According to laboratory experiments, the hydrogen and helium that make up the majority of the gas giant’s atmosphere do not mix at the pressures and temperatures found within it. This suggests that hydrogen and helium separate deep within Jupiter’s atmosphere, with the helium forming denser droplets than the hydrogen and causing them to rain down.
The marbled surface of Jupiter is well-known, but what happens far below the cloud tops remains a mystery. As a result, scientists devised an experiment to compress hydrogen and helium to pressures nearly 2 million times that of Earth’s atmosphere and temperatures in the thousands of degrees Celsius, similar to the inner layers of gas giants.
This experiment, in order to figure out whether or not helium rains can be found on Jupiter. This experiment is being led by physicist Marius Millot of the Lawrence Livermore National Laboratory in California and his colleagues. They compressed a mixture of hydrogen and helium between two diamonds in the experiment, then hit it with a powerful laser to compress it even more. The researchers also noticed an abrupt increase in how reflective the material was as the pressure and temperature increased. This indicates that helium was separating from hydrogen, which under these conditions becomes a liquid metal. The reflectivity decreased at even higher pressures and temperatures, indicating that hydrogen and helium had recombined.
According to the researchers, hydrogen and helium would separate about 11,000 kilometers below Jupiter’s cloud tops, down to a depth of about 22,000 kilometers.