Above our moon, are seen the planet Jupiter with its largest 4 (out of 67? ) moons. The moons as discovered by Galileo were known as Callisto, IO, Europa, Ganymede. IO is volcanic with fatal levels of nuclear hazard on its environment while Europa is Icy. Today, the phenomenon of aura produced on Jupiter’s moon Europa, was explained briefly. Click on preceding link.
Galileo had observed the 4 largest moons, as named above, with his small telescope which is today known as Galileo, which was only the 2nd ever made telescope in the history of humanity, with about 30 times more resolving power than the first ever made by an engineer from Netherlands.
( — need to check on that specification of “30 x resolving power” in units of telescope resolving power of 1st )