6 April, 9pm, BBC Radio 4.
Observations of the Earth's core show worrying signs the magnetic field is due for a reversal. Scientists predict lethal radiation reaching the Earth's surface during a reversal, with disastrous consequences for the atmosphere, climate and life. Peter Evans talks to scientists attempting to create physical models of the core in the laboratory. It is hoped these magnetic dynamos - giant rotating spheres of molten material - will further understanding of core processes and help predict changes in the magnetic field.