Magnetosphere

The Magnetosphere is the region of space surrounding a celestial object that is affected by the objects magnetic field.

Origin

The Earth's magnetosphere is thought to be generated by its rotating iron core.

Effect

A magnetoshere of sufficient stregnth will serve to protect the occupants of a planet from the harmful radiation of their star and the surrounding cosmos. The results of this protection can be seen as aurorae in the far northern and southern latitudes.

Because Mars lacks a significant magnetic field, it's magnetosphere offers neglegable protection from radiation