Much of Jupiter’s core contains metallic hydrogen.
Metallic hydrogen is a species of supercompressed hydrogen found in the cores of gas giants and stars. As hydrogen heads the alkali metal column of the Periodic Table, it has been known for some time that it has the potential to be a metal, but only under extreme pressures. Metallic hydrogen is crushed so tightly that atomic nuclei are separated only by a dense soup of electrons flowing between them. It is significantly less dense than neutronium, however, where electrons fuse with protons in hydrogen to form neutrons. Like all metals, it is conductive and requires an electrical current to measure the presence of metallization.
The metallic form of hydrogen is found in gas giants and stars.
This material was only synthesized under laboratory conditions in 1996 at Lawrence Livermore National Laboratory. It only existed for about a microsecond and required temperatures of thousands of degrees and pressure of over a million atmospheres to achieve. This came as a surprise, as it was previously thought that solid (very cold) hydrogen was needed to produce metallic hydrogen. Previous experiments have subjected solid hydrogen to pressures of up to 2.5 million atmospheres in the absence of any detectable metallization, so the experiment involving the compression of hot hydrogen was set up to measure other properties of the material, not with the intention of producing metallic hydrogen. . However, that’s how it was first done.
Metallic hydrogen was only synthesized under laboratory conditions in 1996 at the Lawrence Livermore National Laboratory.
Although the metallic hydrogen produced at Lawrence Livermore National Laboratory was solid, it has been theorized that it may be possible to create a liquid version if even higher pressures, around 4 million atmospheres, are used. Calculations have also determined that this material can be a superconductor at room temperature, although this property is somewhat useless for practical purposes, as the cost of compressing something to over a million atmospheres over a long period of time is much higher than to cool something down to near absolute zero. However, there is a small chance that metastable metallic hydrogen is possible – that is, one that retains its phase even when pressure is removed.
Metallic hydrogen is thought to exist in the cores of the largest gas giants in our solar system: Jupiter and Saturn, as well as a layer of hydrogen near the Sun’s core.