Diamonds leave planets out in the cold.

• Position: YOUR LIFE - Brief article

A planet comprised of diamonds may sound lovely, but you would not want to live there. A study presented at the annual American Geophysical Union suggests that some stars in the Milky Way could harbor "carbon super-Earths"--giant terrestrial planets that contain up to 50% diamond.

"To date, more than 500 planets have been discovered outside of our solar system, yet we know very little about their internal compositions," points out study coauthor Cayman Unterborn.

"It's possible for planets that are 15 times the mass of Earth to be half made of diamond. Our results suggest carbon-rich planets can form with a core and mantle, just as Earth did. 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."

Earth's core is mostly iron, and the mantle predominantly silica-based minerals, a result...