Moons of our Solar System: Ganymede

Hi,Největší měsíc Sluneční soustavy Ganymede
here it comes here it goes, the post about Ganymede.
Ganymede was in Greece mythology really beautiful guy. Zeus decided that he wants him on the Olymp so he made him waiter. Thats about it, Ganymede is only Jupiter`s moon that is named after male.

With other Galilean moons Ganymede was discovered by Galileo in the year 1610.

Now for some facts, Ganymede is the largest moon of our Solar System. It is so large that if he would orbit Sun instead of Jupiter he would be considered planet. Ganymede has greater volume than Mercury, but is not so heavy (has about half of Mercury`s mass).
Still even with such a low density (1,936g\cm3), he is twice as heavy as Moon.

Ganymede is orbiting Jupiter with really small excentricity even that there are other moons which could be distracting his orbit. Orbit distance is about 1 million kilometers and he is able to go around every seven days. As other moons he is tidaly locked to Jupiter.

When it comes to interior of Ganymede it is very interesting. As you can see on the surface is ice crust (and quartz rock). When you check the first picture you can see that there are mainly two shades, lighter and darker. Lighter seems to be newer and without impact craters. Same as on for example Moon or Mars, some tectonic activity probably smoothed everything out.

Right under ice crust there is REAL liquid water! It was found by Hubble Space Telescope when astronomers found out that aurora of Ganymede should be “changing|waving” by about 6° (caused by Jupiter magnetosphere) while it does only by 2° which is by salty ocean which has huge impact because it is electricly conductive. This ocean`s volume is larger than of Earth`s volume, it is 100 kilometers deep.

Ganymede is the only known moon to have its own magnetosphere. It is created by convection of liquid interior of Ganymede (it was first discovere by the satellite Galileo). Convection is process which for example occurs in ocean when cold water goes up where it heats and then sinks again, then its temperature drops and whole process repeats.

Ganymede was created in the accretion disk of Jupiter when whole Solar System began to form. Because he was formed closer to Jupiter than Callisto, liquid and solid parts more easily separated. It took 10,000 years to form him. Example of accretion disk is on the right.

Ganymede, Europa and Io are in orbital resonance. This means that are in some (1:2:4) ratio of orbits. For one Ganymede`s rotation there are two rotations of Europa and four of Io. I found gif of this on wikipedia and I could watch it whole day (not to scale). This resonance also causes heating of their interior because of friction.

First mission to which saw Ganymede from close look was Pioneer 10 and 11. Then Voyager had much better look and finally Galileo (and then New Horizons). For the year of 2020 is planned another mission which would orbit Jupiter.

Dragallur

Sources
https://www.quora.com/Which-moon-is-bigger-than-a-planet
plus wikipedia pages like Ganymede, Orbital resonance..

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