One of the many unseen forces to which you owe your existence is magnetism. If it weren’t for the magnetic field that surrounds our planet, blocking cosmic radiation and solar wind, Earth would likely have little atmosphere to speak of. Life (at least of the human variety) would be impossible.
Changes in the field can also play havoc with satellite communication and electric infrastructure, disrupting the modern world in a big way. Given the importance of this gargantuan bar magnet in our day-to-day lives, it’s worth understanding how it works — and when it doesn’t.
Since the magnetic field is sustained by geological activity deep within our planet, let’s start with an overview of its structure.
Although we’ve hardly scratched Earth’s surface (the center lies nearly 4,000 miles deep, and the deepest borehole penetrated just 7.6 miles), scientists can study the interior with some help from earthquakes: As seismic waves ...
