Galilean Moons

Jupiter has 79 known moons and potentially far more that we don't know about. However, the main Jovian moons are known as the Galilean moons due to their discovery by Galileo Galilei in 1610. These moons(from top to bottom) are Io, Europa, Ganymede, and Callisto on the image above.

Properties:

Mass: 8.932*10²² kg

Radius: 1821.6 km

Mean Orbit Radius: 421700 km

Orbital Period: 1.77 days

Rotational Period: 1.77 days(synchronous)

Surface Gravity: 1.80 m/(s²)

Etymology: Io(Lover of Zeus, the Greek equivalent to Jupiter, the planet that Io orbits)

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Io is the innermost Galilean moon and is extremely volcanic. The reason for Io's volcanism is directly related to it having the innermost orbit around Jupiter. Its orbit causes Jupiter's tight pull on it along with the gravitational pull of the other Galilean moons to generate tidal heating and friction, giving rise to volcanoes. The volcanoes spew out sulfur and sulfur dioxide mainly and the plumes can reach about 500 km above the Io surface. Along with these volcanoes are also several mountainous regions, making Io the most geologically active body in the entire Solar System.

Properties:

Mass: 4.80*10²² kg

Radius: 1560.8 km

Mean Orbit Radius: 670900 km

Orbital Period: 3.55 days

Rotational Period: 3.55 days(synchronous)

Surface Gravity: 1.31 m/(s²)

Etymology: Europa(Lover of Zeus, the Greek equivalent to Jupiter, the planet that Europa orbits)

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Europa is the smallest Galilean moon and has the smoothest surface of any astronomical body in the Solar System. It is mainly composed of silicate and has a water-ice crust and most likely an iron-nickel core. The smoothness of the surface features on Europa has led scientists to believe that there is a subsurface water ocean that could house extraterrestrial life. There are also significant traces of sea salt on Europa's surface, which imply an interaction between the subsurface ocean and the rocky surface, which is an important criterion for evaluating habitability.

Properties:

Mass:1.48×10²³ kg

Radius: 2634.1 km

Semi-major axis: 1070400 km

Orbital Period: 7.15 days

Rotational Period: 7.15 days(synchronous)

Surface Gravity: 1.43 m/(s²)

Etymology: Ganymede(Lover of Zeus, the Greek equivalent to Jupiter, the planet that Ganymede orbits)

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Ganymede is both the largest and the most massive moon in the entire Solar System. It is the only moon known to have a magnetic field likely because of convection in the liquid core of the moon. However, the magnetic field is of course minuscule compared to Jupiter's so its effects are only slightly noticeable.

Properties:

Mass:1.08 * 10²³ kg

Radius: 2410.3 km

Semi-major axis: 1,882,700 km

Orbital Period: 16.69 days

Rotational Period: 16.69 days(synchronous)

Surface Gravity: 1.24 m/(s²)

Etymology: Callisto(Nymph who loved Zeus, the Greek equivalent to Jupiter, the planet that Callisto orbits)

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Callisto is the third-largest moon in the Solar System and is completely riddled with impact craters, making it the most heavily cratered body in the Solar System. The surface mainly consists of carbon dioxide, silicates, water-ice, and organic compounds.