Reason for Earth's magnetic field flip?

摘要

Lopsided growth of the Earth's core could explain why its magnetic field reverses direction every few thousand years. If it happened now, we would be exposed to solar winds capable of knocking out global communications and power grids. One side of Earth's solid inner core grows slightly while the other half melts. Peter Olson and Renaud Deguen of Johns Hopkins University used numerical modelling to establish that the axis of Earth's magnetic field lies in the growing hemisphere - a finding that suggests shifts in the field are connected to growth of the inner core (Nature Geoscience, DOI: 10.l038geoi5o6).