Jupiter is a gas giant that is the fifth planet from the Sun and the largest planet in the solar system.
The planet is often called the Jovian system and has many moons. Of the planet's moons, four are notable: these are Io, Europa, Ganymede, and Callisto. These moons are often referred to as the Galilean moons because they were first observed by Galileo Galilei using his primitive telescope. The moons themselves are of note because of the possibility for liquid water on the moon of Europa and the massive amount of volcanic activity on the moon of Io.
The planet has a major feature, a massive ongoing storm known as the Great Red Spot that is a massive hurricane-like storm so large that it is readily visible from Earth-based telescopes.
Jupiter in Science Fiction
Jupiter has played a prominent role in science fiction, largely because authors imagine that some of its larger moons would make suitable colonies for an expanding human population.