In 1610, an Italian scientist Galileo Galilei looked at Jupiter through a small telescope. Near the planet he saw four dimmer objects. Night after night the objects moved back and forth from one side of Jupiter to the other. These objects turned out to be moons, or natural satellites, of Jupiter. They circle Jupiter the way our Moon circles Earth. Jupiter is named for the king of the gods in ancient Roman myths. The god Jupiter was the ruler of the skies to the early Romans. It is the largest planet in our solar system. Jupiter is an enormous world that makes our own Earth look small. In fact, almost everything about the planet is extreme, its atmosphere, its storms, its temperatures, and its collection of moons, where you can find fiery volcanoes, icy plains, and maybe even salty oceans. Scientists have learned much about Jupiter and its moons...