Washington, August 7 : A new study has suggested that giant, gaseous planets such as Jupiter and Saturn are filled with a liquid metal alloy of helium and hydrogen.
The study was carried out by researchers from the University of California, Berkeley, and in London.
It demonstrates that metallic helium is less rare than was previously thought and is produced under the kinds of conditions present at the centers of giant, gaseous planets, mixing with metal hydrogen and forming a liquid metal alloy.
"This is a breakthrough in terms of our understanding of materials, and that's important because in order to understand the long-term evolution of planets, we need to know more about their properties deep down," said Raymond Jeanloz, professor of astronomy and of earth and planetary science at UC Berkeley and one of the authors of the study.
"The finding is also interesting from the point of view of understanding why materials are the way they are, and what determines their stability and their physical and chemical properties," he added.
Pressures at Jupiter's core, for example, reach 70 million times Earth's atmospheric pressure, the planet's massive size more than offsetting its low density.
The cores of Jupiter and Saturn are a balmy 10,000 to 20,000 degrees Celsius, two to four times hotter than the surface of the sun.
In this study, Jeanloz and Lars Stixrude, earth sciences professor at University College London, took a closer look at what happens to helium under such extreme conditions.
They used theories based on quantum mechanics to calculate the behavior of helium under different pressures and temperatures.
According to Stixrude, although these equations are only approximations, the researchers' predictions closely matched experimental results for lower pressures.
Under Earthly conditions, helium is a colorless, see-through, electrically insulating gas.
But under the kinds of pressure and temperature found at the centers of Jupiter and Saturn, the researchers found that helium turns into a liquid metal, like mercury.
"You can imagine this liquid looking like mercury, only less reflective," said Jeanloz. "The finding was a surprise, as scientists had assumed that high pressures and high temperatures would make metallization of elements such as helium more difficult, not easier," he added.
Scientists recently discovered that hydrogen metalizes under lower temperatures and pressures than was previously appreciated.
But, the dogma in the field was that the characteristics of hydrogen and helium were different enough that the two wouldn't mix inside giant gaseous planets.
The researchers' findings, however, indicate that the two elements probably do mix, forming a metal alloy like brass, but liquid.