I saw the moons of Jupiter for the first time. Ganymede is the largest moon of Jupiter. Measuring the speed of light

As you know, it is the largest planet in the solar system with the largest mass. For this reason, Jupiter has more moons than any other planet in the solar system. Jupiter is sometimes even called “real star” because he has his own system of cosmic bodies, the center of which he himself is. At the moment, 67 satellites have been registered in orbits of Jupiter, but this is not the most accurate figure. To the question “How many satellites does Jupiter have”, scientists answer that there are at least 100 of them, but not all of them have been discovered yet. The number of satellites studied is only 60. The satellites of the planet Jupiter revolve around the planet both at close distances and at very large ones, thanks to the enormous gravity of the planet.

Satellites of the planet Jupiter or moons of Jupiter.

Usually, the satellites of Jupiter or Jupiter's moons are divided into three groups:

• Galilean
• Internal
• External

Gallie's satellites, as you might guess, were discovered by Galileo back in 1610. These satellites include the most famous satellites of Jupiter: Io, Europa, Callisto, Ganymede. These moons were the first to be discovered because they are the closest to the planet and they are large enough to be detected at that time. Other satellites were discovered a little later. is huge and allows the planet to keep a lot of satellites in its orbits.

And about

This satellite is known for its volcanic activity. Of all the Galilean satellites, it is closest to the planet and, thanks to the same gravity of Jupiter, magma eruptions constantly occur on Io. Magma on Io takes on a range of colors, from yellow to brown and sometimes even black. The surface of Io is solid, unlike, and it is covered with its own solidified magma, so the color of the satellite's surface is mostly yellow.

Europe

Europe is even more interesting object. It has an interesting relief which consists of ice and unusual cracks in it. Scientists have been “puzzling over” the question of the origin of such a relief for quite a long time. All the cracks in the huge block of ice that covers the satellite form a grid that spreads over the entire surface of Europa. There is an assumption that under this ice, closer to the core of the satellite, there is an ocean in which, perhaps, there is life.

Callisto

The second largest moon in the Jupiter system. The surface of this satellite is completely covered with craters from various cosmic bodies hitting the satellite. This fact indicates that Callisto is older than the other satellites and also that there is no volcanic activity on Callisto.

Ganymede

The largest moon in the Jupiter system. The surface of Ganymede, like Europa, is covered with a thick layer of ice and has an active molten metal core in its depths, which creates its own magnetic field for Ganymede. Presumably, closer to the core of the satellite, where the temperature allows the existence of water, there is an ocean in which life can exist. If Ganymede was not a satellite of Jupiter, it could be safely attributed to an independent planet.

There are also small satellites that rotate very close to the planet and are called internal. Here one could talk about 56 more studied satellites of Jupiter, but so far little is known about them. have their own mechanics of rotation around the planet, which is presented in the animation below.

Parts of the 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 only one planet, but the number of satellites on the planet 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 their 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 a very powerful radiation, in the solar system the level is higher only in the sun. Compared to other planets, a huge number of satellites revolve around it.

By the end of the 1970s, thirteen satellites were known from ground-based observations of the Jupiter system. In 1979, during a flyby of Jupiter, the Voyager 1 spacecraft discovered three more moons. Later, 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 mentioned, 67 have been registered to date, and 63 have been well studied.

The moons of Jupiter are divided into three groups: Galilean, inner and outer. Let's start with Galilean.

Galilean satellites

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

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

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

And about

Io is the fifth moon of Jupiter and is the most volcanic active body in the solar system. Its age is four and a half billion years; about the same age as Jupiter. The satellite is always turned to its planet on one side. The distance from the surface of Jupiter to Io is 350,000 kilometers. Its diameter is 3642 kilometers - slightly larger than that of the Moon (3474 kilometers). It is the fourth largest satellite 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 indicator. It is one of the four currently known cosmic bodies of the solar system, on which processes of volcanic activity are taking place. In addition to him: Earth, Triton (satellite of Neptune) and Enceladus (saturn satellite). Venus (the Beta region) is also “suspected” of volcanism, but so far no active volcanoes have 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 gray in various colorful forms. The atmosphere of the moon Io contains mainly sulfur dioxide, this is due to high volcanic activity.

Animation of an eruption in the Tvashtar pater, compiled from five images taken by the New Horizons spacecraft in 2007

Due to the proximity to Jupiter, the huge gravitational forces of the planet act on the satellite, which causes tidal forces that create huge friction inside the satellite, so both the bowels of Io and its surface are heated. The gravitational forces of the planet are constantly pulling and deforming the satellite. Some parts of the satellite are heated up to three hundred degrees Celsius; also on Io, twelve volcanoes were discovered, spewing magma to a height of up to three hundred kilometers.

Pele volcano eruption on Io, taken by the Voyager 2 spacecraft

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

Io's movement through Jupiter's magnetosphere generates powerful electricity, causing violent thunderstorms in Jupiter's upper atmosphere. But not only Jupiter is 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 moon from Jupiter. Its surface is covered with a layer of ice, scientists believe that under it there is a liquid ocean. 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 a hundred million years), there are almost no meteorite craters on it, which in in large numbers emerged 4.5 billion years ago. Scientists have found only five craters on the surface of Europa, their diameter is 10-30 kilometers.

The orbital distance of Europa from Jupiter is 670,900 kilometers. The satellite is turned to the planet all the time on one side, its diameter is 3100 kilometers, therefore, Europe 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 speculate that an ocean exists deep below the surface of the moon, and that life forms can be found in this ocean. They can exist due to thermal springs near underground volcanoes, just like on Earth. The amount of water on Europe is twice as much as on our planet.

Fluctuations in the shape of Europa, associated with the tides, forcing it to stretch out, 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 is possible that the water under the ice rises higher than normal as the moon comes close to Jupiter. And if so, then the constant rise and fall of the water level has caused many of the cracks observed on the surface. Many scientists believe that the ocean beneath the surface sometimes bursts 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 hills 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 escapes 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 - it is 2% more than that of Titan (the second largest satellite in the solar system) and 8% more than that of Mercury. If it orbited the Sun instead of Jupiter, it would be 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 with 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 occupy 60% of the surface. The second group (the remaining 40% of the surface, respectively) is an ancient thick ice crust covered with numerous craters.

Possible internal structure of Ganymede

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

The moon's atmosphere is thin and composed of oxygen, similar to that found near Europa. The craters on Ganymede are almost non-erect and very flat compared to craters on other moons. They do not have a central depression, characteristic of craters on the Moon. This is probably 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 removed from the planet at a distance of almost 1.9 million kilometers (1,882,700 km). Due to its great distance from the planet, it is outside the hard 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 impact of a meteorite will certainly fall 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 satellite's surface since its formation.

Many scientists believe that Callisto is covered by a huge layer of ice, under which the ocean is located, and the center of Callisto contains rocks and iron. The atmosphere of Callisto is rarefied 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 are ridges in the form of concentric rings with a radius of up to 1900 kilometers: they diverge from it like rings from a stone thrown into the water. In general, the diameter of Valhalla is about 3800 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. Such a structure arose due to the collision of the satellite with a relatively large asteroid 10–20 kilometers in size.

Valhalla - an impact basin on the moon Callisto

Since Callisto is outside the harsh radiation field of Jupiter, it is considered as a priority object (after the Moon and Mars) for the construction of a space base. Water can be extracted from the moon's ice, and from its surface, another moon of Jupiter, Europa, can be explored. A flight to Callisto can take two to five years. It is assumed that the first manned mission to this satellite will depart no earlier than 2040, and possibly even later.

Model internal structure Callisto. Shown: ice crust, possible water ocean, and rock and ice core

Jupiter's inner moons

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

The leading side of Amalthea (Jupiter on the right, north on top). The 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 small inner moons, supplement and support Jupiter's weak ring system. Metis and Adrastea help support Jupiter's main ring, while Amalthea and Thebe maintain their own weak outer rings.

Of the satellites of the inner group, Amalthea is of the 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 does regularly with comets.

Jupiter's outer moons

The outer group consists of small satellites, the diameter of which is from one to one hundred and seventy kilometers. They move along elongated and strongly inclined orbits to Jupiter's equator. There are currently 59 satellites of the outer group. Satellites that are 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 all these are the remnants of larger satellites that were destroyed by Jupiter's gravitational force. All external satellites, which were observed by spacecraft flying by, outwardly resemble shapeless blocks. Most likely, some of them flew freely in space until they were captured by the gravitational field of Jupiter.

Rings of Jupiter

In addition to 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 a slight dusty texture. That is why the rings of Saturn were discovered back in 1610 by Galileo, and the faint rings of Jupiter only in the 1970s, when spaceship first visited the Jupiter system.

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

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

The "main ring" and halo are mostly dust from Metis, Adrastea, and possibly a few other moons. The halo is donut-shaped and about twenty to forty thousand kilometers wide, although most of its material lies within a few hundred kilometers of the plane of the ring. Its shape is thought to be due to the electromagnetic forces within Jupiter's magnetosphere acting on dust particles in the ring.

"Spider rings" - rings thin and transparent like a web, are called by the material of the satellites that form them: Amalthea and Thebes. The outer edges of the Main Ring are outlined by the satellites 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.

Some of these moons still remain a mystery to astronomers, because the human foot has not yet set foot everywhere, but somewhere the existence of living organisms is quite possible! But what we know for sure is at least their size. In this list, you will get to know the 10 largest planetary satellites in our solar system.

10. Oberon, satellite of Uranus (average diameter - 1523 kilometers)

Oberon, also known as Uranus IV, is the most distant satellite from the center of Uranus, the second largest satellite of this planet and the ninth largest among all known satellites of our solar system. Discovered in 1787 by explorer William Herschel, Oberon is named after the mythical king of the elves and fairies mentioned in Shakespeare's A Midsummer Night's Dream. Oberon's orbit lies partly outside the magnetosphere of Uranus.

9. Rhea, satellite of Saturn (average diameter - 1529 kilometers)

Rhea is the second largest moon of Saturn and the ninth largest satellite in the entire solar system. At the same time, it is the second smallest cosmic body in our solar system, second only to the asteroid and dwarf planet Ceres in this ranking. Rhea received this status for confirmed data that she has hydrostatic balance. Discovered in 1672 by Giovanni Cassini.

8. Titania, satellite of Uranus (average diameter - 1578 kilometers)

It is the largest moon of Uranus and the eighth largest in the solar system. Discovered in 1787 by William Herschel, Titania was named after the fairy goddess in Shakespeare's A Midsummer Night's Dream. Titania's orbit does not go beyond the magnetosphere of Uranus.

7. Triton, satellite of Neptune (average diameter - 2707 kilometers)

Triton is the largest moon of the planet Neptune, discovered on October 10, 1846 by the English astronomer William Lassell. It is the only large moon with a retrograde orbit in our solar system. Triton moves in the opposite direction to the rotation of its planet. At 2,707 kilometers in diameter, Triton is considered the seventh largest moon in the solar system. There was a time when Triton was considered a dwarf planet from the Kuiper asteroid belt due to properties similar to Pluto - retrograde and composition.

6. Europa, satellite of Jupiter (average diameter - 3122 kilometers)

It is the smallest of the Galilean moons orbiting Jupiter and the sixth closest to its planet. It is also the sixth largest satellite in the solar system. Galileo Galilei discovered Europa in 1610 and named this celestial body in honor of the legendary mother of the Cretan King Minos and mistress of Zeus.

5. Moon, satellite of the Earth (average diameter - 3475 kilometers)

Our Moon is believed to have formed 4.5 billion years ago shortly after the formation of the Earth itself. There are several hypotheses about its origin. The most common among them says that the Moon was formed from fragments after the collision of the Earth with the cosmic body Thei, comparable in size to Mars.

4. Io, satellite of Jupiter (average diameter - 3643 kilometers)

Io is the most geologically active celestial object in our solar system, and has earned this title for at least 400 active volcanoes. The reason for this extreme activity is the heating of the interior of the satellite due to tidal friction caused by the gravitational influence of Jupiter and other Galilean satellites (Europa, Ganymede and Callisto).

3. Callisto, satellite of Jupiter (average diameter - 4821 kilometers)

Galileo Galilei discovered Callisto, like some of Jupiter's other moons, in 1610. With impressive dimensions, this satellite is 99% of the diameter of Mercury, but only a third of its mass. Callisto is the fourth Galilean satellite of Jupiter in terms of distance from the center of the planet, with an orbital radius of 1,883,000 kilometers.

2. Titan, satellite of Saturn (average diameter - 5150 kilometers)

It is the sixth ellipsoidal satellite of Saturn. Very often it is called a planet-like satellite, because the diameter of Titan is 50% larger than the diameter of our moon. In addition, it is 80% heavier than the satellite of our Earth.

1. Ganymede, satellite of Jupiter (average diameter - 5262 kilometers)

Ganymede is equally composed of silicate rocks and frozen water. It is a fully differentiated celestial body, rich in iron, with a liquid core and an outer ocean that may contain more water than over the entire Earth in the sum of all its oceans. The surface of Ganymede is distinguished by two types of relief. The dark regions of the satellite are saturated with craters from asteroid impacts, which occurred presumably 4 billion years ago. This landform covers about a third of the moon.

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 they total weight will be 2.5 times less than that of this giant. Jupiter has a very powerful radiation, the level of which in the solar system exceeds only the Sun.

Everyone knows the rings of Saturn, but Jupiter also has a lot of satellites. To date, scientists know exactly 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.

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

Galilean satellites

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

And about

Io got her name in honor of the beloved Zeus, so it would be more correct to speak of her in the feminine gender. It is the fifth moon of Jupiter and is the most volcanically active body in the solar system. Io is about the same age as Jupiter itself, at 4.5 billion years old. Like our Moon, Io is always turned to Jupiter with only one side, and its diameter is slightly larger than the lunar one (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.

On the satellites of the planets, and on the planets of the solar system themselves, volcanic activity is extremely rarely observed. Currently, only four cosmic bodies are known in the solar system, where it manifests itself. This is the Earth, Neptune's satellite Triton, Saturn's satellite Enceladus and Io, which in this 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 sulfuric magma from volcanoes erupts to a height of up to 300 km (12 such volcanoes have already been discovered), and giant lava flows covered the entire surface of the satellite, and of a wide variety of colors. Yes, and in the atmosphere of Io, sulfur dioxide prevails, due to high volcanic activity.

Real picture!

Animation of the eruption in the Tvashtar pater, compiled from five images taken by the New Horizons spacecraft in 2007.

Io is quite close to Jupiter (by cosmic standards, of course) and constantly experiences the massive effect of its gravity. It is gravity that explains the huge 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 gravity from two other satellites - Ganymede and Europa, which basically causes additional heating of Io.

The Pele volcano eruption on Io, taken by the Voyager 2 spacecraft.

Unlike volcanoes on Earth, which most time they "sleep" 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 it contains an island consisting of solidified sulfur.

However, the interaction of 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. Due to the movement of Io through its magnetosphere, electricity is generated so powerful that in upper layers The atmosphere of the planet is raging with the strongest thunderstorms.

Europe

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

The orbital distance of Europa from Jupiter is 670,900 km. The diameter of Europe is less than that of Io and the Moon - only 3100 km, and it is also always turned to its planet on 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 in this ocean there are some forms of life due to thermal springs located near underground volcanoes, that is, just like on Earth. In terms of the amount of water, Europe is two times ahead of the Earth.

Two Models of the Structure of Europe

The surface of Europa is dotted with cracks. The most common hypothesis explains this as the effect of tidal forces on the ocean below the surface. It is likely that the rise of water under the ice above normal occurs when the satellite approaches Jupiter. If this is true, then the appearance of cracks on the surface is precisely caused by constant rises and falls in the water level.

According to a number of scientists, sometimes there is a breakthrough of the surface by water masses, like lava during a volcanic eruption, and then these masses freeze. Icebergs that can be seen on the surface of the satellite testify in favor of this hypothesis.

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. The rarefied atmosphere of Europa contains mainly molecular oxygen. Apparently, this is due to 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 escapes 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 transferred to Olympus and made the 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, which were the result of active geological processes that took place 3.5 billion years ago, and 40% are an ancient powerful ice crust covered with many craters.

Possible internal structure of Ganymede

The core and silicate mantle of Ganymede generate heat, which 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 a large ocean is located closer to the surface.

But the thin layer of the atmosphere of Ganymede, consisting of oxygen, is similar to the atmosphere found on Europa. Compared to other satellites of Jupiter, flat craters on Ganymede practically do not form a hill and do not have a depression in the center, like craters on the Moon. Apparently, this is due to the slow, gradual movement of the soft ice surface.

Callisto

The satellite Callisto got its name in honor of another beloved of Zeus. With a diameter of 4820 km, it is the third largest satellite in the solar system, and this is approximately 99% of the diameter of Mercury, while the mass of the satellite is three times less than that of this planet.

The age of Callisto, like that of Jupiter itself and other Galilean satellites, is also about 4.5 billion years, but its distance to Jupiter is much greater than that of other satellites, almost 1.9 million kilometers. Due to this, the hard radiation field of the gas giant does not affect it.

The surface of Callisto is one of the most ancient surfaces in the solar system - it is about 4 billion years old. All of it is covered with craters, so that over time, each meteorite necessarily fell into an existing crater. There is no violent tectonic activity on Callisto, its surface does not warm up after formation, so it has retained its ancient appearance.

According to many scientists, Callisto is covered by a powerful ice layer, under which there is an ocean, and rocks and iron are contained in the center of the satellite. Its rarefied atmosphere is composed 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 comb-shaped concentric rings with a radius of up to 1900 kilometers. This whole picture resembles circles on the water from 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 in the solar system around the impact crater, although the crater itself is only 13th in size.

Valhalla - an impact basin 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 the construction of 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.

It will take 2 to 5 years to fly to Callisto. The first manned mission is planned to be sent no earlier than 2040, although the flight may begin later.

Model of the internal structure of Callisto

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

Jupiter's inner moons

Jupiter's inner moons are named so because of their orbits, which pass very close to the planet and are inside 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 weak ring system is replenished and maintained not only by inner satellites, but also by small inner moons, which are as yet invisible. Jupiter's main ring is supported by Metis and Adrastea, while Amalthea and Thebe have to maintain their own weak outer rings.

Of all the inner satellites, Amalthea, with its dark red surface, is of the greatest interest. The fact is that in the solar system there are no analogues to this. There is a hypothesis that such a color of the surface is due to 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 the capture of this satellite by Jupiter occurred from the outside, as it regularly happens with comets.

Jupiter's outer moons

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

Orbits of Jupiter's moons

Since some of the smaller moons have nearly identical orbits, it is assumed that they are the remnants of larger moons that have been destroyed by Jupiter's gravity. In pictures 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 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, as they consist of shiny ice, in Jupiter it is just a small dusty structure. This explains their late discovery, when a spacecraft first reached the Jupiter system in the 1970s.

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

Jupiter's ring system is made up of four main components:

Halo - a thick torus of particles, resembling appearance donut or disk with a hole;

Main ring, very thin and rather bright;

Two outer rings, wide but weak, called "spider rings".

The halo and main ring are composed primarily of dust from Metis, Adrastea, and probably a few other smaller moons. The halo is approximately 20,000 to 40,000 km wide, although its main mass is located no further than a few hundred kilometers from the plane of the ring. The shape of the halo, according to a popular hypothesis, is due to the influence of electromagnetic forces inside Jupiter's magnetosphere on dust particles of the ring.

Spider rings are very thin and transparent, like a web, they were named after the material of the satellites of Jupiter, Amalthea and Thebes that form them. The outer edges of the Main Ring are outlined by the satellites of Adrastea and Metis.

Jupiter's rings and inner moons

A satellite is a dense natural object that revolves around a planet. No specific scientific explanation provides a satisfactory answer to the question of how satellites came into existence, although there are several theories. 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 for 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 5262 km. The satellite is larger than Mercury and Pluto, and could easily be called a planet if it orbited the Sun. Ganymede has its own magnetic field. It was discovered by the Italian astronomer Galileo Galilei on January 7, 1610. The satellite orbits at a distance of about 1,0700,400 km from Jupiter and takes 7.1 Earth days to complete its orbit. The surface of Ganymede has two main types of scenery. It has lighter and younger regions, as well as a darker crater region. The atmosphere of the satellite is thin and contains oxygen in dispersed molecules. Ganymede is mostly made up of water ice and rock, and is believed to have subterranean oceans. The name of the satellite comes from the name of the prince in ancient Greek mythology.

Titanium

Titan is a moon 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 Christian 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% are methane, a small amount 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, except for the Earth, which has water bodies. The name of the satellite is taken from ancient Greek mythology, in honor of the ancient gods called titans. Ice and rock make up the bulk of Titan's mass.

Callisto

Callisto is the second largest moon of Jupiter and the third largest moon 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 got 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 has not been significantly affected by the planet's powerful magnetosphere. Water ice, as well as other materials such as magnesium and hydrated silicates, make up most of the moon's mass. Callisto has a dark surface and is thought to be a salty sea underneath.

And about

Io is the third largest moon of Jupiter and the fourth largest in the solar system. Its diameter is 3,643 km. The first satellite was discovered by Galileo Galilei in 1610. This is the most volcanically active space body along with the Earth. Its surface mainly consists of floodplains of liquid rocks and lava lakes. Io is located about 422,000 km from Jupiter, and makes a complete revolution around the planet in 1.77 Earth days. The satellite has a mottled appearance dominated by white, red, yellow, black, and orange. Io's atmosphere is dominated by sulfur dioxide. The satellite 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 major satellites

Other large satellites of the solar system include: the Moon (3,475 km), the Earth; Europe (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. The development of technology enables scientists to send spacecraft to different parts of the solar system in order to obtain more information about the planets and their satellites.

Table: TOP 10 largest satellites in the solar system