The discovery last summer of twelve new natural satellites orbiting this planet brings Jupiter’s moons to 79, making it the most well-matched planet in the solar system .
Since Galileo Galilei discovered the four large satellites of Jupiter , interest in the bodies that orbit around this planet has not stopped growing.

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1. Jupiter’s moons: characteristics of the planet.
2. The 4 moons of Jupiter discovered by Galileo.

3. The 12 newly discovered moons of Jupiter.
4. Conclusion How many Mondays does Jupiter have Jupiter

‘s moons: characteristics of the planet
On January 7, 1610, the revolutionary astronomer Galileo Galilei discovered with his rudimentary telescope that three strange bodies revolved around Jupiter. Then he realized that there were not three, but four , and that they could not be stars, since they were moving around him. This is how Jupiter’s four moons were revealed.
Jupiter is the fifth planet in the solar system, and is part of the group of outer or gaseous planets. After the sun, it is the star with the most volume and mass, twice more than the rest of the planets, and it is also the oldest in the solar system , even preceding the sun. Jupiter is made up of helium and hydrogen, and is one of the brightest planets.
After a week of observations, Galileo Galilei was convinced that they were natural satellites, since the celestial bodies never left the vicinity of Jupiter and moved with it. At that time, it was already established that the stars did not revolve around the Earth, and that allowed the nature of these new bodies to be more accurately identified.

The 4 moons of Jupiter discovered by Galileo
Initially, the astronomer baptized the satellites of Jupiter with the names I, II, III and IV, categories that were maintained for two centuries until in the middle of the 19th century they were given the new names with the names that are known today.

1. Io, the volcanic moon of Jupiter
It is a custom to use Greco-Roman mythology to baptize the celestial bodies, and the first of the Galilean satellites received the name of Io, one of the maidens who fell in love with King Zeus (Jupiter , in Roman mythology). Initially, Galileo called it Jupiter I, because it was the closest natural satellite to that planet .
Indeed, Io is the closest Galilean satellite to Jupiter, although in size it occupies the third position: it has a diameter of 3,600 km. Although it has a great density, it is the star with the least water in the entire solar system , and in addition, it is formed by large plains and more than 400 active volcanoes, being one of the most geologically active bodies.
According to the studies of the Voyager 1 probe in 1979, the activity of the volcanoes has cleaned the craters from the surface. Unlike our volcanoes, those on Io expel sulfur dioxide more than 300 km high , but low gravity helps this material to be permanently expelled from the surface and ionized by Jupiter’s magnetic field.
In addition to its fascinating features, it is important because for centuries after its discovery it served to validate Kepler’s third law of planetary gravitation and Copernicus’s heliocentric model, among other things.

2. Europa

Europa is the smallest of Jupiter’s four satellites, but the sixth largest satellite in the solar system: 1,561 km in diameter. Galileo called it Jupiter II, but in the 19th century it was baptized with that name in honor of the goddess Europa, lover of Zeus and mother of King Minos of Crete.
Known in astronomy as Jupiter’s icy moon, astronomers believe that if there is extraterrestrial lifein the universe will be in this natural satellite. In 2017, scientists concluded that, due to its characteristics, it is likely to contain life, and announced the intention to send missions in the near future.
The appearance of Jupiter’s icy moon is striking, for the surface is a pattern of spots like a child’s scribbles. These are cracks in the sky beneath which lie, expanding and shrinking due to the tidal forces generated by gravity, ice shelves floating on an ocean of liquid water .
That is why scientists believe that this moon of Jupiter has twice as much water as all the oceans on Earth, a basic premise for the creation of life.

3. Ganymede
Ganymede is the largest satellite of Jupiter and the solar system (5,268 km), and the only one with a magnetic field . It gets its name from the beautiful mythological hero kidnapped by Zeus to make him his lover and cupbearer to the gods. Galileo baptized it as Jupiter III, for being the third closest satellite of Jupiter to the planet.
Ganymede’s appearance offers two predominant terrain types: one bright and ridged, and one with dark grooves, referring to its composition of equal parts silicon and water ice. In its core lies molten iron which is the cause, according to hypotheses, of Ganymede’s magnetic field, much less than the powerful magnetism of Jupiter.
The dark areas are riddled with craters and are four billion years old, while the white areas are more recent and are caused by tidal heating and tectonic movements .
In addition, the Hubble Space Telescope has detected the presence of oxygen in Ganymede’s atmosphere, caused by radiation from the surface ice. Ganymede has been taken as a reference, due to its large size, for many works of science fiction .

4. Callisto

The second largest of Jupiter’s moonsand the third largest natural satellite in the solar system is Callisto, a star made up of rock and ice that Galileo discovered later than the first three and which he called Jupiter IV. The farthest of the four Galilean satellites was renamed Callisto, the nymph goddess, lover of Zeus and mother of Arcadius.
Callisto is 2,410 km in diameter and is excluded from the orbital resonances of the first three moons. This means that it is not influenced by gravity causing tidal forces, nor by Jupiter’s magnetosphere .
It is believed that it was formed by the aggregation of the whirlpool of matter that surrounded Jupiter, but its slowness and the absence of tidal forces determined its chemical differentiation. It is believed that it may host an inner ocean compatible with life, although with less prospects than Europe. However, its characteristics make it more suitable for exploration .
And it is that in 2003 NASA considered the future human exploration of the outer solar system and, after carefully studying the context, chose Callisto as the best place to stabilize the scientific base of the mission. Low radiation and geological stability make it the most suitable place for future exploration.

12 newly discovered moons of Jupiter
Two centuries after the discovery of Jupiter’s four satellites, dozens more moons were discovered orbiting the giant planet. However, unlike Jupiter’s four moons, these natural satellites were much smaller and made up, together with the rings, only 0.0003% of the total mass orbiting them .
Metis, Amalthea, Thebe, Themistus, Lysithea, Dia, Carpus, Jocasta, Hermipe, Arce, Caldona and Eurydome are just some of the names given to these dwarf satellites , in honor of the lovers, daughters and conquests of the god Jupiter. In total, the number of moons increased to 67, until a recent discovery raised it to 79.

Conclusion: How many moons does Jupiter have?
Last summer, scientists were searching for objects outside the solar system when a tiny cluster of stars caught their eye around Jupiter. After analyzing it, 12 more celestial bodies were discovered orbiting the planet, although its size is even smaller than that of the moons discovered so far.
This suggests that there are many more moons orbiting the planet, which is by far the planet in the solar system with the most natural satellites. It is believed that these stars were born shortly after Jupiter, and that the magnetism of this giant planet acted like a magnet, attracting matter around it .
Among these new ones, an especially strange one was found that has been nicknamed “the rare one”. Then baptized as Valetudo, the great-granddaughter of the god Jupiter, this star has a strange way of orbiting, because located in the farthest ring of the planet, it orbits in the opposite direction to the other moons .

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