It is called Ganymede and it is one of the four main satellites of Jupiter. With a diameter of more than 5,000 kilometers, this immense moon is larger than some planets in the Solar System such as Mercury, reaching a diameter of 4879 kilometers. That is, if Ganymede orbited the sun it would be a planet and not a satellite.
It is made up of three layers: a cast iron core, a rocky silica mantle, and a crust of ice in its outermost part. In some respects, Ganymede is quite similar to Earth. Faint traces of oxygen have been detected in its atmosphere , and it also has a magnetic field of its own , which is probably generated in a similar way to that of Earth. Its crust is divided into tectonic plates and solidified lava flows have been observed, although there does not appear to have been any recent activity. For all this, the largest moon in our solar system has inspired numerous science fiction writers such as the short story "Christmas on Ganymede" by Isaac Asimov.
