Jupiter

The most massive planet in our solar system, with four large moons and many smaller moons. Jupiter forms a kind of miniature solar system. Jupiter resembles a star in composition. In fact, if It had been about 80 times more massive, it would have become a star rather than a planet.

The composition of Jupiter's atmosphere is similar to that of the Sun—mostly hydrogen and helium. Deep in the atmosphere, the pressure and temperature increase, compressing the hydrogen gas into a liquid. At depths about a third of the way down, the hydrogen becomes metallic and electrically conducting. In this metallic layer, Jupiter's powerful magnetic field is generated by electrical currents driven by Jupiter's fast ration. At the center, the immense pressure may support a solid core of rock about the size of Earth.