Georg von Neumayer’s legacy in geomagnetism

Abstract

Terrestrial magnetism—its temporal and spatial manifestations and origins—has fascinated humans for 2000 years and has long been exploited for navigation. But not until the 19th and early 20th century was systematic mapping and observation of the field undertaken on a global scale, a satisfactory mathematical theory of magnetism developed, and a dynamo origin in the core identified. Georg von Neumayer was one of the leading luminaries who laid the observational basis for these advances. His principal contributions were in persistent and meticulous observation of earth and space science phenomena, particularly in the southern hemisphere, often carried out under challenging conditions. This talk traces the development to modern times of the areas of geomagnetism where von Neumayer played a pioneering role—establishing a world network of magnetic observatories, mapping and modelling of the geomagnetic field, the quest for the origin of the field, exploration geophysics (diagnostic use of magnetic fields to characterise subsurface bodies and geology), solar-terrestrial effects and auroral physics, magnetic disturbances and a relationship with weather, polar science and more. Perhaps his greatest legacy is in the foundation of a spirit of peaceful scientific collaboration between nations and sharing information for the common good. This is best exemplified by his lead role in the first International Polar Year (1882–1883) and its sequel today—the 4th IPY 2007–2008.