\[ **BT: [[Earth#Earth’s properties, structures, and composition]]** ] --- # Earth’s magnetic field Normally, the Earth’s magnetic core generates a magnetic field that protects our planet from harmful radiation from the cosmos and Sun.[^1] ## variations in the main magnetic field e.g. polarity reversals, magnetic storms, magnetospheric substorms, and magnetic pulsations ### geomagnetic excursion A geomagnetic excursion is a significant change in the Earth’s magnetic field.[^2] - see also: [[#Laschamps excursion]] [^1]: Jeff Silberry, dir., *[[Silberry, Megafauna, 2024|Megafauna: What Killed Australia's Giants?]]*, Season 1, Episode 1; accessed 12 February 2025 on ABC iView, <https://iview.abc.net.au/show/megafauna-what-killed-australia-s-giants>. [^2]: ’Geomagnetic excursion’, Wikipedia, last edited 31 October 2025, 23:52 (UTC), <https://en.wikipedia.org/wiki/Geomagnetic_excursion>.