A sheet-metal geodynamo

摘要

A decade of modelling Earth's core on computers has led to the belief that we understand what produces Earth's magnetic field. More realistic simulations are now shaking that complacency. Earth's magnetic field is often depicted as though a gigantic bar magnet resides inside our planet. In fact, the magnetic field is created by strong electrical currents generated by a dynamo process resulting from the flow of molten iron in Earths outer core. An important feature of this motion is thought to be spiralling flows in the form of long columns running parallel to Earth's axis.