter, unless it was changing direction. Proportionally, the Sun, Moon and Earth would not visually line up at the size ratios shown in the opening shot, nor would the Galilean moons of Jupiter align as in the shot just before Bowman enters the Star Gate. Kubrick himself was aware of this latter point. (Due to the perfect Laplace resonance of the orbits of the four large moons of Jupiter, the first three never align, and the third moon, Ganymede, is always exactly 90 degrees away from the other two whenever the two innermost moons are in

neg: Moons of Jupiter of the Galilean moons with Jupiter's extended atmosphere. The "New Horizons" spacecraft flew by Jupiter in 2007 and made improved measurements of its satellites' orbital parameters. The "Galileo" spacecraft was the first to enter orbit around Jupiter, arriving in 1995 and studying it until 2003. During this period, "Galileo" gathered a large amount of information about the Jovian system, making close approaches to all of the Galilean moons and finding evidence for thin atmospheres on three of them, as well as the possibility of liquid water beneath the surfaces of Europa, Ganymede, and Callisto. It also discovered a magnetic field

neg: Mass the Solar System. On 25 August 1609, Galileo Galilei demonstrated his first telescope to a group of Venetian merchants, and in early January 1610, Galileo observed four dim objects near Jupiter, which he mistook for stars. However, after a few days of observation, Galileo realized that these "stars" were in fact orbiting Jupiter. These four objects (later named the Galilean moons in honor of their discoverer) were the first celestial bodies observed to orbit something other than the Earth or Sun. Galileo continued to observe these moons over the next eighteen months, and by the middle of 1611 he had

neg: Galilean moons he was able to see celestial bodies more distinctly than was ever possible before. This allowed Galilei to observe in either December 1609 or January 1610 what came to be known as the Galilean moons. On January 7, 1610, Galileo wrote a letter containing the first mention of Jupiter's moons. At the time, he saw only three of them, and he believed them to be fixed stars near Jupiter. He continued to observe these celestial orbs from January 8 to March 2, 1610. In these observations, he discovered a fourth body, and also observed that the four were not fixed

neg: Jupiter Icy Moons Explorer 1 MeV energy. The Radio & Plasma Wave Investigation ("RPWI") will characterise the plasma environment and radio emissions around the spacecraft, it is composed of four experiments: GANDALF, MIME, FRODO and JENRAGE. "RPWI" will use four Langmuir probes, each one mounted at the end of its own dedicated boom, and sensitive up to 1.6 MHz to characterize plasma and receivers in the frequency range 80 kHz – 45 MHz to measure radio emissions. The Gravity & Geophysics of jupiter and Galilean Moons ("3GM") is a radio science package comprising a Ka transponder and an ultrastable oscillator. "3GM" will be used

neg: Jupiter Xi Zezong has claimed that Gan De, an ancient Chinese astronomer, discovered one of Jupiter's moons in 362 with the unaided eye. If accurate, this would predate Galileo's discovery by nearly two millennia. In his 2nd century work the "Almagest", the Hellenistic astronomer Claudius Ptolemaeus constructed a geocentric planetary model based on deferents and epicycles to explain Jupiter's motion relative to Earth, giving its orbital period around Earth as 4332.38 days, or 11.86 years. In 1610, Italian polymath Galileo Galilei discovered the four largest moons of Jupiter (now known as the Galilean moons) using a telescope; thought to be the

neg: Galilean moons the celatone. The method was used by Cassini and Picard to re-map France. Some models predict that there may have been several generations of Galilean satellites in Jupiter's early history. Each generation of moons to have formed would have spiraled into Jupiter and been destroyed, due to tidal interactions with Jupiter's proto-satellite disk, with new moons forming from the remaining debris. By the time the present generation formed, the gas in the proto-satellite disk had thinned out to the point that it no longer greatly interfered with the moons' orbits. Other models suggest that Galilean satellites formed in a proto-satellite

neg: Jupiter Icy Moons Explorer the Jupiter system in October 2029 after 88 months of travel. By 2033 the spacecraft should enter orbit around Ganymede, after completing various maneuvers around Jupiter and the other moons. Proposed instruments include cameras, spectrometers, magnetometers, and an ice-penetrating radar. The "Jupiter Icy moons Explorer" will perform detailed investigations on Ganymede as a planetary body and evaluate its potential to support life. Investigations of Europa and Callisto will complete a comparative picture of these Galilean moons. The three moons are thought to harbour internal liquid-water oceans, and so are central to understanding the habitability of icy worlds. The main science

neg: Gliese 876 the rare phenomenon of Laplace resonance (a type of resonance first noted in Jupiter's inner three Galilean moons). It is also the first extrasolar system around a normal star with measured coplanarity. Two of the middle planets are located in the system's habitable zone; however, they are giant planets believed to be analogous to Jupiter. Gliese 876 is located fairly close to the Solar System. According to astrometric measurements made by the Hipparcos satellite, the star shows a parallax of 213.28 milliarcseconds, which corresponds to a distance of , currently making it the third-closest known star with orbiting planets, after

neg: Magnetosphere of Jupiter its ring system and the orbits of all four Galilean satellites. Orbiting near the magnetic equator, these bodies serve as sources and sinks of magnetospheric plasma, while energetic particles from the magnetosphere alter their surfaces. The particles sputter off material from the surfaces and create chemical changes via radiolysis. The plasma's co-rotation with the planet means that the plasma preferably interacts with the moons' trailing hemispheres, causing noticeable hemispheric asymmetries. In addition, the large internal magnetic fields of the moons contribute to the Jovian magnetic field. Close to Jupiter, the planet's rings and small moons absorb high-energy particles (energy above

neg: Themisto (moon) (Jupiter) in Greek mythology. Themisto's orbit is unusual: unlike most of Jupiter's moons, which orbit in distinct groups, Themisto orbits alone. The moon is located midway between the Galilean moons and the first group of prograde irregular moons, called the Himalia group. Themisto is about 8 kilometers (5 miles) in diameter (assuming an albedo of 0.04). That figure can be used to find a surface area of between 200 and 380 square kilometers. Themisto (moon) Themisto (; from Greek: "Θεμιστώ"), also known as , is a small prograde irregular satellite of Jupiter. It was discovered in 1975, subsequently lost, and

neg: Exploration of Jupiter considered by the Planetary Decadal Survey to be too expensive. The survey supported a cheaper alternative to JEO. While scientists require further evidence to determine the extent of a rocky core on Jupiter, its Galilean moons provide the potential opportunity for future human exploration. Particular targets are Europa, due to its potential for life, and Callisto, due to its relatively low radiation dose. In 2003, NASA proposed a program called Human Outer Planets Exploration (HOPE) that involved sending astronauts to explore the Galilean moons. NASA has projected a possible attempt some time in the 2040s. In the Vision for Space

neg: Timeline of Galileo (spacecraft) These two actions placed the orbiter on its proper trajectory to tour the Jovian moons. The Jupiter orbit insertion maneuver involved an orbit around the planet, which is referred to as the spacecraft's "zeroth" orbit. The spacecraft's "first," and by far longest, orbit around Jupiter followed the JOI and lasted nearly seven months. On 27 June 1996, this initial orbit culminated in a close encounter with Ganymede, the largest of the four Galilean satellites. After the first Jupiter orbit of seven months, subsequent orbits were much shorter, ranging from one to two and a half months. The orbiter tour included

neg: Sidereus Nuncius In addition, he named his discovered four moons of Jupiter the "Medicean Stars," in honor of the four royal Medici brothers. This helped him receive the position of Chief Mathematician and Philosopher to the Medici at the University of Pisa. Ultimately, his effort at naming the moons failed, for they are now referred to as the "Galilean moons". The reactions to "Sidereus Nuncius", ranging from appraisal and hostility to disbelief, soon spread throughout Italy and England. Many poems and texts were published expressing love for the new form of astronomical science. Three works of art were even created in response

neg: Moons of Jupiter to absorb much of their momentum and thus capture them into orbit. Many are believed to have broken up by mechanical stresses during capture, or afterward by collisions with other small bodies, producing the moons we see today. Some scholars propose that the earliest record of a Jovian moon (Ganymede or Callisto) is a note by Chinese astronomer Gan De of an observation around 364 BC. However, the first certain observations of Jupiter's satellites were those of Galileo Galilei in 1609. By January 1610, he had sighted the four massive Galilean moons with his 30× magnification telescope, and he published

neg: Vittorio Crosten Argenti]], [[Opificio delle pietre dure|Museo dell'Opificio delle Pietre Dure]], [[Palazzo Pitti]] and other Florentine museums. The [[Museo Galileo]] possesses an ebony and ivory frame carved and engraved by Crosten which holds the [[Galileo's objective lens|objective lens]] from the telescope used by [[Galileo Galilei]] in his discovery of the four largest [[Galilean moons|moons of Jupiter]]. The frame is carved with floral motifs, images of scientific instruments and Latin inscriptions commemorating Galileo's achievements and his connection to the Medici family. A [[cartouche]] is inscribed "" ("The sky opened by the lynx-like thought of Galileo with this first glass lens showed stars never

neg: Galilean moons moons the Medician Stars. In his dedicatory introduction, Galileo wrote: Scarcely have the immortal graces of your soul begun to shine forth on earth than bright stars offer themselves in the heavens which, like tongues, will speak of and celebrate your most excellent virtues for all time. Behold, therefore, four stars reserved for your illustrious name ... which ... make their journeys and orbits with a marvelous speed around the star of Jupiter ... like children of the same family ... Indeed, it appears the Maker of the Stars himself, by clear arguments, admonished me to call these new planets

neg: Jupiter usually show Jupiter's four Galilean moons and the prominent cloud belts across Jupiter's atmosphere. A large telescope will show Jupiter's Great Red Spot when it faces Earth. The planet Jupiter has been known since ancient times. It is visible to the naked eye in the night sky and can occasionally be seen in the daytime when the Sun is low. To the Babylonians, this object represented their god Marduk. They used Jupiter's roughly 12-year orbit along the ecliptic to define the constellations of their zodiac. The Romans called it "the star of Jupiter" ("Iuppiter Stella"), as they believed it to

neg: Titan (moon) a similar process to that believed to have formed the planets in the Solar System. As the young gas giants formed, they were surrounded by discs of material that gradually coalesced into moons. Whereas Jupiter possesses four large satellites in highly regular, planet-like orbits, Titan overwhelmingly dominates Saturn's system and possesses a high orbital eccentricity not immediately explained by co-accretion alone. A proposed model for the formation of Titan is that Saturn's system began with a group of moons similar to Jupiter's Galilean satellites, but that they were disrupted by a series of giant impacts, which would go on to

neg: Galilean moons disk, a ring of accreting gas and solid debris analogous to a protoplanetary disk. They may be the remnants of a score of Galilean-mass satellites that formed early in Jupiter's history. Simulations suggest that, while the disk had a relatively high mass at any given moment, over time a substantial fraction (several tenths of a percent) of the mass of Jupiter captured from the Solar nebula was processed through it. However, the disk mass of only 2% that of Jupiter is required to explain the existing satellites. Thus there may have been several generations of Galilean-mass satellites in Jupiter's early

neg: Galilean moons younger, but still ancient, regions with a large array of grooves and ridges. Ganymede has a high number of craters, but many are gone or barely visible due to its icy crust forming over them. The satellite has a thin oxygen atmosphere that includes O, O, and possibly O (ozone), and some atomic hydrogen. Callisto (Jupiter IV) is the fourth and last Galilean moon, and is the second largest of the four, and at 4820.6 kilometers in diameter, it is the third largest moon in the Solar System, and barely smaller than Mercury, though only a third of the latter's

neg: Exploration of Jupiter about the Jovian system, making close approaches to all of the four large Galilean moons and finding evidence for thin atmospheres on three of them, as well as the possibility of liquid water beneath their surfaces. It also discovered a magnetic field around Ganymede. As it approached Jupiter, it also witnessed the impact of Comet Shoemaker–Levy 9. In December 1995, it sent an atmospheric probe into the Jovian atmosphere, so far the only craft to do so. In July 2016, the "Juno" spacecraft, launched in 2011, completed its orbital insertion maneuver successfully, and is now in orbit around Jupiter with

neg: Moons of Jupiter are much smaller, with the least massive Galilean moon being more than 7000 times more massive than the most massive of the other moons. The irregular captured moons are shaded light gray when prograde and dark gray when retrograde. All orbits are based on the estimated orbit on the Julian date 2457000, or 3 September 2017. As several moons of Jupiter are currently lost, these orbital elements may be only rough approximations. As of 2018, seven satellites are considered to be lost. These are S/2003 J 2, S/2003 J 4, S/2003 J 9, S/2003 J 10, S/2003 J 12, S/2003

neg: Io (moon) Telescope. Although Simon Marius is not credited with the sole discovery of the Galilean satellites, his names for the moons were adopted. In his 1614 publication "Mundus Iovialis anno M.DC.IX Detectus Ope Perspicilli Belgici", he proposed several alternative names for the innermost of the large moons of Jupiter, including "The Mercury of Jupiter" and "The First of the Jovian Planets". Based on a suggestion from Johannes Kepler in October 1613, he also devised a naming scheme whereby each moon was named for a lover of the Greek mythological Zeus or his Roman equivalent, Jupiter. He named the innermost large moon

neg: Moons of Saturn astronomers but never seen again. Both moons were said to orbit between Titan and Hyperion. It is thought that the Saturnian system of Titan, mid-sized moons, and rings developed from a set-up closer to the Galilean moons of Jupiter, though the details are unclear. It has been proposed either that a second Titan-sized moon broke up, producing the rings and inner mid-sized moons, or that two large moons fused to form Titan, with the collision scattering icy debris that formed the mid-sized moons. On June 23, 2014, NASA claimed to have strong evidence that nitrogen in the atmosphere of Titan

neg: Provisional designation in astronomy "". Later, once its existence and orbit were confirmed, it received its full designation, "". The Roman numbering system arose with the very first discovery of natural satellites other than Earth's Moon: Galileo referred to the Galilean moons as I through IV (counting from Jupiter outward), in part to spite his rival Simon Marius, who had proposed the names now adopted. Similar numbering schemes naturally arose with the discovery of moons around Saturn and Mars. Although the numbers initially designated the moons in orbital sequence, new discoveries soon failed to conform with this scheme (e.g. "" is Amalthea, which orbits

neg: Sidera Lodoicea the name to honor King Louis XIV of France, who reigned from 1643 to 1715, and who was Cassini's benefactor as patron of the Paris Observatory, of which Cassini was the director. The name was modelled on "Sidera Medicea", "Medicean stars", the Latin name used by Galileo to name the four Galilean satellites of Jupiter, in honor of the Florentine house of Medici. The following contemporary (1686) notice records Cassini's choice of name, and explains his rationale for the same: Sidera Lodoicea Sidera Lodoicea is the name given by the astronomer Giovanni Domenico Cassini to the four moons of Saturn

neg: Sirius four Galilean moons of Jupiter and the rings of Saturn. This has been the subject of controversy and speculation. Doubts have been raised about the validity of Griaule and Dieterlein's work. In a 1991 article in "Current Anthropology" anthropologist Walter van Beek concluded after his research among the Dogon that, "Though they do speak about "sigu tolo" [which is what Griaule claimed the Dogon called Sirius] they disagree completely with each other as to which star is meant; for some it is an invisible star that should rise to announce the "sigu" [festival], for another it is Venus that, through

neg: Galilean moons called Valhalla. Callisto is surrounded by an extremely thin atmosphere composed of carbon dioxide and probably molecular oxygen. Investigation revealed that Callisto may possibly have a subsurface ocean of liquid water at depths less than 300 kilometres. The likely presence of an ocean within Callisto indicates that it can or could harbour life. However, this is less likely than on nearby Europa. Callisto has long been considered the most suitable place for a human base for future exploration of the Jupiter system since it is furthest from the intense radiation of Jupiter. Fluctuations in the orbits of the moons indicate

neg: Galileo's objective lens Galileo's objective lens Galileo's objective lens is a specific objective lens held in the Museo Galileo, Florence, Italy. It was used by Galileo Galilei in the Galilean telescope with which he discovered the four largest moons of Jupiter in 1610. The lens has a diameter of 38mm and a gilt brass housing. The frame is made of ebony and ivory and has dimensions of 410mm x 300mm. In 1677, the Medici commissioned Vittorio Crosten to build the ebony and ivory frame in which the lens has since been preserved. The frame is carved with floral motifs, images of scientific instruments

neg: Galilean moons been considered as a cause. The color of the markings, reddish-brown, is theorized to be caused by sulfur, but scientists cannot confirm that, because no data collection devices have been sent to Europa. Europa is primarily made of silicate rock and likely has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Ganymede (Jupiter III), the third Galilean moon is named after the mythological Ganymede, cupbearer of the Greek gods and Zeus's beloved. Ganymede is the largest natural satellite in the Solar System at 5262.4 kilometers in diameter, which makes it larger than the planet Mercury –

neg: Titan (moon) cycle, at the much lower temperature of about . Titan was discovered on March 25, 1655, by the Dutch astronomer Christiaan Huygens. Huygens was inspired by Galileo's discovery of Jupiter's four largest moons in 1610 and his improvements in telescope technology. Christiaan, with the help of his older brother Constantijn Huygens, Jr., began building telescopes around 1650 and discovered the first observed moon orbiting Saturn with one of the telescopes they built. It was the sixth moon ever discovered, after Earth's Moon and the Galilean moons of Jupiter. Huygens named his discovery "Saturni Luna" (or "Luna Saturni", Latin for "Saturn's

neg: Ganymede (moon) (JUICE), due to launch in 2022. After flybys of all three icy Galilean moons, the probe is planned to enter orbit around Ganymede. Chinese astronomical records report that in 365 BC, Gan De detected what might have been a moon of Jupiter, probably Ganymede, with the naked eye. However, Gan De reported the color of the companion as reddish, which is puzzling since the moons are too faint for their color to be perceived with the naked eye. Shi Shen and Gan De together made fairly accurate observations of the five major planets. On January 7, 1610, Galileo Galilei observed

neg: Ellen Harding Baker resembles illustrations in astronomy books of her period. The quilt shows the sun at the center, the eight planets of our solar system, with indicated orbits around the sun, as well as the asteroid belt. The pattern also indicates the myriad of stars that exist beyond our solar system. Earth's Moon, the Galilean moons of Jupiter, as well as a number of moons for Saturn, Neptune, and Uranus are included, as are Saturn's rings. A comet with its very eccentric orbit is also included, perhaps meant to be Halley's comet, which had last been seen in 1835. The quilt is

neg: Astronomical naming conventions orbit computed, a permanent name is chosen, which replaces the "S/" provisional designation. However, in the past, some satellites remained unnamed for surprisingly long periods after their discovery. See Naming of moons for a history of how some of the major satellites got their current names. The Roman numbering system arose with the very first discovery of natural satellites other than Earth's: Galileo referred to the Galilean moons as I through IV (counting from Jupiter outward), in part to spite his rival Simon Marius, who had proposed the names now adopted, after his own proposal to name the bodies after

neg: Naming of moons were suggested by David L. Rabinowitz of Caltech and refer to the mother goddess and her daughters in Hawaiian mythology. Unlike the planets and dwarf planets, relatively few moons orbiting asteroids have been named. Among them are the following: The Roman numbering system for satellites arose with the very first discovery of natural satellites other than Earth's Moon: Galileo referred to the Galilean moons as I through IV (counting from Jupiter outward), refusing to adopt the names proposed by his rival Simon Marius. Similar numbering schemes naturally arose with the discovery of multiple moons around Saturn, Uranus, and Mars. The

neg: Kepler-90h and pressure, may be able to support liquid water and potentially life. However, such moons do not usually form around planets, they would likely have to be captured from afar; e.g., a protoplanet running astray. A Jupiter-sized planet would likely form moons similar in size to Jupiter's Galilean Moons or Saturn's moon Titan. However, we know that even moons of this size can hold on to atmospheres and have magnetic fields, since Titan has an atmosphere thicker than Earth's and has stable bodies of liquid on its surface. A moon of similar size, Jupiter's Ganymede, has its own magnetic field.

neg: Magnetosphere of Jupiter motion is thought to be responsible for the creation of Jupiter's innermost halo ring (located between 1.4 and 1.71 "R"), which consists of sub-micrometer particles on highly inclined and eccentric orbits. The particles originate in the main ring; however, when they drift toward Jupiter, their orbits are modified by the strong 3:2 Lorentz resonance located at 1.71 "R", which increases their inclinations and eccentricities. Another 2:1 Lorentz resonance at 1.4 Rj defines the inner boundary of the halo ring. All Galilean moons have thin atmospheres with surface pressures in the range 0.01–1 nbar, which in turn support substantial ionospheres with

neg: Europa (moon) century. In much of the earlier astronomical literature, Europa is simply referred to by its Roman numeral designation as "" (a system also introduced by Galileo) or as the "second satellite of Jupiter". In 1892, the discovery of Amalthea, whose orbit lay closer to Jupiter than those of the Galilean moons, pushed Europa to the third position. The "Voyager" probes discovered three more inner satellites in 1979, so Europa is now considered Jupiter's sixth satellite, though it is still sometimes referred to as . Europa orbits Jupiter in just over three and a half days, with an orbital radius of

neg: History of astronomy Jupiter in 1610, which are now collectively known as the Galilean moons, in his honor. This discovery was the first known observation of satellites orbiting another planet. He also found that our Moon had craters and observed, and correctly explained, sunspots, and that Venus exhibited a full set of phases resembling lunar phases. Galileo argued that these facts demonstrated incompatibility with the Ptolemaic model, which could not explain the phenomenon and would even contradict it. With the moons it demonstrated that the earth does not have to have everything orbiting it and that other parts of the solar system could

neg: Redemption Cairn Weinbaum collections: Redemption Cairn "Redemption Cairn" is a science fiction short story by Stanley G. Weinbaum that first appeared in the March 1936 issue of "Astounding Stories". "Redemption Cairn" is the only Weinbaum story set on Europa. In Weinbaum's Solar System, in keeping with the then-current "near-collision" hypothesis of planetary formation, Jupiter radiates enough heat to create Earth-like environments on the Galilean moons. Europa is airless except for a depression on the Jupiter-facing side of the tidally locked moon, which holds a thin, but breathable atmosphere. This region is divided into a number of small valleys separated from each other

neg: Redemption Cairn Redemption Cairn "Redemption Cairn" is a science fiction short story by Stanley G. Weinbaum that first appeared in the March 1936 issue of "Astounding Stories". "Redemption Cairn" is the only Weinbaum story set on Europa. In Weinbaum's Solar System, in keeping with the then-current "near-collision" hypothesis of planetary formation, Jupiter radiates enough heat to create Earth-like environments on the Galilean moons. Europa is airless except for a depression on the Jupiter-facing side of the tidally locked moon, which holds a thin, but breathable atmosphere. This region is divided into a number of small valleys separated from each other by ridges

neg: Exploration of Jupiter its science programme ongoing. The European Space Agency selected the L1-class JUICE mission in 2012 as part of its Cosmic Vision programme to explore three of Jupiter's Galilean moons, with a possible Ganymede lander provided by Roscosmos. JUICE is proposed to be launched in 2022. ISRO will launch the first Indian mission to Jupiter in 2022 or 2023 through Geosynchronous Satellite Launch Vehicle Mark III. Flights from Earth to other planets in the Solar System have a high energy cost. It requires almost the same amount of energy for a spacecraft to reach Jupiter from Earth's orbit as it does

neg: Newton's reflector presented to the Royal Society has a longer focal length as it is significantly longer than the first one shown in his illustration and described in "Opticks". Newton completed his first reflecting telescope in late 1668 and first wrote about it in a February 23, 1669 letter to Henry Oldenburg (Secretary of the Royal Society).". Newton found that he could see the four Galilean moons of Jupiter and the crescent phase of the planet Venus with his new little telescope. Newton's friend Isaac Barrow showed the telescope to small group from the Royal Society of London at the end of

neg: Europa Report Europa Report Europa Report is a 2013 science fiction film directed by Sebastián Cordero, starring Christian Camargo, Anamaria Marinca, Michael Nyqvist, Daniel Wu, Karolina Wydra and Sharlto Copley. A found footage film, it recounts the fictional story of the first crewed mission to Europa, one of the four Galilean moons of Jupiter. Despite a disastrous technical failure that loses all communications with Earth mission control and a series of crises, the crew continues its mission to Europa and finds mounting evidence of life on the moon. Dr. Unger (Embeth Davidtz), CEO of Europa Ventures, narrates the story of the Europa

neg: Jupiter's moons in fiction is 77% the diameter of Mars. Ganymede's size made it a popular location for early science fiction authors looking for locations beyond Mars that might be inhabitable by humans. In reality, Ganymede is a cold, icy, cratered world with a vanishingly thin atmosphere. Callisto is the outermost of the Galilean satellites. It is a large moon, only slightly smaller than the planet Mercury. It is cold, icy, and heavily cratered, with a very tenuous atmosphere. Despite its size and early discovery, it has not been featured in fiction as much as the other Galilean satellites. Amalthea, or Jupiter V, is