Simulations suggest there may have been several generations of Galilean satellites in Jupiter's early history.
So, the determination of its orbital period, along with those of the other Galilean satellites, was an early focus for astronomers.
However, the names of the Galilean satellites fell into disfavor for a considerable time, and were not revived in common use until the mid-20th century.
This is different from other Galilean satellites, where the reverse is true.
Observers on the sides of the Galilean satellites facing away from the planet would never see Jupiter, for instance.
Until the discovery of the Galilean satellites in 1610, however, there was no opportunity for referring to such objects as a class.
It is the seventh moon and third Galilean satellite outward from Jupiter.
Io is the closest of the Galilean satellites to Jupiter.
Despite its size, it has not been featured in fiction as much as the other Galilean satellites.
Ganymede, the third Galilean satellite, has a subarctic climate, large bodies of water, and a six month rotation period.