Jupiter-like Planets and "Super-Jupiter"
These are gas planets in the classical sense, whose mass and composition resemble those of Jupiter, the largest and most massive planet in our solar system. There are also many objects with the multiple Jupiter mass. They are thought to consist mainly of hydrogen and helium as well as methane. Their formation is suspected to have occurred in the colder areas of their solar system. These planets have no solid surface. Rather, the gases of their atmosphere change to a supercritical state with increasing pressure, at which the phase boundary between gas and liquid disappears. In the lower layers the presence of metallic hydrogen is suspected, and possibly a rocky or metallic core.