01/08/2026
Today in science history: In 1610, Galileo observed the 4 largest moons of Jupiter - Io, Europa, Ganymede, and Callisto! Learn more by clicking the link below or search "Galilean Moons".
The Galilean moons (/ˌɡælɪˈleɪ.ən/),[1] or Galilean satellites, are the four largest moons of Jupiter. They are, in descending-size order, Ganymede, Callisto, Io, and Europa. They are the most readily visible Solar System objects after Saturn, the dimmest of the classical planets; though thei...