Planetary magnetism

Abstract

Magnetic fields are ubiquitous in the Universe because of the absence (or rarity) of free magnetic monopoles. However, the large scale concentration of magnetic flux in an essentially non‐ferromagnetic body such as the Earth, requires a non‐cosmogonical explanation. A regenerative process must exist because the magnetic diffusion time in the Earth is much less than the age of the Earth. The most popular explanation is the dynamo model in which convectional or precessional fluid motions in the core induce and sustain a magnetic field. Other mechanism are possible in which, for example, thermoelectric effects are important. The advent of planetary probes has led to a dramatic increase in information on the magnetic fields of the five innermost planets. In particular, the recent flybys of Jupiter (by Pioneer 10) and Mercury (by Mariner 10) have yielded unexpected results. These observations are discussed and shown to be reconcilable with present theories of planetary magnetism and solar system chemistry. Some predictions are made for Saturn, Uranus and Neptune.

Files

Additional details