Anytime astronomers figure out a new way of looking for magnetic fields in ever more remote regions of the cosmos, inexplicably, they find them.
These force fields—the same entities that emanate from fridge magnets—surround Earth, the sun, and all galaxies. Twenty years ago, astronomers started to detect magnetism permeating entire galaxy clusters, including the space between one galaxy and the next. Invisible field lines swoop through intergalactic space like the grooves of a fingerprint.
Last year, astronomers finally managed to examine a far sparser region of space—the expanse between galaxy clusters. There, they discovered the largest magnetic field yet: 10 million light-years of magnetized space spanning the entire length of