He imagines the planets might have powerful protective magnetic fields, and creatures on the surface would lumber around in thick, radiation - resistant armor. (discovermagazine.com)
And without a protective magnetic field around the planet, solar radiation would have stripped Earth's atmosphere and bombarded the surface, which was apparently the fate of Mars. (discovermagazine.com)
Such cycling, and the protective magnetic field generated by the core, keep our planet at the perfect temperature for life. (discovermagazine.com)