Homogeneous dynamos in planetary cores and in the laboratory

New developments have occurred in recent years in the field of dynamo theory. The increase in computer capacity has permitted simulations of convection-driven dynamos in rotating spherical fluid shells in parameter ranges much closer to those of the Earth's core than has been possible before. The progress in handling flows of liquid sodium in large containers, on the other hand, has opened opportunities for realizations of homogeneous dynamos in the laboratory. These developments will lead to a deeper understanding of the origin of magnetic fields in planets and in stars.