Ulkoissäteily

Ulkoissäteily, often translated as external radiation or extraterrestrial radiation, refers to ionizing radiation originating from sources outside Earth's atmosphere. This type of radiation primarily consists of cosmic rays. Cosmic rays are high-energy particles, predominantly protons and atomic nuclei, that travel through space at nearly the speed of light. They are thought to be generated by energetic astrophysical phenomena such as supernovae, active galactic nuclei, and pulsars.

When these cosmic rays encounter Earth's atmosphere, they interact with atmospheric molecules, creating a cascade of secondary particles. These secondary particles, including muons, neutrinos, and gamma rays, also contribute to the overall external radiation dose received on Earth's surface. The intensity of ulkoissäteily varies depending on altitude, latitude, and solar activity. At higher altitudes, such as those experienced by astronauts in space or passengers on high-flying aircraft, exposure to ulkoissäteily is significantly greater due to less atmospheric shielding. Geomagnetic activity, particularly solar flares, can also temporarily increase the flux of these cosmic particles reaching Earth. Understanding ulkoissäteily is crucial for fields like space exploration, aviation safety, and radiation protection.