A magnetosphere is the region of space surrounding an astronomical object in which charged particles are controlled by that object's magnetic field. The magnetic field near the surface of many astronomical objects resembles that of a dipole. The field lines farther away from the surface can be significantly distorted by the flow of electrically conducting plasma emitted from a nearby star (e.g. the solar wind from the Sun).
Planets with a magnetosphere, like Earth, are capable of mitigating or blocking the effects of cosmic radiation....LESS