So you thought your fridge magnet was pretty neat. You obviously haven't met the most powerful magnet known to man. Their density and rapid rotation (several times per second) enormously increases the power of their magnetism. If you placed a magnetar where the Moon is, 400,000 kilometres away, it could still wipe your credit cards and rip spoons out of your pockets. A magnetar is a type of neutron star with an incredibly strong magnetic field (a million billion times stronger than that of the Earth), which is formed when certain stars undergo supernova explosions.