Moons of Jupiter
Many of these moons are identified in groups and called "Jovian Satellites" due to their similar characteristics and close proximity to one another giving the idea that they may have come from the same mold these groups are the Amalthea Group (Metis, Adrastea, Amalthea, and Thebe), Himalia Group (Leda, Himalia, S/ J11, and Lysithea), Pasiphae (Pasiphae, Sinope, Callirrhoe, Megaclite, . The outer eight were named for lovers of Jupiter: Leda, Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae, and Sinope. For the nonGalilean satellites, the "e" ending is reserved for satellites with retrograde orbits; those with normal orbits have names that end in "a.".
Galileo regarded their existence as a fundamental argument in favour of the Copernican model of the solar system what is the definition of ennui in which the planets orbit the Sun. Their orbits around Jupiter were in flagrant violation of the Ptolemaic systemin which all celestial objects must move around Earth. In order of increasing distance from the planet, these satellites are called Io, Europa, Ganymede, and Callisto, for figures closely associated with Jupiter nsmes Greek mythology.
Although approximate diameters and spectroscopic characteristics of namex Galilean moons had been determined from Earth-based observations, it was the Voyager missions that indelibly established these four bodies teh worlds in their own right. The Galileo mission provided a wealth of additional data. This density gradient how to install a pool liner Io to Callisto resembles that found in the solar system itself and seems satellitez result from the same cause see below Origin of the Jovian system.
The density values suggest that Io and Europa have a rocky composition similar to that of the Moonwhereas roughly 50 percent of Ganymede and Callisto must be made of a much less dense substance, water ice being the obvious candidate.
The icy surface of this satellite is so dominated by impact craters sattellites there are no smooth plains like jupited dark maria observed on the Moon. In other words, there seem to be no areas on Callisto where upwelling of material from subsequent internal activity has obliterated any of the record of early bombardment. This record was formed by impacting debris comet nuclei and asteroidal material primarily during the first million thd after the formation of the solar system in much the same way that the craters on the Moon were produced.
The unmodified appearance of the surface is consistent with the absence of a differentiated interior. Evidently no tidally induced global heating and consequent melting occurred on Callisto, unlike the other three Galilean moons. The Galileo spacecraft revealed that craters smaller than 10 km 6 miles are hidden by drifts of fine, dark material resembling a mixture of clay minerals.
In addition to the predominant water ice, solid carbon dioxide is present on the surface, and an extremely tenuous carbon dioxide atmosphere is slowly escaping into space. Other trace surface constituents are hydrogen peroxideprobably whaat from the ice by photochemical reactions driven by solar ultraviolet radiation ; sulfur and sulfur compoundsprobably coming from Io; and organic compounds that may have been delivered by cometary impacts.
Unlike Callisto, Ganymedean equally icy satellite, reveals distinct patches of dark and light terrain. In contrast to the Moon, the dark regions on Ganymede are the older areas, showing the heaviest concentration of craters.
The light regions are younger, revealing a complex pattern of parallel and intersecting ridges and grooves in addition to unusually bright impact craters typically surrounded by systems of rays. This manifestation of active crustal movement and resurfacing is accompanied by clear evidence of internal differentiation.
Unlike Callisto, Ganymede has an iron-rich core and a permanent magnetic field that is strong enough to create its own magnetosphere and jupitwr. Videos Images. Additional Info. Load Previous Page. Montage of Nsmes four Galilean moons— left to right Io, Sre, Ganymede, and Callisto—imaged individually by the Galileo spacecraft, — The images are scaled proportionally and arranged in order of the moons' increasing distance from Jupiter.
Two views of the trailing hemisphere of Jupiter's ice-covered satellite, Europa, as seen by the U. Jupiter's moon Callisto as observed by the Galileo spacecraft in May The bright areas are craters that likely have floors of jupkter. A heavily cratered region near Callisto's equator, in an image taken by the Galileo spacecraft on June 25, North is to the top. The old, double-ringed crater near the centre, named Har, is 50 km 30 miles across. It has a prominent younger crater about 20 km 12 miles across superposed on its western rim, and it is crosscut by streaklike chains of secondary craters formed from material ejected by the impact that produced the large crater partly visible in the upper whhat corner.
Jupiter's satellite Ganymede as observed by the Galileo spacecraft in Wbat darker areas are older than the resurfaced lighter areas. The bright spots are impact craters.
Portion of Ganymede's icy surface showing characteristic dark and light grooved terrain, as recorded by the Galileo spacecraft on May 7, The region in the image is about km miles in its longer how to make bamboo shoot pickle. Visible in the bright areas, which are younger, are lanes of parallel and intersecting ridges and valleys dotted with still brighter impact craters.
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Jupiter Moons. Jupiter has 53 named moons and another 26 awaiting official names. Combined, scientists now think Jupiter has 79 moons. There are many interesting moons orbiting the planet, but the ones of most scientific interest are the first four moons discovered beyond Earth—the Galilean . In order of increasing distance from the planet, these satellites are called Io, Europa, Ganymede, and Callisto, for figures closely associated with Jupiter in Greek mythology. The names were assigned by the German astronomer Simon Marius, Galileo’s contemporary. 80 rows · Sep 08, · Io (Jupiter I) Io is the innermost Galilean moon with the highest density of all Author: Mark Owuor Otieno.
Jupiter was appropriately named by the Romans, who chose to name it after the king of the gods. In addition to being the largest planet in our Solar System — with two and a half times the mass of all the other planets combined — it also has the most moons of any Solar planet. So far, 67 natural satellites have been discovered around the gas giant, and more could be on the way.
The moons of Jupiter are so numerous and so diverse that they are broken down into several groups. First, there are the largest moons known as the Galileans, or Main Group. Beyond them, there are the many Irregular Satellites that circle the planet, along with its debris rings.
Here's what we know about them…. Jupiter's Regular Satellites are so named because they have prograde orbits — i. These orbits are also nearly circular and have a low inclination, meaning they orbit close to Jupiter's equator. Of these, the Galilean Moons aka. These are Jupiter's largest moons, not to mention the Solar System's fourth, sixth, first and third largest satellites, respectively. They contain almost They are also among the most massive objects in the Solar System with the exception of the Sun and the eight planets, with radii larger than any of the dwarf planets.
The names of the moons, which are derived from the lovers of Zeus in Greek mythology, were prescribed by Simon Marius soon after Galileo discovered them in Of these, the innermost is Io, which is named after a priestess of Hera who became Zeus' lover.
With a diameter of 3, kilometers, it is the fourth-largest moon in the Solar System. With over active volcanoes, it is also the most geologically active object in the Solar System.
Its surface is dotted with over mountains, some of which are taller than Earth's Mount Everest. Unlike most satellites in the outer Solar System which are covered with ice , Io is mainly composed of silicate rock surrounding a molten iron or iron sulfide core. Io has an extremely thin atmosphere made up mostly of sulfur dioxide SO2. The second innermost Galilean moon is Europa, which takes its name from the mythical Phoenician noblewoman who was courted by Zeus and became the queen of Crete.
At Europa's surface consists of a layer of water surrounding the mantle which is thought to be kilometers thick. The uppermost section is solid ice while the bottom is believed to be liquid water, which is made warm due to heat energy and tidal flexing.
If true, then it is possible that extraterrestrial life could exist within this subsurface ocean, perhaps near a series of deep-ocean hydrothermal vents. The surface of Europa is also one of the smoothest in the Solar System, a fact which supports the idea of liquid water existing beneath the surface.
The lack of craters on the surface is attributed to the surface being young and tectonically active. Europa is primarily made of silicate rock and likely has an iron core, and a tenuous atmosphere composed primarily of oxygen.
Next up is Ganymede. While it is larger than the planet Mercury, the fact that it is an icy world means that it has only half of Mercury's mass. It is also the only satellite in the Solar System known to possess a magnetosphere, likely created through convection within the liquid iron core. Ganymede is composed primarily of silicate rock and water ice, and a salt-water ocean is believed to exist nearly km below Ganymede's surface — though Europa remains the most likely candidate for this.
Ganymede has a high number of craters, most of which are now covered in ice, and boasts a thin oxygen atmosphere that includes O, O2, and possibly O3 ozone , and some atomic hydrogen.
Callisto is the fourth and farthest Galilean moon. Callisto is named after the daughter of the Arkadian King, Lykaon, and a hunting companion of the goddess Artemis. Composed of approximately equal amounts of rock and ices, it is the least dense of the Galileans, and investigations have revealed that Callisto may also have an interior ocean at depths greater than kilometers from the surface.
Callisto is also one of the most heavily cratered satellites in the Solar System — the greatest of which is the km wide basin known as Valhalla. It is surrounded by an extremely thin atmosphere composed of carbon dioxide and probably molecular oxygen. 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.
The Inner Group or Amalthea group are four small moons that have diameters of less than km, orbit at radii less than , km, and have orbital inclinations of less than half a degree. This groups includes the moons of Metis, Adrastea, Amalthea, and Thebe. Along with a number of as-yet-unseen inner moonlets, these moons replenish and maintain Jupiter's faint ring system — Metis and Adrastea helping Jupiter's main ring, while Amalthea and Thebe maintain their own faint outer rings.
Metis is the closest moon to Jupiter at a distance of , km. It is roughly 40 km in diameter, tidally-locked, and highly-asymmetrical in shape with one of the diameters being almost twice as large as the smallest one.
It was not discovered until the flyby of Jupiter by the Voyager 1 space probe. It was named in after the first wife of Zeus. The second closest moon is Adrastea, which is about , km from Jupiter and 20 km in diameter. Also known as Jupiter XV, Amalthea is the second by distance, and the smallest of the four inner moons of Jupiter. It was discovered in when the Voyager 2 probe photographed it during a flyby. Amalthea, also known as Jupiter V, is the third moon of Jupiter in order of distance from the planet.
It was discovered on September 9, , by Edward Emerson Barnard and named after a nymph in Greek mythology. It is thought to consist of porous water ice with unknown amounts of other materials.
Its surface features include large craters and ridges. Thebe aka. Jupiter XIV is the fourth and final inner moon of Jupiter. It is irregularly shaped and reddish in colour, and is thought like Amalthea to consist of porous water ice with unknown amounts of other materials. Its surface features also include large craters and high mountains — some of which are comparable to the size of the moon itself. The Irregular Satellites are those that are substantially smaller and have more distant and eccentric orbits than the Regular Satellites.
These moons are broken down into families that have similarities in orbit and composition. It is believed that these were at least partially formed as a result of collisions, most likely by asteroids that were captured by Jupiter's gravitational field. Those that are grouped into families are all named after their largest member.
For example, the Himalia group is named after Himalia — a satellite with a mean radius of 85 km, making it the fifth largest moon orbiting Jupiter. It is believed that Himalia was once an asteroid that was captured by Jupiter's gravity, which then experienced a impact that formed the moons of Leda, Lysithea, and Elara.
These moons all have prograde orbits, meaning they orbit in the same direction as Jupiter's rotation. The Carme group takes its name from the Moon of the same name. With a mean radius of 23 km, Carme is the largest member of a family of Jovian satellites which have similar orbits and appearance uniformly red , and are therefore thought to have a common origin. The satellites in this family all have retrograde orbits, meaning they orbit Jupiter in the opposite direction of its rotation.
The Ananke group is named after its largest satellite, which has a mean radius of 14 km. It is believed that Ananke was also an asteroid that was captured by Jupiter's gravity and then suffered a collision which broke off a number of pieces. Those pieces became the other 15 moons in the Ananke group, all of which have retrograde orbits and appear gray in color. The Pasiphae group is a very diverse group which ranges in color from red to grey — signifying the possibility of it being the result of multiple collisions.
Named after Paisphae, which has a mean radius of 30 km, these satellites are retrograde, and are also believed to be the result of an asteroid that was captured by Jupiter and fragmented due to a series of collisions.
There are also several irregular satellites that are not part of any particular family. These include Themisto and Carpo, the innermost and outermost irregular moons, both of which have prograde orbits. After Galileo made the first recorded discovery of the Main Group, no additional satellites were discovered for almost three centuries — not until E. Barnard observed Amalthea in In fact, it was not until the 20th century, and with the aid of telescopic photography and other refinements, that most of the Jovian satellites began to be discovered.
By the time Voyager space probes reached Jupiter around , 13 moons had been discovered, while Voyager herself discovered an additional three — Metis, Adrastea, and Thebe. Between October and February , researchers using sensitive ground-based detectors found and later named another 34 moons, most of which were discovered by a team led by Scott S.
Sheppard and David C. Since , 16 additional moons have been discovered but not yet named, bringing the total number of known moons of Jupiter to Though the Galilean moons were named shortly after their discovery in , the names of Io, Europa, Ganymede and Callisto fell out of favor until the 20th century.
Amalthea aka. Jupiter V was not so named until an unofficial convention took place in , a name that was first used by the French astronomer Camille Flammarion. The other moons, in the majority of astronomical literature, were simply labeled by their Roman numeral i. Jupiter IX until the s. The practice was to name newly discovered moons of Jupiter after lovers and favorites of the god Jupiter Zeus ; and since , also after their descendants.
Given the discovery process, and how long it has taken us, it would not be surprising if there more satellites around Jupiter just waiting to be discovered.
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