AlbaNova Colloquium

Magnetic dynamos: the Earth, the Sun, and laboratory models of the Earth's magnetic field

by Daniel Lathrop (University of Maryland)


During the last solar maximum around 2014, we saw a host of x-class flares and coronal mass ejections from the sun. We experienced few problems this time on Earth due in part to the Earth's magnetic field, which shields us from much of the Sun's charged particle radiation. Surprisingly, that field has weakened throughout recorded history. The origin and dynamics of the magnetic fields of the Earth, Sun, gas giants, and nearly every massive astrophysical object raise numerous questions not completely resolved by existing theoretical, computational and experimental work. The next maximum of solar activity should be around 2024-2025. In this talk I'll review the basics of the Earth's magnetic field, its reversals, recent changes to the magnetic field, and an overview of the solar cycle. Then we will discuss how laboratory experiments can help to understand the processes. By using liquid sodium models of the Earth's core, different international groups seek to better understand what determines the Earth's magnetic field strength, pattern and dynamics by probing the effects of turbulence, Lorentz forces and rotation on core dynamics. While it is not possible to match every aspect of core dynamics in the lab, the experiments seek a comparable force balance among rotation, magnetic fields and advection.