Radiation sometimes comes up the news in the context of the risks associated with long-distance space travel. It turns out that dying stars and all the other strange stuff in space generates a lot of exotic and strange types of radiation—even beyond the types described above. These unusual, high-energy particles are collectively called cosmic radiation, and in many parts of space they mostly consist of extremely high energy photons, or gamma radiation. Recall that gamma radiation is particularly dangerous because photons can pass through most barriers and thus travel deep into living tissues, where they can cause internal damage (and eventually cancer).
In a spaceship, astronauts don’t have the full benefit of Earth’s thick atmosphere to protect them from cosmic rays. This means that any long-term space travel initiative (such as a mission to mars) will have to invest considerable resources in properly shielding the living areas of the spaceship with materials that are impervious to cosmic radiation. The development of materials that can shield astronauts is an active area of research!