Glossary:Cosmic Radiation

{{Marvel Database:Glossary Template Cosmic Radiation, also known as cosmic rays or cosmic particles, were initially believed to originate in radioactive isotopes found in the ground. This theory was disproven in 1912 by Victor Hess, who in 1936 received the Nobel prize in physics for his work. Hess used electroscope measurements taken at different altitudes from a hot air balloon to conclude that the radiation was cosmic in origin. Hess further showed that the sun could not be the primary source of cosmic rays by taking balloon measurements during a 1912 solar eclipse.
 * Title            = Cosmic Radiation
 * Image            = Cosmic Rays.jpg
 * Definition       = ==History==

Particle physicists thought that they had discovered Yukawa's theoretical pion in cosmic rays in the late 1930s, but quickly learned that the particle they had found had the right mass but very wrong characteristics. They had actually discovered the muon, the cosmic ray secondary particle that is most copious at the surface of the Earth. Pions interact strongly with nuclei and because of this they very rarely make it to the surface of the Earth. Pions were eventually discovered in mountaintop cosmic ray experiments in 1947.

In 1938, Pierre Auger observed near-simultaneous cosmic ray events at widely separated locations. He concluded that they were due to incident particles whose energy was too high to penetrate the atmosphere. Such particles instead collide with nuclei in the atmosphere, initiating a particle cascade known as a cosmic ray air shower. The events Auger had observed were found to have energies ten million times higher than had previously been known.

Characteristics
Cosmic rays are extremely energetic particles, primarily protons, which originate in the sun, other stars and some of the violent cataclisms which occur in the far reaches of space. The cosmic ray particles interact with the upper atmosphere of the earth and produce showers of lower energy particles. Many of these lower energy particles are absorbed by the earths' atmosphere as they travel down to the surface. At sea level the cosmic radiation is composed mainly of muons, with some gamma-rays , neutrons  and electrons.