Final answer:
Galactic cosmic rays, originating from supernova explosions and trapped by the Milky Way's magnetic field, can cause illnesses by damaging biological tissues and genetic material, leading to mutations and various health issues.
Step-by-step explanation:
Galactic cosmic rays can cause different types of illnesses in humans because they are high-energy particles that originate from outside the Earth's atmosphere, including from supernova explosions within the Milky Way. These particles, which include protons, helium nuclei, and heavier nuclei, can cause ionization in biological tissues, potentially leading to cellular damage, genetic mutations, and various health issues. Supernovae, the violent deaths of stars, produce shock waves that accelerate charged particles to near-light speeds, ultimately becoming cosmic rays that can influence genetic material and contribute to mutations over billions of years. Cosmic rays are also important in the galactic enrichment process and the evolution of life. However, long-term exposure to radiation, including cosmic rays, from various sources such as medical tests, radon from the ground, and increased exposure during airplane flights, can increase the risk of illnesses due to their potential to damage living tissues.