So many dynamoS: The Generation of Magnetic Fields in Planets and Stars

The generation of magnetic field in Earth's interior and the origin of the eleven year solar cycle are both thought to lie in dynamo action of an electrically conducting fluid. In both cases fluid motions interact with rotation to sustain electrical currents and hence magnetic field. In this talk I will give an introduction to some interesting problems for a fluid dynamicist in trying to explain the generation of magnetic field and I will highlight some differences between the geo- and solar dynamo problems. I'll conclude by drawing an analogy of the geodynamo problem with transition to turbulence in flow down a pipe.