Date Time Lab team uses giant lasers to compress iron oxide, revealing secret interior of rocky exoplanets An artistic rendering of the interior structure of Earth (left) compared to a large rocky exoplanet (right). Credit: John Jett and Federica Coppari/LLNL. Advances in astronomical observations have resulted in the discovery of an extraordinary number of extrasolar planets, some of which are believed to have a rocky composition similar to Earth. Learning more about their interior structure could provide important clues about their potential habitability. Led by Lawrence Livermore National Laboratory (LLNL), a team of researchers aims to unlock some of these secrets by understanding the properties of iron oxide – one of the constituents of Earth’s mantle – at the extreme pressures and temperatures that are likely found in the interiors of these large rocky extrasolar planets. The results of their experiments were published today in Nature Geoscience.