The largest satellite of the planet is Jupiter. Ganymede is Jupiter's largest moon. Research of Ganymede in our time and prospects for the colonization of the satellite of Jupiter

A satellite is a dense natural object that orbits a planet. No specific scientific explanation provides a satisfactory answer to the question of how moons came to be, although several theories exist. The Moon was considered the only satellite, but after the invention of the telescope, satellites of others were discovered. Each planet has one or more satellites, except Mercury and Venus. Jupiter has the largest number of satellites - 67. Technological advances have allowed man to discover and even send spacecraft on expeditions to other planets and their satellites.

The largest moons in our solar system are:

Ganymede

Ganymede is the largest moon in our system, orbiting Jupiter. Its diameter is 5,262 km. The moon is larger than Mercury and Pluto, and could easily be called a planet if it were orbiting the Sun. Ganymede has its own magnetic field. Its discovery was made by the Italian astronomer Galileo Galilei on January 7, 1610. The satellite's orbit is about 1,070,400 km from Jupiter and it takes 7.1 Earth days to complete its orbit. The surface of Ganymede has two main types of landscapes. It has lighter and younger regions, as well as a darker crater area. The satellite's atmosphere is thin and contains oxygen in dispersed molecules. Ganymede is primarily composed of water ice and rock, and is believed to have underground oceans. The name of the satellite comes from the name of the prince in ancient greek mythology.

Titanium

Titan is a satellite of Saturn with a diameter of 5,150 km, making it the second largest moon in the Solar System. It was discovered by the Dutch astronomer Christiaan Huygens in 1655. The satellite has a dense atmosphere similar to that of Earth. 90% of the atmosphere consists of nitrogen, and the remaining 10% consists of methane, small amounts of ammonia, argon and ethane. Titan makes a complete revolution around Saturn in 16 days. On the surface of the satellite there are seas and lakes filled with liquid hydrocarbons. This is the only cosmic body in the solar system, besides the Earth, that has water bodies. The name of the satellite is taken from ancient Greek mythology, in honor of the ancient gods called the Titans. Ice and rock make up the bulk of Titan's mass.

Callisto

Callisto is the second largest satellite of Jupiter and the third largest satellite in the Solar System. It has a diameter of 4821 km and is estimated by scientists to be about 4.5 billion years old; its surface is mostly dotted with craters. Callisto was discovered by Galileo Galilei on January 7, 1610. The satellite received its name in honor of a nymph from ancient Greek mythology. Callisto orbits Jupiter at a distance of about 1,882,700 km, and completes its orbit in 16.7 Earth days. It is the most distant moon from Jupiter, meaning it was not significantly exposed to the planet's powerful magnetosphere. Water ice, as well as other materials such as magnesium and hydrated silicates, makes up most mass of the satellite. Callisto has a dark surface and is thought to have a salt sea underneath.

And about

Io is the third largest moon of Jupiter and the fourth in the Solar System. Its diameter is 3,643 km. The satellite was first discovered by Galileo Galilei in 1610. This is the most volcanically active cosmic body along with the Earth. Its surface mainly consists of floodplains of liquid rocks and lava lakes. Io is located approximately 422,000 km from Jupiter, and orbits the planet in 1.77 Earth days. The satellite has spotted look with dominance of white, red, yellow, black and orange flowers. Io's atmosphere is dominated by sulfur dioxide. The moon was named after a nymph from ancient Greek mythology who was seduced by Zeus. Beneath Io's surface is an iron core and an outer layer of silicates.

Other large satellites

Other large satellites of the Solar System include: the Moon (3,475 km), Earth; Europa (3,122 km), Jupiter; Triton (2,707 km), Neptune; Titania (1,578 km), Uranus; Rhea (1,529 km), Saturn and Oberon (1,523 km), Uranus. Most observations of these satellites are made from Earth. Advances in technology make it possible for scientists to send spacecraft to different parts of the solar system to obtain more information about the planets and their satellites.

Table: TOP 10 largest satellites in the solar system

Jupiter can rightfully be called the most “weighty” planet in the solar system, because if you add together all the other planets, including our Earth, then their total mass will be 2.5 times less than that of this giant. Jupiter has very powerful radiation, the level of which in the solar system is exceeded only by the Sun.

Everyone knows the rings of Saturn, but Jupiter also has a lot of satellites. To date, scientists know for sure 67 such satellites, of which 63 are well studied, but it is assumed that Jupiter has at least a hundred satellites, most of which were discovered in recent decades. Judge for yourself: at the end of the 70s of the 20th century, only 13 satellites were registered, and later new generation ground-based telescopes made it possible to detect more than 50 more.

Most of Jupiter's satellites have a small diameter - from 2 to 4 km. Astronomers divide them into Galilean, internal and external.

Galilean satellites

The largest moons of Jupiter: Io, Europa, Ganymede and Callisto were discovered by Galileo Galilei in 1610, and they got their name in honor of him. Their formation occurred after the formation of the planet, from the gas and dust that surrounded it.

And about

Io got her name in honor of Zeus’s beloved, so it would be more correct to talk about her in the feminine gender. It is the fifth satellite of Jupiter and is the most volcanically active body in the Solar System. Io is about the same age as Jupiter itself - 4.5 billion years. Like our Moon, Io is always turned to Jupiter with only one side, and its diameter is not much larger than that of the Moon (3642 km versus 3474 km for the Moon). The distance from Jupiter to Io is 350 thousand km. It is the fourth largest satellite in the solar system.

Volcanic activity is extremely rarely observed on the satellites of planets, and even on the planets of the Solar System themselves. Currently, only four cosmic bodies are known in the Solar System where it manifests itself. This is Earth, Neptune's satellite Triton, Saturn's satellite Enceladus and Io, which among these four is the undisputed leader in terms of volcanic activity.

The scale of the eruptions on Io is such that it is clearly visible from space. Suffice it to say that sulfur magma from volcanoes erupts to a height of up to 300 km (12 such volcanoes have already been discovered), and giant lava flows have covered the entire surface of the satellite, and of a wide variety of colors. And sulfur dioxide predominates in Io’s atmosphere, which is due to high volcanic activity.

Real picture!

Animation of the eruption at Tvashtara Patera, compiled from five images taken by the New Horizons spacecraft in 2007.

Io is quite close to Jupiter (by cosmic standards, of course) and is constantly experiencing the massive effects of its gravity. It is gravity that explains the enormous friction inside Io caused by tidal forces, as well as the constant deformation of the satellite, heating its interior and surface. On some parts of the satellite the temperature reaches 300°C. Along with Jupiter, Io is affected by gravitational forces from two other satellites - Ganymede and Europa, which mainly causes additional heating of Io.

The eruption of Mount Pele on Io, photographed by the Voyager 2 spacecraft.

Unlike volcanoes on Earth, which “sleep” most of the time and erupt only for a fairly short period of time, on hot Io volcanic activity is not interrupted, and peculiar rivers and lakes are formed from the flowing molten magma. The largest molten lake known today has a diameter of 20 km, and contains an island consisting of frozen sulfur.

However, the interaction between the planet and its satellite is not one-way. Although Jupiter, thanks to its powerful magnetic belts, takes up to 1000 kg of matter from Io every second, which almost doubles its magnetosphere. As Io moves through its magnetosphere, it generates electricity so powerful that it upper layers The planet's atmosphere is raging with severe thunderstorms.

Europe

Europe got its name in honor of another lover of Zeus - the daughter of the Phoenician king, whom he kidnapped in the form of a bull. This satellite is the sixth most distant from Jupiter, and is about the same age as it, that is, 4.5 billion years. However, the surface of Europa is much younger (about 100 million years old), so there are practically no meteorite craters on it that arose during the formation of Jupiter and its moons. Only five such craters with a diameter of 10 to 30 km were discovered.

Europa's orbital distance from Jupiter is 670,900 km. The diameter of Europa is smaller than that of Io and the Moon - only 3100 km, and it is also always turned to its planet with one side.

The maximum surface temperature at the equator of Europe is minus 160°C, and at the poles - minus 220°C. Although the entire surface of the satellite is covered with a layer of ice, scientists believe that it hides a liquid ocean. Moreover, researchers believe that some forms of life exist in this ocean thanks to thermal springs located next to underground volcanoes, that is, the same as on Earth. In terms of the amount of water, Europe is twice as large as the Earth.

Two models of the structure of Europe

The surface of Europa is riddled with cracks. The most common hypothesis attributes this to the effects of tidal forces on the ocean shore below the surface. It is likely that the rise of water under the ice above normal occurs as the satellite approaches Jupiter. If this is true, then the appearance of cracks on the surface is precisely caused by the constant rise and fall of the water level.

According to a number of scientists, sometimes the surface breaks through with water masses, like lava during a volcanic eruption, and then these masses freeze. This hypothesis is supported by icebergs that can be seen on the surface of the satellite.

In general, the surface of Europa does not have elevations higher than 100 m, so it is considered one of the smoothest bodies in the Solar System. Europa's thin atmosphere contains mainly molecular oxygen. Apparently, this is explained by the decomposition of ice into hydrogen and oxygen under the influence of solar radiation, as well as other hard radiation. As a result, molecular hydrogen from the surface of Europa quickly evaporates due to its lightness and the weakness of gravity on Europa.

Ganymede

The satellite got its name in honor of the beautiful young man whom Zeus transported to Olympus and made him a cupbearer at the feasts of the gods. Ganymede is the largest moon in the Solar System. Its diameter is 5268 km. If its orbit were not around Jupiter, but around the Sun, it would be considered a planet. The distance between Ganymede and Jupiter is about 1070 million km. It is the only satellite in the solar system that has its own magnetosphere.

About 60% of the satellite is occupied by strange bands of ice, the result of active geological processes that took place 3.5 billion years ago, and 40% is an ancient thick icy crust covered with many craters.

Possible internal structure of Ganymede

Ganymede's core and silicate mantle produce heat that makes the existence of an underground ocean possible. According to scientists, it is located below the surface at a depth of 200 km, while on Europa the large ocean is located closer to the surface.

But the thin layer of Ganymede's atmosphere, consisting of oxygen, is similar to the atmosphere discovered on Europa. Compared to other moons of Jupiter, the flat craters on Ganymede have virtually no elevation and do not have a depression in the center, like craters on the Moon. This appears to be due to the slow, gradual movement of the soft ice surface.

Callisto

The satellite Callisto got its name in honor of another lover of Zeus. With a diameter of 4,820 km, it is the third largest moon in the solar system, with it being approximately 99% of the diameter of Mercury, while the mass of the satellite is three times less than that of the planet.

Callisto, like Jupiter itself and other Galilean satellites, is also about 4.5 billion years old, but its distance to Jupiter compared to other satellites is significantly greater, almost 1.9 million kilometers. Thanks to this, the hard radiation field of the gas giant does not affect it.

The surface of Callisto is one of the oldest surfaces in the solar system - it is about 4 billion years old. Craters cover it all, so over time, each meteorite necessarily fell into an existing crater. There is no violent tectonic activity on Callisto; its surface does not heat up after its formation, so it has retained its ancient appearance.

According to many scientists, Callisto is covered by a thick layer of ice, under which there is an ocean, and the center of the satellite contains rocks and iron. Its thin atmosphere consists of carbon dioxide.

The Valhalla crater with a total diameter of about 3800 km deserves special attention on Callisto. It consists of a bright central region with a diameter of 360 km, surrounded by ridged concentric rings with a radius of up to 1900 kilometers. This whole picture resembles ripples in the water caused by a stone thrown into it, only in this case the role of the “stone” was played by a large asteroid 10-20 km in size. Valhalla is considered the largest formation around an impact crater in the Solar System, although the crater itself is only 13th in size.

Valhalla - impact pool on the moon Callisto

As already mentioned, Callisto is located outside the hard radiation field of Jupiter, so it is considered as the most suitable object (after the Moon and Mars) for constructing a space base. Ice can serve as a source of water, and from Callisto itself it will be convenient to explore another satellite of Jupiter - Europa.

A flight to Callisto will take from 2 to 5 years. The first manned mission is scheduled to launch no earlier than 2040, although the flight could begin later.

Model internal structure Callisto

Shown are an icy crust, a possible water ocean, and a core of rocks and ice.

Inner satellites of Jupiter

Jupiter's inner moons are so named because of their orbits that pass very close to the planet and are within the orbit of Io, which is the closest Galilean moon to Jupiter. There are four inner satellites: Metis, Amalthea, Adrastea and Thebe.

Amalthea, 3D model

Jupiter's faint ring system is replenished and supported not only by its inner satellites, but also by small inner moons that are not yet visible. Jupiter's main ring is supported by Metis and Adrastea, while Amalthea and Thebe have to support their own weak outer rings.

Of all the inner satellites, Amalthea with its dark red surface is of greatest interest. The fact is that there is no analogue to this in the solar system. There is a hypothesis that this surface color is explained by inclusions of minerals and sulfur-containing substances in the ice, but this does not clarify the reason for this color. It is more likely that Jupiter's capture of this satellite occurred from the outside, as regularly happens with comets.

Outer satellites of Jupiter

The outer group consists of small satellites with a diameter of 1 to 170 km, which move in elongated orbits with a strong inclination towards Jupiter's equator. To date, 59 such external satellites are known. Unlike the inner satellites, which move in their own orbits in the direction of Jupiter's rotation, most of the outer satellites move in their orbits in the opposite direction.

Orbits of Jupiter's moons

Since some of the small satellites have almost identical orbits, they are believed to be the remnants of larger satellites destroyed by Jupiter's gravitational force. In photographs taken from spacecraft flying past, they look like shapeless blocks. Apparently, Jupiter's gravitational field captured some of them during their free flight in space.

Rings of Jupiter

Along with its satellites, Jupiter also has its own system, like other gas giants in the Solar System: Saturn, Uranus and Neptune. The rings of Saturn, discovered by Galileo in 1610, look much more spectacular and noticeable, since they consist of shiny ice, but for Jupiter it is just a minor dusty structure. This explains their late discovery, when the Jupiter system was first reached in the 1970s. spaceship.

Galileo's image of the Main Ring using forward-scattered light

Jupiter's ring system consists of four main components:

A halo is a thick torus of particles resembling appearance donut or disk with a hole;

The main ring is very thin and quite bright;

Two outer rings, wide but weak, called “arachnoid rings”.

The halo and Main Ring consist mainly of dust from Metis, Adrastea, and probably several other smaller moons. The halo has a width of approximately 20 to 40 thousand km, although the main component of its mass is located no further than several hundred kilometers from the plane of the ring. The shape of the halo, according to a common hypothesis, is due to the influence of electromagnetic forces inside Jupiter's magnetosphere on dust particles in the ring.

The arachnoid rings are very thin and transparent, like a cobweb, and are named after the material of the satellites of Jupiter, Amalthea and Thebe that form them. The outer edges of the Main Ring are outlined by the satellites Adrastea and Metis.

Jupiter's rings and inner moons

Jupiter is an amazing planet in many ways: The largest planet in the solar system, it has the largest mass, because of this the gravitational force of the planet is simply enormous, this planet, like Saturn, has a distinctive feature -; These are not all the characteristics of Jupiter, but this time I will talk about one of them - its satellite. Jupiter's largest satellite is Ganymede.

Its size allows it to hold 67 satellites in its orbits, but one of the most interesting is Ganymede. Ganymede is not only the largest moon of Jupiter, it is also the largest in the entire solar system. Ganymede is part of the Galilean satellites (the first discovery and observation was made by Galileo Galilei in January 1610 using his first telescope). Ganymede is so large that it is larger than the planet Mercury (Ganymede's diameter is 5,267 km), but Ganymede's mass is about 45% of Mercury's mass.

The largest satellite of Jupiter also differs from all other satellites in that it has its own magnetosphere (magnetic field). Most likely, the magnetic field is caused by convention (a process in which the internal energy of a satellite from the core is transferred by flows to its surface) in the iron-rich core. In addition to the magnetosphere, the satellite also has an atmosphere consisting mainly of atomic oxygen (O), oxygen (O 2) and ozone (O 3). The atmosphere surrounds the satellite in a thin layer and is highly discharged, but, apparently, the satellite is able to hold it due to its gravitational force.

Ganymede and its closest moons

Ganymede, together with Europa and Io, are in orbital resonance; for every revolution of Ganymede around Jupiter, there are 2 revolutions around the planet by the satellite Europa and 4 by Io. Ganymede is very similar to Jupiter's moon Io in its structure - an outer layer of ice, about 800 km. Under this layer of ice, liquid water presumably exists; the water in this ocean may not freeze due to the suitable temperature of the satellite's core.

The largest satellite of Jupiter. Studying

Over the entire period, the largest satellite of Jupiter was visited by 6 spacecraft: Pioneer 10, 11 (in 1973 and 1974, respectively) for the first time received images of Ganymede from close range, Voyager 1, 2 thanks to which the satellite was able to be photographed with higher image quality. Then, the largest satellite of Jupiter was visited by the Galileo spacecraft, which discovered a magnetic field and an ocean on the satellite, under a layer of ice; the last one visited was the New Horizons spacecraft. Now the Juno spacecraft has entered Jupiter orbit, this was done on July 5, 2016. It will explore the origins of Jupiter, its atmosphere and, possibly, the probe will visit several moons, including Ganymede.

Parts of material about satellites, there were only three of them - the Moon near the Earth and two satellites of Mars. Today we are talking about the satellites of just one planet, but the number of satellites the planet has is simply incredible.

Jupiter occupies a special place in the solar system, because it is almost two and a half times larger than all the planets combined. Jupiter is so massive that its common center of mass with the Sun lies above the surface of the Sun.

The common center of mass of Jupiter with the Sun is indicated by a dot

Jupiter has very powerful radiation; in the solar system, only the Sun has a higher level. Compared to other planets, a huge number of satellites revolve around it.

Thanks to ground-based observations of the Jupiter system, thirteen moons were known by the end of the 1970s. In 1979, while flying past Jupiter, the Voyager 1 spacecraft discovered three more satellites. Subsequently, with the help of ground-based telescopes of a new generation, another 51 satellites of Jupiter were discovered.

The vast majority of satellites have a diameter of 2–4 kilometers. Scientists suggest that Jupiter has at least a hundred satellites, but, as already said, 67 have been registered to date, and 63 have been well studied.

The satellites of Jupiter are divided into three groups: Galilean, internal and external. Let's start with the Galilean ones.

Galilean satellites

The four largest satellites - Io, Europa, Ganymede and Callisto - were discovered by Galileo Galilei in 1610, and therefore they are now called “Galileans”. These moons were formed from the gas and dust that surrounded Jupiter after its formation.

Galilean satellites of Jupiter. From left to right, in order of distance from Jupiter: Io, Europa, Ganymede, Callisto

Size comparison. In the top row, from left to right, in order of distance from Jupiter: Io, Europa, Ganymede, Callisto. Below the Earth and Moon

And about

Io, the fifth satellite of Jupiter, is the most volcanically active body in the Solar System. Its age is four and a half billion years; Jupiter is about the same age. The satellite always faces its planet with one side. The distance from the surface of Jupiter to Io is 350 thousand kilometers. Its diameter is 3642 kilometers - slightly larger than that of the Moon (3474 kilometers). It is the fourth largest moon in the Solar System.

Volcanic activity on satellites is an extremely rare phenomenon in the Solar System, and Io in our system is the undoubted favorite in this regard. It is one of the four currently known cosmic bodies in the Solar System that undergo volcanic activity. In addition to it: Earth, Triton (a moon of Neptune) and Enceladus (a moon of Saturn). Venus (the Beta region) is also “suspected” of volcanism, but no active volcanoes have yet been noticed on it.

The eruptions on Io are gigantic and can be clearly seen from space. Volcanoes spew sulfur to a height of three hundred kilometers. On the surface of the satellite, many lava flows and over a hundred calderas are clearly visible, but there are no impact craters; the entire surface is covered with sulfur in various colorful forms. The atmosphere of the moon Io contains mainly sulfur dioxide, this is due to high volcanic activity.

Animation of the eruption at Tvashtara, compiled from five images taken by the New Horizons spacecraft in 2007

Due to its proximity to Jupiter, the satellite is subject to the enormous gravitational forces of the planet, which causes tidal forces that create enormous friction inside the satellite, therefore heating both the interior of Io and its surface occurs. The gravitational forces of the planet constantly stretch and deform the satellite. Some parts of the satellite are heated to three hundred degrees Celsius; Twelve volcanoes have also been discovered on Io, spewing magma to a height of up to three hundred kilometers.

The eruption of Mount Pele on Io, captured by the Voyager 2 spacecraft.

In addition to Jupiter, Io is subject to the gravitational forces of other satellites - Ganymede and Europa. The main influence is exerted by the satellite Europa, providing its additional heating. Unlike terrestrial volcanoes, which have a long period of “sleep” and a relatively short period of eruptions, the volcanoes of the hot satellite are always active. The constantly flowing molten magma forms rivers and lakes. The largest molten lake has a diameter of twenty kilometers and contains an island of frozen sulfur.

Io's movement through Jupiter's magnetosphere generates powerful electricity, causing severe thunderstorms in Jupiter's upper atmosphere. But not only Jupiter feels bad from their interaction - its powerful magnetic belts take 1000 kilograms of substances from Io every second. This further strengthens Jupiter's magnetosphere, effectively doubling its size.

Europe

Europa is the sixth most distant moon from Jupiter. Its surface is covered with a layer of ice, scientists believe that there is a liquid ocean underneath. Europa is about four and a half billion years old - about the same age as Jupiter.

Since the surface of the satellite is young (about one hundred million years), there are almost no meteorite craters on it, which large quantities arose 4.5 billion years ago. Scientists have found only five craters on the surface of Europa, their diameter is 10–30 kilometers.

Europa's orbital distance from Jupiter is 670,900 kilometers. The satellite is always facing the planet with one side, its diameter is 3100 kilometers, therefore, Europa is smaller than the Moon, but larger than Pluto. The surface temperature of Europa at the equator never rises above minus 160 degrees Celsius, and at the poles above minus 220 degrees Celsius.

Two models of the structure of Europe

Scientists theorize that there is an ocean deep beneath the surface of the moon, and that life forms may be found in this ocean. They can exist thanks to thermal springs near underground volcanoes, just like on Earth. The amount of water on Europa is twice as much as on our planet.

Fluctuations in the shape of Europa associated with the tides, causing it to stretch out and then round again

The surface of the satellite is covered with cracks. Many believe it is caused by tidal forces on the ocean below the surface. It's possible that the water beneath the ice rises higher than usual when the moon gets close to Jupiter. And if this is so, then the constant rise and fall of the water level caused many of the cracks observed on the surface. Many scientists believe that the ocean below the surface sometimes breaks through cracks (like lava from a volcano) and then freezes. Icebergs observed on the surface of Europa's moon may be evidence of this theory.

Europa is one of the smoothest bodies in the solar system - there are no elevations of more than a hundred meters on it. The atmosphere on the satellite is rarefied and consists mainly of molecular oxygen. This was probably the result of the decomposition of ice into hydrogen and oxygen under the influence of solar radiation and other hard radiation. Molecular hydrogen quickly evaporates from the surface of the satellite, since it is quite light and Europa's gravitational force is weak.

Ganymede

Ganymede is the largest moon in the Solar System. Its diameter is 5268 kilometers - this is 2% larger than Titan (the second largest satellite in the Solar System) and 8% larger than Mercury. If it had orbited the Sun instead of Jupiter, it would have been classified as a planet. The distance from Ganymede to the surface of Jupiter is approximately 1,070,000 kilometers. It is the only satellite in the Solar System that has its own magnetosphere.

The surface of Ganymede is divided into two groups. The first is strange bands of ice, generated by active geological processes three and a half billion years ago, which occupies 60% of the surface. The second group (the remaining 40% of the surface, respectively) is an ancient thick icy crust covered with numerous craters.

Possible internal structure of Ganymede

The heat that comes from the core and silicate mantle allows the existence of an underground ocean. It is believed to be located two hundred kilometers below the surface, unlike the moon Europa, which has a large ocean closer to the surface.

The moon's atmosphere is thin and composed of oxygen, similar to that found around Europa. The craters on Ganymede have little rise and are very flat compared to craters on other moons. They do not have a central depression, characteristic of craters on the Moon. This is likely due to the slow and gradual movement of the soft ice surface.

Callisto

Callisto is the third largest moon in the Solar System. Its diameter is 4820 km, which is about 99% of the diameter of Mercury, and its mass is only a third of the mass of this planet. Callisto is about 4.5 billion years old, about the same age as Ganymede, Europa, Io, and Jupiter itself. The satellite is located at a distance of almost 1.9 million kilometers (1,882,700 km) from the planet. Due to its large distance from the planet, it is located outside the harsh radiation field of the gas giant.

Callisto

Callisto has one of the oldest surfaces in the solar system - its age is approximately four billion years. It is all covered with craters, and each new meteorite impact certainly fell into an already formed crater. The ancient surface has survived to this day due to the absence of violent tectonic activity and heating of the surface of the satellite since its formation.

Many scientists believe that Callisto is covered with a huge layer of ice, under which there is an ocean, and the center of Callisto contains rocks and iron. Callisto's atmosphere is thin and consists of carbon dioxide.

One of the most remarkable places on Callisto is the Valhalla crater. The crater consists of a bright central region with a diameter of 360 km, around it there are ridges in the form of concentric rings with a radius of up to 1900 kilometers: they radiate from it like the rings of a stone thrown into the water. In total, Valhalla's diameter is about 3,800 kilometers. This is the largest area formed around an impact crater in the entire solar system. The crater itself is only the thirteenth largest in the solar system in size. This structure arose due to the collision of the satellite with a relatively large asteroid 10–20 kilometers in size.

Valhalla - impact pool on the moon Callisto

Since Callisto is located outside the harsh radiation field of Jupiter, it is considered a priority object (after the Moon and Mars) for the construction of a space base. Water can be extracted from the ice of the satellite, and from its surface research can be carried out on another satellite of Jupiter - Europa. The flight to Callisto could take two to five years. It is expected that the first manned mission to this satellite will depart no earlier than 2040, and possibly even later.

Model of the internal structure of Callisto. Shown: icy crust, possible water ocean, and core of rocks and ice

Inner satellites of Jupiter

Why are they internal? The fact is that the orbits of these satellites are located very close to Jupiter and they are all inside the orbit of Io, the closest Galilean satellite to the planet. There are only four of them: Metis, Amalthea, Adrastea and Thebe.

Leading side of Amalthea (Jupiter on the right, north on top). Crater Pan is visible on the upper right edge, Gaia (with bright slopes) on the lower. Color photo Voyager 1 (1979)

Amalthea, 3D model

These moons, as well as a number of as-yet unseen inner moons, replenish and support Jupiter's weak ring system. Metis and Adrastea help support Jupiter's main ring, while Amalthea and Thebe support their own weak outer rings.

Of the satellites of the inner group, Amalthea is of greatest interest. The surface of this satellite has a dark red color, which has no analogues in the Solar System. Scientists suggest that it consists mainly of ice with inclusions of minerals and sulfur-containing substances, but this hypothesis does not explain the color of the satellite. Most likely, Jupiter captured the satellite from the outside, as it regularly does with comets.

Outer satellites of Jupiter

The outer group consists of small satellites whose diameter ranges from one to one hundred and seventy kilometers. They move along elongated orbits strongly inclined towards Jupiter's equator. There are currently 59 outer group satellites. Satellites that are located close to the planet move in their orbits in the direction of Jupiter's rotation, while most distant satellites move in the opposite direction.

Orbits of Jupiter's moons

Some small satellites move in almost identical orbits; it is believed that these are all the remains of larger satellites that were destroyed by the gravitational force of Jupiter. All external satellites that were observed by spacecraft flying past look like shapeless blocks. Most likely, some of them flew freely in space until they were captured by Jupiter's gravitational field.

Rings of Jupiter

In addition to its satellites, Jupiter has a system of rings. Yes, Jupiter also has rings. In addition, all four gas giants in our solar system have them. But unlike Saturn, which has shiny, icy rings, Jupiter's rings have little dusty structure. That is why the rings of Saturn were discovered back in 1610 by Galileo, and the faint rings of Jupiter only in 1970, when a spacecraft first visited the Jupiter system.

Galileo's image of the Main Ring using forward-scattered light

Jupiter's ring system consists of four main components: the "halo" - a thick torus of particles, the relatively bright and very thin "Main Ring", and two broad and faint outer rings known as "spider rings".

The "main ring" and halo consist mainly of dust from Metis, Adrastea and possibly several other satellites. The halo is doughnut-shaped and about twenty to forty thousand kilometers wide, although most of its material lies within a few hundred kilometers of the ring plane. Its shape is believed to be related to electromagnetic forces within Jupiter's magnetosphere acting on ring dust particles.

“Cobweb rings” - rings thin and transparent like a cobweb, named after the material of the satellites that form them: Amalthea and Thebes. The outer edges of the Main Ring are outlined by the moons Adrastea and Metis.

Jupiter's rings and inner moons

We say goodbye to Jupiter and its satellites and continue our journey further. In the next article we will analyze the satellites and rings of Saturn.

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SATELLITES OF PLANETS, relatively massive bodies of natural or artificial origin orbiting planets. 7 of the nine planets in the solar system have natural satellites: Earth (1), Mars (2), Jupiter (16), Saturn (18), Uranus... ... Modern encyclopedia

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• , Asimov Isaac. What to do a thousand miles above Jupiter 9? Build an agrav ship and plan a journey to deadly Jupiter. David "Lucky" Starr, the noble, resourceful space ranger, and his...
• Lucky Starr and the Moons of Jupiter, Isaac Asimov. Three laws of robotics and a fascinating, casual narrative that organically combine scientific facts with fiction from a classic of the SF genre! What to do a thousand miles above Jupiter 9? Build…