Which planet does not have a satellite? The largest satellites in the world
Satellites are small bodies that orbit planets. In the solar system, two planets (Mercury and Venus) have no satellites, the Earth has one, and Mars has two. A large number of satellites are attracted by the magnetic field of Neptune (13 satellites), Uranus (27 satellites), Saturn (60 satellites). But Jupiter has the largest number of satellites. There are 63 of them! Now you know which planet has more satellites in solar system.
In addition to such a huge number of satellites, Jupiter also has a system of rings. The first 4 satellites of Jupiter, the largest, were discovered by Galileo at the beginning of the 17th century. He gave them the names Europa, Ganymede, Io, Callisto (names of mythical heroes). With the development of telescopic technology, the remaining satellites began to be discovered; in the 70s of the last century, 13 of them were discovered. At the beginning of the third millennium, 47 more satellites of Jupiter were discovered. They are quite small, their radius reaches 4 km. Who knows how many more satellites of planets will be discovered over time, when the scientific and technological progress of mankind...
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Which planet has the most satellites?
The most a large number of Among the planets of the Solar System, the planet Jupiter has as many as 63 satellites. In addition to them, this planet also boasts a system of rings. The first 4 satellites were discovered back in the Middle Ages in the 17th century using a telescope, and the last (most of them) were discovered at the end of the 20th century using spacecraft. The size of most of them is not too large - only 2 to 4 kilometers in diameter. Saturn has slightly fewer satellites - 60. But one of its satellites, Titan, is the second largest in the solar system and has a diameter of 5100 km.
The third largest number of satellites is Uranus. He has 27 of them. And planets such as Venus and Mercury have no satellites at all. 5-11-2010
Have you read the answer to the question Which planet has the most satellites? and if you liked the material, bookmark it - “Which planet has the most satellites?? . Which car is best for taxi work? This is controversial...
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At Jupiter...
Mercury has no satellites.
Venus also has no satellites
The Earth has one satellite: the Moon
The Moon is the only natural satellite of the Earth. It is the second brightest object in the earth's sky after the Sun and the fifth largest natural satellite in the solar system. It is also the first (and as of 2009, the only) extraterrestrial object of natural origin visited by humans. The average distance between the centers of the Earth and the Moon is 384,467 km.
The planet Mars has two satellites: Phobos (Greek - fear) and Deimos (Greek - horror).
Both satellites rotate around their axes with the same period as around Mars, therefore they are always turned to the planet with the same side. The tidal influence of Mars gradually slows down the movement of Phobos, and will eventually lead to the fall of the satellite onto Mars. On the contrary, Deimos is moving away from Mars.
Jupiter has 63 moons
The moons of Jupiter are the natural satellites of the planet Jupiter. To date, scientists know 63...
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The central star of our system, around which all the planets pass in different orbits, is called the Sun. Its age is about 5 billion years. It is a yellow dwarf, so the size of the star is small. Its thermonuclear reactions are not consumed very quickly. The solar system has reached approximately the halfway point of its life cycle. After 5 billion years, the balance of gravitational forces will be disrupted, the star will increase in size and gradually warm up. Nuclear fusion converts all of the sun's hydrogen into helium. At this point, the size of the star will be three times larger. Ultimately, the star will cool down and shrink. Today the Sun consists almost entirely of hydrogen (90%) and some helium (10%).
Today, the satellites of the Sun are 8 planets, around which other celestial bodies revolve, several dozen comets, as well as a huge number of asteroids. All these objects move in their orbit. If you add up the mass of all the solar satellites, it turns out that they are 1000 times lighter than their star....
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Just the other day my mother told me: she comes into the room in the evening, sees me (I was only five or six years old) looking outside the window and crying. When asked what upset me, I answered: “I feel sorry for the Moon, the Earth only has one.” The next day, mom opened the book to a page about the planet, which there were satellites more than everyone else- so as not to reassure my daughter later.
Planet with the most moons
If we talk about the solar system, the undisputed leader here is Jupiter. Him as many as 69 satellites- those who are definitely not lonely without company. Moreover, these are only those that we managed to find - it is assumed that in practice theirabout a hundred.
It was thanks to them that Jupiter acquired its unusual striped color.
Galilean satellites
The very first moons of Jupiter were discovered by Galileo. Of course, his telescope was not very powerful, which is why he saw only four the biggest Jovian moons:
I came up with names for them Simon Mari. His first records were actually dated earlier than Galileo, but the scientist made a fatal mistake - he delayed the publication. Marius tried for a very long time to prove that he was the first to discover satellites. He failed, but as a consolation prize he received opportunity to name them as he pleases.
And I chose names from mythology for the name - in honor of the beloved of the god Jupiter. The idea was not bad, but even the loving god clearly did not have so many loving affections.
Jupiter - the thief of satellites
Some of Jupiter's moons rotate in the opposite direction. It is believed that they were ordinary cosmic bodies, they moved on their own and did not touch anyone, but unfortunately they ended up in a gravitational field gas giant– and now they have to revolve around him.
But since you’re going to revolve around the invader, you have to do it in defiance of everyone. This movement is called retrograde. They are quite easy to recognize by their names. The rule is: if the name ends with the letter “e”, then the satellite is moving in the opposite direction.
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Since childhood, I loved astronomy, which is why I studied this science well. My favorite planet was Jupiter. Jupiter -largest planet Solar system, this gas giant is the fifth in distance from the Sun, and has a large number of satellites.
Jupiter has the largest number of satellites
Since ancient times, Jupiter was known to our ancestors; they composed many legends about this planet and called it by the names of their deities. The modern name of the planet is named after the Roman deity - thunderer Jupiter. On Earth, Jupiter can be seen with the naked eye. and it's not strange, because The planet is second only to the Sun in mass. Some scientists believe that if Jupiter were a little larger, it would turn into another Sun in our system. Since the planet does not have a solid surface or liquid water, it is believed that life on it is impossible, but scientists suggest the existence of life in upper layers its atmosphere.
Large moons of Jupiter
Jupiter Andhas at least sixty-seven satellites, but perhaps there are many more of them, the number of satellites may exceed a hundred. It is ironic that the satellites were given the names of deities somehow related to the divine Jupiter. The most famous moons of Jupiter:
- Europa is a satellite of Jupiter, whichhas an ocean and where there is the presence of water, the presence of life is not excluded. Also in the ocean waters of Europe there is a huge amount of oxygen, and this, in turn, makes it possible for the emergence of not only single-celled, but also more complex forms of life;
- And about - volcanic planet, which is covered with great volcanoes and the products of their eruptions;
- Ganymede -largest satellite in the entire solar system. Covered with deep craters, which indicate frequent meteor showers;
- Callisto- a planet that also has ocean water, like Europa, life is possible on Callisto.
These four satellites synchronously rotate around Jupiter and always face one side towards it.
Small satellites of Jupiter
The remaining satellites are often irregularly shaped and represent rocky bodies. One of the most interesting small satellites - Amalthea. Amalthea was once a whole body, but due to meteorite bombardment, it broke up into parts, which were united under the influence of gravity, but never became a single whole.
It is assumed that the giant Jupiter once had many more satellites, but due to the planet's strong gravity, they fell to its surface.
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During my school years I really loved astronomy. Observations of stars, observation diaries - there was a special romance in this, which not everyone understands. The telescope was a cherished dream for me. And when they gave it to me, first I began to look at the planets. And my first object was not Saturn, with its rings. It was Jupiter, because of the galaxy of satellites.
How many moons does Jupiter have?
At the moment, 79 satellites are known: from dwarfs with a diameter of several kilometers to almost full-fledged planets. In addition, Jupiter has its own ring system. In addition, the number 79 is most likely not final. New satellites are still being discovered today, the last one became known this year, 2018.
It is simply impossible to list all these objects; most of them have alphanumeric names. But it’s worth mentioning the most basic ones, discovered by Galileo Galilei in 1610. These include:
- Europe;
- Ganymede;
- Calisto.
Their names were given by Simon Marius, another great scientist. They are taken from ancient Greek myths. These satellites can be considered the most unusual. Thus, Europe is completely covered with ice, under which there is an ocean. Scientists even admit the presence of life in it. And Io is the owner of the largest active volcano in the solar system.
Why does Jupiter have so many moons?
The number of Jupiter's satellites can be attributed to the fact that it is the largest object in our native solar system, after the Sun itself. Therefore, in the past, it easily captured small planets flying in similar orbits into its gravitational field. It also captured various dust, fragments, and asteroids, which served as the foundation for the formation of some satellites already in orbit around the giant.
How many satellites do other planets have?
Don't forget that other planets also have beads of objects orbiting around them. So, Saturn has 62 of them, Uranus has 27, Neptune has 14. Not far away is the dwarf Pluto, which has as many as five satellites.
So it turns out that our solar system is amazing and unique. Sometimes, to see miracles, all you have to do is look at the sky.
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In the summer of 2011, I excitedly watched the launch of the Juno interplanetary station to study Jupiter. It had to fly to the planet that had the most satellites in the solar system. The robot station did it. On solar powered she transmitted so much data that scientists will be busy deciphering them for several years.
How many moons does Jupiter have?
It is almost 2.5 times larger than all the planets in the solar system together. This huge mass, compared to the Sun, even shifts the center of gravity beyond its limits. Such colossal size and weight of the planet determine the huge number of satellites and the presence of dust rings.
In the 17th century, Galileo saw large satellites through a telescope:
- Europe;
- Ganymede;
- Callisto.
By the seventies of the 19th century, 9 more satellites were discovered.
Voyager 1, traveling to Saturn past Jupiter, recorded the presence of three new satellites in 1979. Later, 51 satellites were discovered thanks to new types of telescopes.
Jupiter is believed to have at least 100 “moons,” the study of which continues.
The largest
Io, the closest satellite to Jupiter, is affected by the gravitational forces of both the planet and Ganymede with Europa, which leads to heating of the body, deformation and active volcanic activity. Io's movement causes severe thunderstorms on Jupiter.
Europa is covered in water, in which life is believed to exist. The temperature on the surface is 150-220 degrees Celsius below zero - a “crystal” satellite with a metal core and a rocky mantle. There is oxygen in the atmosphere.
Ganymede is the largest moon in the Solar System. It is larger than Mercury. The surface is covered with ice and dotted with numerous craters, and oxygen is found in the atmosphere.
Callisto consists of water and stones and is the body with the most old surface. This is the site of a planned space base for Europa exploration.
Internal and external
In inner orbit to Io are:
- Metis;
- Amalthea;
- Adrastea;
- Thebe.
59 external satellites have been recorded. Those close to Jupiter rotate with it in the same direction, the rest - in the opposite direction.
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To the question: Which planet in the solar system has the most satellites? given by the author Lissa the best answer is Maybe I’m wrong, but at the moment the planet Earth has the most satellites. Only these satellites are artificial (and the question didn’t say which ones). There are several hundred of them.
Answer from Igor Ermolin[newbie]
The correct answer is SATURN
Answer from Wake up[newbie]
and exactly?
Answer from Eurovision[newbie]
Jupiter has Mercury-0 Venus–0 Earth-1 Mars-2 Jupiter-63 Saturn-60 Uranus-27 Neptune-13 The planet Jupiter has 63 satellites. Whereas the planet earth has only one satellite - the Moon. There are 63 satellites of Jupiter greatest number satellites discovered to date from all the planets of the solar system. In addition to the largest number of satellites, Jupiter also has a system of rings.
Answer from Olya[guru]
At Jupiter.
Answer from User deleted[active]
Saturn
Answer from Marina[expert]
Jupiter
Answer from User deleted[expert]
There is a table here Planet Distance from the Sun Orbital period Rotation period Diameter, km Mass, kg Number of satellites Density g/cm
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Satellites of the planets
Mercury and Venus have no satellites. The remaining planets, with the exception of the Earth, have satellites immeasurably smaller than their planets. The Earth has only one natural satellite - the Moon, but it is unusually large compared to itself. Moon smaller than Earth in diameter only 4 times. The largest planet, Jupiter, has the most satellites - 12. The next most massive planet, Saturn, has 10 of them, and the last one was discovered only in 1966. Uranus has 5 satellites, Neptune and Mars have 2 each. The largest of the satellites are Titan (a satellite of Saturn) and Ganymede (the third satellite of Jupiter). They are 1.5 times the diameter of the Moon and slightly larger than Mercury. Titan is the only moon to have an atmosphere (made of methane).
All satellites for which rotation has been established, including the Moon, are always turned to their planet with the same side. Therefore, their stellar rotation periods are equal to their periods of revolution around their planets. As a result, it is impossible to see from any planet reverse side her companions. In relation to the Sun, the period of rotation of satellites around the axis is longer than in relation to the stars, since during the revolution of the satellite the planet along with it will travel some more arc along its circumsolar orbit.
A sidereal month is the period of the Moon's revolution around the Earth relative to the stars; A synodic month is the period of revolution of the Moon around the Earth relative to the Sun. A synodic month is the period of time between equal phases of the Moon. The sidereal month is 27.3 days, and the synodic month is 29.5 days.
The point of the elliptical lunar orbit closest to Earth is called perigee, and the most distant point is called apogee.
The moon is visible to us as a narrow crescent, the rest of its disk also glows slightly. This phenomenon is called ashen light and is explained by the fact that the Earth illuminates the night side of the Moon with reflected sunlight.
It is easy to understand that the phases of the Earth and the Moon are mutually opposite. When the Moon is almost full, the Earth is visible from the Moon as a narrow crescent.
Returning to the satellites of the planets, we note that four largest satellite Jupiter can sometimes be seen even with prism binoculars. Through a telescope, in a few hours you can see how the satellites move noticeably, sometimes passing between Jupiter and Earth, and sometimes going behind Jupiter’s body or into its shadow, into an eclipse. Observing these eclipses of satellites, Roemer in the 17th century. discovered that the speed of propagation of light is finite, and established its value.
Many of the planets' satellites are interesting because of their motion. The moons of Mars are very small. The largest of them is Phobos. It has a diameter of 16 km and is located from the surface of Mars at a distance less than the diameter of the planet. Phobos orbits Mars three times faster than the planet itself rotates on its axis. Therefore, it rises twice a day in the west and twice completely changes all phases, sweeping across the sky.
The distant moons of Jupiter and Saturn are very small, and some of them point in the direction opposite to the rotation of the planet itself.
All 5 satellites of Uranus rotate in the opposite direction, and the planes of their orbits, like the planet’s equator, are almost perpendicular to the plane of Uranus’s orbit.
Satellites and planets of the solar system
The natural satellites of planets play a huge role in the life of these space objects. Moreover, even we humans are capable of feeling the influence of our planet’s only natural satellite – the Moon.
The natural satellites of the planets of the solar system have aroused keen interest among astronomers since ancient times. To this day, scientists are studying them. What are these space objects?
Natural satellites of planets are cosmic bodies of natural origin that orbit around planets. The most interesting for us are the natural satellites of the planets of the solar system, since they are in close proximity to us.
There are only two planets in the solar system that do not have natural satellites. These are Venus and Mercury. Although it is assumed that Mercury previously had natural satellites, this planet lost them in the process of its evolution. As for the rest of the planets in the solar system, each of them has at least one natural satellite. The most famous of them is the Moon, which is our planet’s faithful cosmic companion. Mars has, Jupiter -, Saturn -, Uranus -, Neptune -. Among these satellites we can find both very unremarkable objects, consisting mainly of stone, and very interesting specimens, which deserve special attention, and which we will discuss below.
Classification of satellites
Scientists divide planetary satellites into two types: satellites of artificial origin and natural ones. Satellites of artificial origin or, as they are also called, artificial satellites are spacecraft created by people that make it possible to observe the planet around which they orbit, as well as other astronomical objects from space. Typically, artificial satellites are used to monitor the weather, radio broadcasts, changes in the topography of the planet's surface, and also for military purposes.
The ISS is the largest artificial satellite of the Earth
It should be noted that not only the Earth has satellites of artificial origin, as many people believe. More than a dozen artificial satellites created by mankind revolve around the two closest planets to us - Venus and Mars. They allow you to observe climatic conditions, changes in terrain, as well as receive other relevant information regarding our space neighbors.
Ganymede is the largest moon in the solar system
The second category of satellites - natural satellites of planets - is of great interest to us in this article. Natural satellites differ from artificial ones in that they were created not by man, but by nature itself. It is believed that most of the satellites of the solar system are asteroids that were captured by the gravitational forces of the planets of this system. Subsequently, the asteroids took on a spherical shape and, as a result, began to revolve around the planet that captured them as a constant companion. There is also a theory that says that the natural satellites of planets are fragments of these planets themselves, which for one reason or another broke away from the planet itself during the process of its formation. By the way, according to this theory, this is how the Earth’s natural satellite, the Moon, came into being. This theory is confirmed chemical analysis composition of the Moon. He showed that the chemical composition of the satellite is practically no different from chemical composition our planet, where the same chemical compounds are present as on the Moon.
Interesting facts about the most interesting satellites
One of the most interesting natural satellites of the planets of the solar system is the natural satellite. Charon, in comparison with Pluto, is so huge that many astronomers call these two space objects nothing more than a double dwarf planet. The planet Pluto is only twice the size of its natural satellite.
The natural satellite is of keen interest to astronomers. Most of the natural satellites of the solar system's planets are composed primarily of ice, rock, or both, resulting in them lacking an atmosphere. However, Titan has this, and it is quite dense, as well as lakes of liquid hydrocarbons.
Another natural satellite that gives scientists hope for discovering extraterrestrial life forms is Jupiter’s satellite. It is believed that under the thick layer of ice that covers the satellite there is an ocean, inside of which there are thermal springs - exactly the same as on Earth. Since some deep-sea life forms on Earth exist thanks to these sources, it is believed that similar life forms may exist on Titan.
The planet Jupiter has another interesting natural satellite -. Io is the only satellite of a planet in the solar system on which astrophysicists first discovered active volcanoes. It is for this reason that it is of particular interest to space researchers.
Natural satellite research
Research on the natural satellites of the planets of the Solar System has interested the minds of astronomers since ancient times. Since the invention of the first telescope, people have been actively studying these celestial objects. The breakthrough in the development of civilization made it possible not only to discover a colossal number of satellites of various planets of the solar system, but also to set man on the main, closest to us, satellite of the Earth - the Moon. July 21, 1969, American astronaut Neil Armstrong and his crew spaceship Apollo 11 first set foot on the surface of the Moon, which caused rejoicing in the hearts of humanity at that time and is still considered one of the most important and significant events in space exploration.
In addition to the Moon, scientists are actively studying other natural satellites of the planets of the solar system. To do this, astronomers use not only visual and radar observation methods, but also use modern spacecraft, as well as artificial satellites. For example, the “” spacecraft for the first time transmitted to Earth images of several of Jupiter’s largest satellites:,. In particular, it was thanks to these images that scientists were able to record the presence of volcanoes on the moon Io, and the ocean on Europa.
Today, the global community of space researchers continues to be actively engaged in the study of the natural satellites of the planets of the solar system. In addition to various government programs, there are also private projects aimed at studying these space objects. In particular, the world famous American company Google is currently developing a tourist lunar rover, on which many people could take a walk on the Moon.
The science
Our Solar System contains a huge number of different cosmic bodies, including 200 large satellites orbiting the main planets, dwarf planets and even asteroids. Many of these satellites have interesting features. In this article you can get acquainted with the 10 most interesting satellites of our star system and learn about their features.
1) Nereid, satellite of Neptune
Nereid was discovered in 1949 Gerard Kuiper. It is Neptune's third largest moon. It has the most eccentric orbit of all the satellites in the solar system. Because of this, the distance between the planet and its satellite varies greatly. The closest the satellite can get to Neptune is 1.4 million kilometers. The farthest it can go is 9.6 million kilometers. To make one revolution around Neptune, given such a far distance from it, Nereid requires 360 Earth days.
2) Mimas, satellite of Saturn
This small satellite was discovered in 1789 William Herschel. The average diameter of this object is about 400 kilometers. Mimas is notable for the fact that on its surface there is a giant crater Herschel with a diameter of about 130 kilometers and a depth of 10 kilometers. Herschel is not the largest crater of the solar system's satellites, but it is very unusual. The crater covers one third of Mimas's surface and makes it look like the Death Star station from Star Wars.
3) Iapetus, satellite of Saturn
Discovered in 1671 Giovanni Cassini, Saturn's moon Iapetus has been recognized as one of the strangest moons in the solar system. The diameter of Iapetus averages 1,460 kilometers. Distinctive feature of this satellite is that it has sections different color that reflect light differently. One half of the planet is pitch black, while the other half is exceptionally light and bright. Because of this, we can only observe the satellite when it appears on one side of the planet. Iapetus also has a mountain range - an equatorial mountain ring, which reaches a height of about 10 kilometers and encircles the object along its equator. Scientists have put forward 2 hypotheses to explain the appearance of these mountains. According to one version, the ring formed at the beginning of the satellite’s existence, when Iapetus rotated much faster than it does now. Other scientists believe that the mountain range was formed from material from another satellite, which belonged to Iapetus itself, but crashed, and its debris settled on Iapetus' equator.
4) Dactyl, satellite of the asteroid Ida
Discovered in 1995 by spacecraft Galileo, the satellite of the asteroid Ida - Dactyl - has about a kilometer in diameter. This satellite is notable because it was the first satellite discovered to orbit an asteroid. Scientists cannot yet say for sure about the origin of this satellite and do not know whether it is part of its native asteroid, or was once captured by this asteroid. Dactyl proves the existence of satellites on asteroids. After that, scientists noticed another two dozen similar satellites around various other asteroids in the Solar System.
5) Europa, satellite of Jupiter
Europa has been discovered Galileo Galilei in January 1610. It is quite a bit smaller than our Moon. Europa's surface is striking, carved with dark intersecting lines. Scientists suggest that the lines represent cracks and breaks in Europa's ice shell. Perhaps the cracks formed due to the influence of Jupiter and other satellites orbiting the planet. Beneath Europa's thick layer of ice there may be an ocean of liquid salt water that makes the moon special. Unlike Earth, it is believed that Europa has a very deep ocean, so it completely covers the entire satellite. Since Europa is located quite far from the Sun, its ocean froze, forming a crust about 100 kilometers thick. Perhaps due to internal more high temperature The water under the ice crust may remain liquid.
6) Enceladus, satellite of Saturn
Enceladus is the sixth largest moon of Saturn. It is not the largest, but has a number of interesting features. Enceladus was discovered in 1789 William Herschel. It is the brightest cosmic body in the solar system and reflects 100 percent sunlight from its surface. This fact makes it one of the coldest places, the temperature on the surface of the satellite is about minus 200 degrees Celsius. As you can see in the image, this satellite has a number of impact craters, but there are also quite smooth areas that indicate that in the geologically recent past the surface of the satellite was leveled. On south pole The satellite has large dark faults, which also indicate recent geological activity. These fractures release tons of material that makes up Saturn's E ring.
7) Io, satellite of Jupiter
Io was discovered in January 1610 by the same Galileo Galilei. It is slightly larger than our Moon. Io is the most volcanically active place in the solar system. The satellite is covered with many volcanoes, which release jets of substances at a distance of about 300 kilometers above the surface. Typically, an object of this size should have ceased volcanic activity a very long time ago, but due to Io’s orbital resonances with Jupiter, Europa and Ganymede, tidal heating occurs in the bowels of the satellite. If we omit the details, we can say that the increased volcanic activity of the satellite is associated with nearby cosmic bodies and its composition internal characteristics. Tidal heating causes most of the material lying beneath the surface to remain in a liquid state, which constantly changes the surface of the satellite.
8) Titan, satellite of Saturn
Titan is the only satellite besides our Moon on whose surface a spacecraft has landed. It was opened in 1655 Christian Huygens. Titan is the second largest moon in the Solar System. It is covered in a dense, foggy atmosphere consisting mainly of methane, nitrogen and ethane. This satellite is known for having an atmosphere similar to that of a planet. Also this the only place in the solar system, where, as scientists have proven, there is liquid on the surface, although this liquid is far from water, but methane.
9) Triton, satellite of Neptune
Triton was discovered in October 1846 by astronomer William Lassell, 17 days after the discovery of Neptune itself. This is the largest of the satellites of the planet Neptune. Triton has the distinction of being the only large moon in the solar system that orbits a planet in the opposite direction to the planet's rotation. This suggests that Triton is a captured satellite of Neptune, because all natural satellites in the solar system rotate in the same direction as their planets. The only thing is that scientists cannot yet come to a consensus on how Neptune captured such a large body into its orbit. Triton is one of the coldest places in the solar system. When Voyager 2 flew past it in 1989, he found that Triton's temperature remained minus 235 degrees Celsius, that is, it was close to absolute zero. Voyager 2 also helped discover active geysers on Triton, so Triton is considered one of the few geologically active moons in the Solar System.
10) Ganymede, satellite of Jupiter
Discovered in 1610 Galileo Galilei, Ganymede is the largest moon in the solar system. It is larger than the planet Mercury and is also about three times the size of Mars. It is so large that it would be considered a planet if it orbited the Sun rather than Jupiter. A notable feature of this satellite is that it is the only satellite in our system that has its own magnetic field. It has a molten iron core, which creates a magnetic field. In 1996, the space telescope Hubble discovered a thin layer of oxygen around the satellite, but it is so thin that it cannot support life.