What are the Galilean moons?

The Galilean moons refer to the four largest moons of Jupiter, which are Io, Europa, Ganymede, and Callisto. These celestial bodies were discovered by the astronomer Galileo Galilei in 1610, marking a significant milestone in both astronomy and our understanding of the solar system. Each of these moons is unique; for example, Io is known for its volcanic activity, Europa has a subsurface ocean that may harbor life, Ganymede is the largest moon in the solar system, and Callisto has a heavily cratered surface. Their discovery provided compelling evidence against the geocentric model of the universe, as it demonstrated that not all celestial bodies orbit the Earth. The significance of these moons lies not only in their size and diversity but also in the insights they give into planetary formation and geology.