the Galilean moons

The Galilean moons are four large moons orbiting Jupiter, discovered by Galileo Galilei in 1610. They are Io, Europa, Ganymede, and Callisto. Io is volcanically active with colorful, sulfur-rich surfaces. Europa has a smooth icy shell that may hide an ocean of liquid water beneath, making it intriguing for potential life. Ganymede is the largest moon in the solar system, with a mix of ice and rock, and a possible subsurface ocean. Callisto is heavily cratered and icy, with a very old surface. These moons offer diverse and dynamic worlds within our solar system.