Gigantic Planets Holding Billions of Tonnes of Diamonds

The finding comes from a lab experiment at Ohio State University, where scientists recreated the temperatures and pressures of earth’s lower mantle to study how diamonds form there.

The goal was to understand what happens to carbon inside planets in other solar systems, and whether solar systems that are rich in carbon could produce planets that are mostly made of diamond.

Wendy Panero, researcher in the School of Earth Sciences at Ohio State along withdoctoral student Cayman Unterborn used what they learned from the experiments to construct computer models of the minerals that form in planets composed with more carbon than earth.

"It is possible for planets that are as big as 15 times the mass of the Earth to be half made of diamond," said Unterborn, according to a university statement.

"Our results are striking, in that they suggest carbon-rich planets can form with a core and a mantle, just as Earth did," said Panero.

"However, the cores would likely be very carbon-rich much like steel and the mantle would also be dominated by carbon, much in the form of diamond," he added.

Diamonds transfer heat so readily that a carbon super-earth’s interior would quickly freeze. That means no geothermal energy, no plate tectonics, and ultimately no magnetic field or atmosphere.

These findings were presented Tuesday at the American Geophysical Union meeting, San Francisco.