Which moons are known as the Galilean moons?

The Galilean moons are specifically Io, Europa, Ganymede, and Callisto, which were discovered by Galileo Galilei in 1610. These four largest moons of Jupiter are notable for their significant sizes and the unique geological features they exhibit.

Io is known for its intense volcanic activity, being the most geologically active body in the solar system. Europa has a smooth ice-covered surface, suggesting a subsurface ocean, which makes it a candidate for potential extraterrestrial life. Ganymede is the largest moon in the solar system, larger than the planet Mercury, and has a mix of water ice and rocky material. Callisto, the outermost of the four, is heavily cratered and is thought to have a subsurface ocean as well.

This grouping of moons is important in the study of planetary science because they offer insight into the diversity of celestial bodies and dynamic processes occurring in our solar system. The other choices contain moons from different planets that do not share the same historical significance or classification as the Galilean moons.