Observations: AstronomyCast Cosmic Rays

Cosmic rays are energetic charged subatomic particles, originating in outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. Most primary cosmic rays (those that enter the atmosphere from deep space) are composed of familiar stable subatomic particles that normally occur on Earth, such as protons, atomic nuclei, or electrons. Although most of the subatomic particles are stable protons and neutrons, a small fraction that enter the Earth's atmosphere occur as stable particles of antimatter. Antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles. For example, a positron and an antiproton can form an antihydrogen atom in the same way that an electron and a proton form a "normal matter" hydrogen atom. Furthermore, mixing matter and antimatter can lead to the annihilation of both. The flux of incoming cosmic rays at the upper atmosphere is dependent on the solar wind, the Earth's magnetic field, and the energy of the cosmic rays.