:::
What are cosmic rays
Cosmic rays are generally believed to originate from supernovae, the Sun, and other galactic activities. Their composition consists of approximately 90% protons, 9% alpha particles (helium nuclei), and about 1% of other heavier atomic nuclei, collectively known as primary cosmic rays. These particles are ejected in all directions at nearly the speed of light, and like all other celestial bodies in the universe, Earth is constantly bombarded by them from all directions. When these cosmic rays enter the atmosphere and interact with gas molecules, they generate a cascade of secondary particles, known as secondary cosmic rays, which are one of the sources of background radiation on the Earth's surface.
更新時間：2025-03-04 14:49