Melvyn Bragg and his guests discuss the Earth’s Core. The inner core is an extremely dense, solid ball of iron and nickel, the size of the Moon, while the outer core is a flowing liquid, the size of Mars. Thanks to the magnetic fields produced within the core, life on Earth is possible. The magnetosphere protects the Earth from much of the Sun’s radiation and the flow of particles which would otherwise strip away the atmosphere. The precise structure of the core and its properties have been fascinating scientists from the Renaissance. Recent seismographs show the picture is even more complex than we might have imagined, with suggestions that the core is spinning at a different speed and on a different axis from the surface. With Stephen Blundell Professor of Physics and Fellow of Mansfield College at the University of Oxford Arwen Deuss Associate Professor in Seismology at Utrecht University and Simon Redfern Professor of Mineral Physics at the University of Cambridge Producer: Simon Tillotson.