Jupiter is the largest planet in our solar system, with a diameter of about 86,881 miles (139,822 kilometers). It is a gas giant, primarily composed of hydrogen and helium, and has a very strong magnetic field. Jupiter has a Great Red Spot, which is a massive storm that has been raging for hundreds of years. It also has at least 79 moons, with the four largest being Ganymede, Io, Callisto, and Europa. Jupiter's immense size and mass have a significant impact on the solar system, affecting the orbits of other objects.