DECRYPTION – It is the tidal forces exerted by Jupiter which are at the origin.
Io, Europa, Ganymede and Callisto: the four main moons of Jupiter are also called “Galilean satellites”, in homage to Galileo. It was in fact the Italian astronomer who made their discovery, in 1610, by pointing a spyglass of his own design at Jupiter, which will go down in legend as the first telescope to have been pointed skyward, marking the beginning of the era of instrumental astronomy.
If the observation was obviously interesting in itself, it also constituted, at the time, a small revolution: it meant that there existed another world than the Earth around which gravitated elements of the cosmos. In the wake of Copernicus, who placed the Sun at the center of the Universe, this was a new nail in the coffin of geocentrism.
Heavenly pizza
It will nevertheless be necessary to wait nearly four centuries, and the overflights of NASA’s Voyager probes in the 1980s, to finally have a first detailed glimpse of the surface of these remote worlds. First surprise…
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