Is the Earth’s Magnetic Field a Constant? A Legacy of Poisson

In the report he submitted to Académie des Sciences, Poisson imagined a set of concentric spheres at origin Earth’s magnetic field. It may come as surprise many that well Gauss both considered field be constant. We propose in this study test surprising assertion for first time, evoked by 1826. First, we present development Maxwell’s equations framework static electric and order draw necessary consequences hypothesis. second step, see if observations can agreement with Poisson. To do so, choose compare (1) polar motion drift secular variation field, (2) seasonal pseudo-cycles day length together those sea level recorded different tide gauges around globe observatories. then mechanism, spirit Poisson, explain presence 11-year cycle mechanism observations, finally, closely evolution g1,0 coefficient International Geomagnetic Reference Field (IGRF) over time.