"Jupiter is made up predominantly of hydrogen, with some helium. Small traces of other gases also contribute to the planet's composition. These gases fill the entire planet, descending all the way to the core. The surface, as identified by scientists, is the region where the pressure is equal to that at the surface of Earth, one bar. But don't be misled by the term; you can't stand on Jupiter's surface, because it isn't solid. Below the surface, the gas becomes liquid and even plasma, all the way to the central core." https://www.space.com/18391-jupiter-temperature.html