The largest planet in the solar system is Jupiter. It is a gas giant with a diameter of approximately 86,881 miles, which is more than 11 times the diameter of Earth. Jupiter also has more than twice the mass of all the other planets in the solar system combined. Its famous Great Red Spot is a huge storm system that has been raging for at least 350 years and is larger than the size of Earth. Jupiter has many moons, with the four largest being called Io, Europa, Ganymede, and Callisto.