Jupiter’s rocky centre is dissolving gradually, new calculations have suggested. The new work may help clarify why the core of the planet appears smaller and why its atmosphere richer in heavy elements than has been previously predicted.
Massive planets like Jupiter and Saturn are thought to have evolved as solid bodies of rock and ice. When they grew to about 10 times the mass of the Earth, their gravity pulled in gas from their birth nebula, giving them thick atmosphere that comprises mainly of hydrogen.
However, some studies have suggested that Jupiter’s heart may weigh less than 10 Earths, while the core of Saturn may weigh similar to 15 to 30 Earths.
Researchers led by Shu Lin Li of Peking University in China offered a grisly explanation last year, stating that a rocky planet bigger than Earth slammed into Jupiter long ago, vaporising most of the planet’s core.
Now, Hugh Wilson and Burkhard Militzer from the University of California, Berkeley, have suggested a competing explanation, stating that Jupiter’s core has gradually been dissolving since its formation almost 4.5 billion years ago.
According to other researchers, Jupiter’s core may dissolve into the surrounding atmosphere due to the intense pressure and temperature at its heart.
“We sat down to figure out, does this actually happen?” New Scientist quoted Wilson as saying.
The researchers used the equations of quantum mechanics to see how magnesium oxide, the mineral thought to be a constituent of the planet’s core, behaves at Jupiter-like pressures of about 40 million Earth atmospheres and temperatures of 20,000 degrees.
They found that the mineral dissolves into its fluid surroundings in those conditions.
“You can think of it as if you have some salt in the bottom of a glass. Pour warm water on the salt and it will start to dissolve in the glass, with salty water in the bottom and less salty water at the top,” Wilson said.
Wilson believes that the dissolved rock may get mixed into the rest of the atmosphere over time.
“It could at least partially explain both the enrichment of heavy elements in the outer atmosphere and also the fact that its core may be smaller than formation models would suggest,” he added.