The striped pattern on the parachute used by the Perseverance rover to land on Mars contained a hidden message. Internet sleuths were able to figure it out within a few hours.
Until recently, magnetic fields in the outskirts of galaxies were too faint to be detected. Although it’s still not clear what causes them or how they’re maintained, astronomers have started to create images of their observations of galaxies’ magnetic fields producing beautiful aurora-like effects. See them here.