<p> The Jupiter System - Highlights</p><p> Jupiter is the largest and most massive planet in the solar system, 318 Earth masses, 2.5 times the mass of all other planets combined, 1400 times Earth's volume.  Jupiter is a gas giant planet; composed largely of hydrogen and helium. Due to its strong gravity and cold temperatures, Jupiter has held on to its light gases, unlike the smaller, warmer terrestrial worlds.  The planet rotates in 9 hrs, 55 mins, the fastest of any planet, causing a noticeable equatorial bulge. The diameter through the poles is 9200 kilometers smaller than the diameter through the equator.  Visual observations from Earth show the top of a banded, gaseous atmosphere -- there is NO solid surface underneath.  The atmosphere appears banded, divided into bright zones and darker belts, which are caused by convection and the planet’s strong rotation. Occasional storms are visible as distinct rotating "spots" within the general atmospheric circulation.  Jupiter emits twice as much energy as it receives from the Sun – the excess energy is leftover heat from Jupiter’s formation. This heat from the interior helps drive the dynamic jovian atmosphere.  The interior of Jupiter is a region of intense pressures and high temperatures. Hydrogen, the dominant constituent is compressed into a metallic state, an excellent conductor of electricity.  At its center, Jupiter likely possesses a rocky-metallic core 10-20 times the mass of Earth.  The jovian magnetosphere, generated by the fast-rotating metallic hydrogen interior, is an intense source of centimeter-band (radio) radiation, and is substantially more powerful than Earth's magnetic field.  The jovian system, like all of the gas giants, is a miniature solar system, containing many moons and a ring system.  Jupiter has 28 known moons, including the four large moons discovered by Galileo: Io, Europa, Ganymede and Callisto, each a strange and fascinating world of its own.  Jupiter’s thin ring, discovered by the Voyager spacecraft, is not visible from Earth  Jupiter’s gravity strongly affects the orbits of passing comets and asteroids. In 1994, a comet crashed into Jupiter, a unique cosmic event. The gas giants, especially Jupiter, are still evolving.</p>