The largest planet in the solar system is Jupiter. It is a gas giant known for its immense size, with a diameter of about 86,881 miles (139,822 kilometers), making it over 11 times wider than Earth. Jupiter is primarily composed of hydrogen and helium and possesses a thick atmosphere featuring striking bands of clouds and famous storms, including the Great Red Spot, a giant storm larger than Earth that has been raging for centuries. Additionally, Jupiter has a powerful magnetic field and dozens of moons, including the four largest known as the Galilean moons: Io, Europa, Ganymede, and Callisto.