Global magnetic fields are generated by the sun, some terrestrial planets and all our giant gaseous planets. The sun’s magnetic poles reversed in 2001, and will do so again in 2012 in relation to the 11-year sunspot cycle. On Earth, magnetic poles reverse every 250,000 years on average. Our last reversal occurred 720,000 years ago, and there are reasons to believe the next one is imminent (in geologic terms).
In planets and stars, magnetic fields are produced by internal dynamos. These dynamos require motion, similar to simple electric generators which use rotating coils of wire and magnetic fields. In the Earth, it’s the sea of molten iron which circulates the inner core that comprises the dynamo. In stars and gaseous planets like Jupiter, the motion occurs within an electrically conducting fluid.
As supercomputers continue to improve, so do computer simulations used to study fluid flows and magnetic fields in planets and stars. Some simulations attempt to explain what is well observed (ex. why do our poles reverse?); others predict what has not yet been measured (ex. what is at Jupiter’s core?).
Physicist Gary Glatzmaier is a pioneer in the development of computer models used to study magnetohydrodynamics. Join him for a discussion probing the internal physics of planets and stars. He will present several examples of simulations used to study the dynamics in the interiors of the terrestrial planets, giant planets like Jupiter and stars. He will also show animations which illustrate the spatial patterns and time dependencies of the computer simulated flows and fields.
- A simulated dipole reversal on Earth, courtesy of Glatzmaier’s geodynamo model and PBS Nova: See a Reversal
- An article by Glatzmaier in Scientific American: Probing the Geodynamo
- Video showing work at the University of Maryland to build a physical model of the Earth’s geodynamo: Three Meter Experiment
- Do you want to build your own magnetic field viewer? Buy some steel wool and a bottle of baby oil, then watch this: Magnetic field viewer
Glatzmaier received his PhD in physics from the University of Colorado (Boulder). He studied solar physics as a post-doc, and then spent 14 years at Los Alamos National Laboratory focusing on geophysics. He is currently a professor of Earth and Planetary Sciences at UC Santa Cruz.